In
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
, imperative programming is a
programming paradigm of
software
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work.
At the lowest programming level, executable code consist ...
that uses
statements that change a program's
state. In much the same way that the
imperative mood
The imperative mood is a grammatical mood that forms a command or request.
The imperative mood is used to demand or require that an action be performed. It is usually found only in the present tense, second person. To form the imperative mood, ...
in
natural languages expresses commands, an imperative program consists of
command
Command may refer to:
Computing
* Command (computing), a statement in a computer language
* COMMAND.COM, the default operating system shell and command-line interpreter for DOS
* Command key, a modifier key on Apple Macintosh computer keyboards
* ...
s for the
computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...
to perform. Imperative programming focuses on describing ''how'' a program operates step by step, rather than on high-level descriptions of its expected results.
The term is often used in contrast to
declarative programming, which focuses on ''what'' the program should accomplish without specifying all the details of ''how'' the program should achieve the result.
Imperative and procedural programming
Procedural programming is a type of imperative programming in which the program is built from one or more procedures (also termed
subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed.
Functions may ...
s or functions). The terms are often used as synonyms, but the use of procedures has a dramatic effect on how imperative programs appear and how they are constructed. Heavy procedural programming, in which
state changes are localized to procedures or restricted to explicit arguments and returns from procedures, is a form of
structured programming. From the 1960s onwards, structured programming and
modular programming in general have been promoted as techniques to improve the
maintainability and overall quality of imperative programs. The concepts behind
object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
attempt to extend this approach.
Procedural programming could be considered a step toward declarative programming. A programmer can often tell, simply by looking at the names, arguments, and return types of procedures (and related comments), what a particular procedure is supposed to do, without necessarily looking at the details of how it achieves its result. At the same time, a complete program is still imperative since it ''fixes'' the statements to be executed and their order of execution to a large extent.
Rationale and foundations of imperative programming
The programming paradigm used to build programs for almost all computers typically follows an imperative model.
[ Reconfigurable computing is a notable exception.] Digital computer hardware is designed to execute
machine code, which is native to the computer and is usually written in the imperative style, although low-level compilers and interpreters using other paradigms exist for some architectures such as
lisp machines.
From this low-level perspective, the program state is defined by the contents of memory, and the statements are instructions in the native machine language of the computer. Higher-level imperative languages use
variables and more complex statements, but still follow the same paradigm.
Recipes and process
checklist
A checklist is a type of job aid used in repetitive tasks to reduce failure by compensating for potential limits of human memory and attention. It helps to ensure consistency and completeness in carrying out a task. A basic example is the " to d ...
s, while not
computer program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. Computer programs are one component of software, which also includes software documentation, documentation and oth ...
s, are also familiar concepts that are similar in style to imperative programming; each step is an instruction, and the physical world holds the state. Since the basic ideas of imperative programming are both conceptually familiar and directly embodied in the hardware, most computer languages are in the imperative style.
Assignment statements, in imperative paradigm, perform an operation on information located in memory and store the results in memory for later use. High-level imperative languages, in addition, permit the
evaluation of complex
expressions, which may consist of a combination of
arithmetic operations and
function evaluations, and the assignment of the resulting value to memory. Looping statements (as in
while loops,
do while loops, and
for loops) allow a sequence of statements to be executed multiple times. Loops can either execute the statements they contain a predefined number of times, or they can execute them repeatedly until some condition is met.
Conditional
Conditional (if then) may refer to:
*Causal conditional, if X then Y, where X is a cause of Y
*Conditional probability, the probability of an event A given that another event B has occurred
*Conditional proof, in logic: a proof that asserts a co ...
branching statements allow a sequence of statements to be executed only if some condition is met. Otherwise, the statements are skipped and the execution sequence continues from the statement following them. Unconditional branching statements allow an execution sequence to be transferred to another part of a program. These include the jump (called ''
goto'' in many languages),
switch, and the subprogram,
subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed.
Functions may ...
, or procedure call (which usually returns to the next statement after the call).
Early in the development of
high-level programming language
In computer science, a high-level programming language is a programming language with strong abstraction from the details of the computer. In contrast to low-level programming languages, it may use natural language ''elements'', be easier to u ...
s, the introduction of the
block enabled the construction of programs in which a group of statements and declarations could be treated as if they were one statement. This, alongside the introduction of
subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed.
Functions may ...
s, enabled complex structures to be expressed by hierarchical decomposition into simpler procedural structures.
Many imperative programming languages (such as
Fortran,
BASIC, and
C) are
abstractions of
assembly language.
History of imperative and object-oriented languages
The earliest imperative languages were the machine languages of the original computers. In these languages, instructions were very simple, which made hardware implementation easier but hindered the creation of complex programs.
FORTRAN, developed by
John Backus at
International Business Machines (IBM) starting in 1954, was the first major programming language to remove the obstacles presented by machine code in the creation of complex programs. FORTRAN was a
compiled language that allowed named variables, complex expressions, subprograms, and many other features now common in imperative languages. The next two decades saw the development of many other major high-level imperative programming languages. In the late 1950s and 1960s,
ALGOL was developed in order to allow mathematical algorithms to be more easily expressed and even served as the
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
's target language for some computers.
MUMPS (1966) carried the imperative paradigm to a logical extreme, by not having any statements at all, relying purely on commands, even to the extent of making the IF and ELSE commands independent of each other, connected only by an intrinsic variable named $TEST.
COBOL (1960) and
BASIC (1964) were both attempts to make programming syntax look more like English. In the 1970s,
Pascal
Pascal, Pascal's or PASCAL may refer to:
People and fictional characters
* Pascal (given name), including a list of people with the name
* Pascal (surname), including a list of people and fictional characters with the name
** Blaise Pascal, Frenc ...
was developed by
Niklaus Wirth, and
C was created by
Dennis Ritchie while he was working at
Bell Laboratories
Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984),
then AT&T Bell Laboratories (1984–1996)
and Bell Labs Innovations (1996–2007),
is an American industrial Research and development, research and scientific developm ...
. Wirth went on to design
Modula-2 and
Oberon. For the needs of the
United States Department of Defense
The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...
,
Jean Ichbiah and a team at
Honeywell
Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
began designing
Ada
Ada may refer to:
Places
Africa
* Ada Foah, a town in Ghana
* Ada (Ghana parliament constituency)
* Ada, Osun, a town in Nigeria
Asia
* Ada, Urmia, a village in West Azerbaijan Province, Iran
* Ada, Karaman, a village in Karaman Province, T ...
in 1978, after a 4-year project to define the requirements for the language. The specification was first published in 1983, with revisions in 1995, 2005, and 2012.
The 1980s saw a rapid growth in interest in
object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
. These languages were imperative in style, but added features to support
objects
Object may refer to:
General meanings
* Object (philosophy), a thing, being, or concept
** Object (abstract), an object which does not exist at any particular time or place
** Physical object, an identifiable collection of matter
* Goal, an ai ...
. The last two decades of the 20th century saw the development of many such languages.
Smalltalk-80, originally conceived by
Alan Kay in 1969, was released in 1980, by the Xerox Palo Alto Research Center (
PARC). Drawing from concepts in another object-oriented language—
Simula (which is considered the world's first
object-oriented programming language, developed in the 1960s)—
Bjarne Stroustrup designed
C++, an object-oriented language based on
C. Design of
C++ began in 1979 and the first implementation was completed in 1983. In the late 1980s and 1990s, the notable imperative languages drawing on object-oriented concepts were
Perl
Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offic ...
, released by
Larry Wall in 1987;
Python, released by
Guido van Rossum in 1990;
Visual Basic and
Visual C++ (which included
Microsoft Foundation Class Library
Microsoft Foundation Class Library (MFC) is a C++ object-oriented library for developing desktop applications for Windows.
MFC was introduced by Microsoft in 1992 and quickly gained widespread use. While Microsoft has introduced alternative ...
(MFC) 2.0), released by
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washi ...
in 1991 and 1993 respectively;
PHP, released by
Rasmus Lerdorf in 1994;
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
, by
James Gosling (
Sun Microsystems
Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, t ...
) in 1995,
JavaScript
JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
, by
Brendan Eich (
Netscape), and
Ruby
A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...
, by Yukihiro "Matz" Matsumoto, both released in 1995. Microsoft's
.NET Framework
The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
(2002) is imperative at its core, as are its main target languages,
VB.NET and
C# that run on it; however Microsoft's
F#, a functional language, also runs on it.
Examples
Fortran
FORTRAN (1958) was unveiled as "The IBM Mathematical FORmula TRANslating system." It was designed for scientific calculations, without
string handling facilities. Along with
declarations,
expressions, and
statements, it supported:
*
arrays
*
subroutine
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed.
Functions may ...
s
*
"do" loops
It succeeded because:
* programming and debugging costs were below computer running costs
* it was supported by IBM
* applications at the time were scientific.
However, non IBM vendors also wrote Fortran compilers, but with a syntax that would likely fail IBM's compiler.
The
American National Standards Institute (ANSI) developed the first Fortran standard in 1966. In 1978, Fortran 77 became the standard until 1991. Fortran 90 supports:
*
records
*
pointers to arrays
COBOL
COBOL (1959) stands for "COmmon Business Oriented Language." Fortran manipulated symbols. It was soon realized that symbols didn't need to be numbers, so strings were introduced.
The
US Department of Defense
The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...
influenced COBOL's development, with
Grace Hopper being a major contributor. The statements were English-like and verbose. The goal was to design a language so managers could read the programs. However, the lack of structured statements hindered this goal.
COBOL's development was tightly controlled, so dialects didn't emerge to require ANSI standards. As a consequence, it wasn't changed for 25 years until 1974. The 1990s version did make consequential changes, like
object-oriented programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
.
Algol
ALGOL (1960) stands for "ALGOrithmic Language." It had a profound influence on programming language design.
Emerging from a committee of European and American programming language experts, it used standard mathematical notation and had a readable structured design. Algol was first to define its
syntax
In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure ( constituenc ...
using the
Backus–Naur form.
This led to
syntax-directed compilers. It added features like:
* block structure, where variables were local to their block
* arrays with variable bounds
*
"for" loops
*
functions
*
recursion
Recursion (adjective: ''recursive'') occurs when a thing is defined in terms of itself or of its type. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in mathematic ...
Algol's direct descendants include
Pascal
Pascal, Pascal's or PASCAL may refer to:
People and fictional characters
* Pascal (given name), including a list of people with the name
* Pascal (surname), including a list of people and fictional characters with the name
** Blaise Pascal, Frenc ...
,
Modula-2,
Ada
Ada may refer to:
Places
Africa
* Ada Foah, a town in Ghana
* Ada (Ghana parliament constituency)
* Ada, Osun, a town in Nigeria
Asia
* Ada, Urmia, a village in West Azerbaijan Province, Iran
* Ada, Karaman, a village in Karaman Province, T ...
,
Delphi and
Oberon on one branch. On another branch there's
C,
C++ and
Java
Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
.
Basic
BASIC (1964) stands for "Beginner's All Purpose Symbolic Instruction Code." It was developed at
Dartmouth College
Dartmouth College (; ) is a private research university in Hanover, New Hampshire. Established in 1769 by Eleazar Wheelock, it is one of the nine colonial colleges chartered before the American Revolution. Although founded to educate Native ...
for all of their students to learn.
If a student didn't go on to a more powerful language, the student would still remember Basic.
A Basic interpreter was installed in the
microcomputers manufactured in the late 1970s. As the microcomputer industry grew, so did the language.
Basic pioneered the
interactive session.
It offered
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
commands within its environment:
* The 'new' command created an empty slate
* Statements evaluated immediately
* Statements could be programmed by preceding them with a line number
* The 'list' command displayed the program
* The 'run' command executed the program
However, the Basic syntax was too simple for large programs.
Recent dialects added structure and object-oriented extensions.
Microsoft's Visual Basic is still widely used and produces a
graphical user interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, ins ...
.
C
C programming language (1973) got its name because the language
BCPL was replaced with
B, and
AT&T Bell Labs called the next version "C." Its purpose was to write the
UNIX
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ...
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
.
C is a relatively small language -- making it easy to write compilers. Its growth mirrored the hardware growth in the 1980s.
Its growth also was because it has the facilities of
assembly language, but uses a
high-level syntax. It added advanced features like:
*
inline assembler
* arithmetic on pointers
* pointers to functions
* bit operations
* freely combining complex
operators
''C'' allows the programmer to control which region of memory data is to be stored. ''Global variables'' and ''static variables'' require the fewest
clock cycles to store. The
stack
Stack may refer to:
Places
* Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group
* Blue Stack Mountains, in Co. Donegal, Ireland
People
* Stack (surname) (including a list of people ...
is automatically used for the standard variable
declarations.
Heap memory is returned to a
pointer variable from the
malloc()
function.
* The ''global and static data'' region is located just above the ''program'' region. (The program region is technically called the ''text'' region. It's where machine instructions are stored.)
:* The global and static data region is technically two regions.
One region is called the ''initialized
data segment'', where variables declared with default values are stored. The other region is called the ''
block started by segment'', where variables declared without default values are stored.
:* Variables stored in the ''global and static data'' region have their
addresses set at compile-time. They retain their values throughout the life of the process.
:* The global and static region stores the ''global variables'' that are declared on top of (outside) the
main()
function.
Global variables are visible to
main()
and every other function in the source code.
: On the other hand, variable declarations inside of
main()
, other functions, or within
block delimiters are ''local variables''. Local variables also include ''
formal parameter
In computer programming, a parameter or a formal argument is a special kind of variable used in a subroutine to refer to one of the pieces of data provided as input to the subroutine. These pieces of data are the values of the arguments (often ...
variables''. Parameter variables are enclosed within the parenthesis of function definitions.
They provide an
interface to the function.
:* ''Local variables'' declared using the
static
prefix are also stored in the ''global and static data'' region.
Unlike global variables, static variables are only visible within the function or block. Static variables always retain their value. An example usage would be the function
int increment_counter()
* The
stack
Stack may refer to:
Places
* Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group
* Blue Stack Mountains, in Co. Donegal, Ireland
People
* Stack (surname) (including a list of people ...
region is a contiguous block of memory located near the top memory address.
Variables placed in the stack, ironically, are populated from top to bottom.
A
stack pointer is a special-purpose
register
Register or registration may refer to:
Arts entertainment, and media Music
* Register (music), the relative "height" or range of a note, melody, part, instrument, etc.
* ''Register'', a 2017 album by Travis Miller
* Registration (organ), th ...
that keeps track of the last memory address populated.
Variables are placed into the stack via the ''assembly language'' PUSH instruction. Therefore, the addresses of these variables are set during
runtime. The method for stack variables to lose their
scope
Scope or scopes may refer to:
People with the surname
* Jamie Scope (born 1986), English footballer
* John T. Scopes (1900–1970), central figure in the Scopes Trial regarding the teaching of evolution
Arts, media, and entertainment
* Cinema ...
is via the POP instruction.
:* ''Local variables'' declared without the
static
prefix, including formal parameter variables,
are called ''automatic variables''
and are stored in the stack.
They are visible inside the function or block and lose their scope upon exiting the function or block.
* The
heap region is located below the stack.
It is populated from the bottom to the top. The
operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs.
Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
manages the heap using a ''heap pointer'' and a list of allocated memory blocks.
Like the stack, the addresses of heap variables are set during runtime. An
out of memory error occurs when the heap pointer and the stack pointer meet.
:* ''C'' provides the
malloc()
library function to
allocate heap memory.
Populating the heap with data is an additional copy function. Variables stored in the heap are economically passed to functions using pointers. Without pointers, the entire block of data would have to be passed to the function via the stack.
C++
In the 1970s,
software engineers
Software engineering is a systematic engineering approach to software development.
A software engineer is a person who applies the principles of software engineering to design, develop, maintain, test, and evaluate computer software. The term ' ...
needed language support to break large projects down into
modules
Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
.
One obvious feature was to decompose large projects ''physically'' into separate
files. A less obvious feature was to decompose large projects ''logically'' into
abstract datatypes.
At the time, languages supported concrete (
scalar) datatypes like
integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign ( −1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the languag ...
numbers,
floating-point numbers, and
strings of
characters. Concrete datatypes have their representation as part of their name.
Abstract datatypes are
structures of concrete datatypes — with a new name assigned. For example, a
list of integers could be called
integer_list
.
In object-oriented jargon, abstract datatypes are called
classes. However, a ''class'' is only a definition; no memory is allocated. When memory is allocated to a class, it's called an
object
Object may refer to:
General meanings
* Object (philosophy), a thing, being, or concept
** Object (abstract), an object which does not exist at any particular time or place
** Physical object, an identifiable collection of matter
* Goal, an ...
.
''
Object-oriented imperative languages'' developed by combining the need for classes and the need for safe
functional programming
In computer science, functional programming is a programming paradigm where programs are constructed by applying and composing functions. It is a declarative programming paradigm in which function definitions are trees of expressions tha ...
.
A function, in an object-oriented language, is assigned to a class. An assigned function is then referred to as a
method,
member function, or ''
operation
Operation or Operations may refer to:
Arts, entertainment and media
* ''Operation'' (game), a battery-operated board game that challenges dexterity
* Operation (music), a term used in musical set theory
* ''Operations'' (magazine), Multi-Man ...
''. ''Object-oriented programming'' is executing ''operations'' on ''objects''.
''Object-oriented languages'' support a syntax to model
subset/superset relationships. In
set theory
Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly concern ...
, an
element of a subset inherits all the attributes contained in the superset. For example, a student is a person. Therefore, the set of students is a subset of the set of persons. As a result, students inherit all the attributes common to all persons. Additionally, students have unique attributes that other persons don't have. ''Object-oriented languages'' model ''subset/superset'' relationships using
inheritance
Inheritance is the practice of receiving private property, titles, debts, entitlements, privileges, rights, and obligations upon the death of an individual. The rules of inheritance differ among societies and have changed over time. Of ...
.
''Object-oriented programming'' became the dominant language paradigm by the late 1990s.
C++ (1985) was originally called "C with Classes."
It was designed to expand
C's capabilities by adding the object-oriented facilities of the language
Simula.
An object-oriented module is composed of two files. The definitions file is called the
header file. Here is a C++ ''header file'' for the ''GRADE class'' in a simple school application:
// grade.h
// -------
// Used to allow multiple source files to include
// this header file without duplication errors.
// ----------------------------------------------
#ifndef GRADE_H
#define GRADE_H
class GRADE ;
#endif
A
constructor operation is a function with the same name as the class name.
It is executed when the calling operation executes the
new
statement.
A module's other file is the ''
source file''. Here is a C++ source file for the ''GRADE class'' in a simple school application:
// grade.cpp
// ---------
#include "grade.h"
GRADE::GRADE( const char letter )
int GRADE::grade_numeric( const char letter )
Here is a C++ ''header file'' for the ''PERSON class'' in a simple school application:
// person.h
// --------
#ifndef PERSON_H
#define PERSON_H
class PERSON ;
#endif
Here is a C++ ''source file'' for the ''PERSON class'' in a simple school application:
// person.cpp
// ----------
#include "person.h"
PERSON::PERSON ( const char *name )
Here is a C++ ''header file'' for the ''STUDENT class'' in a simple school application:
// student.h
// ---------
#ifndef STUDENT_H
#define STUDENT_H
#include "person.h"
#include "grade.h"
// A STUDENT is a subset of PERSON.
// --------------------------------
class STUDENT : public PERSON;
#endif
Here is a C++ ''source file'' for the ''STUDENT class'' in a simple school application:
// student.cpp
// -----------
#include "student.h"
#include "person.h"
STUDENT::STUDENT ( const char *name ):
// Execute the constructor of the PERSON superclass.
// -------------------------------------------------
PERSON( name )
Here is a driver program for demonstration:
// student_dvr.cpp
// ---------------
#include
#include "student.h"
int main( void )
Here is a
makefile
In software development, Make is a build automation tool that automatically builds executable programs and libraries from source code by reading files called ''Makefiles'' which specify how to derive the target program. Though integrated ...
to compile everything:
# makefile
# --------
all: student_dvr
clean:
rm student_dvr *.o
student_dvr: student_dvr.cpp grade.o student.o person.o
c++ student_dvr.cpp grade.o student.o person.o -o student_dvr
grade.o: grade.cpp grade.h
c++ -c grade.cpp
student.o: student.cpp student.h
c++ -c student.cpp
person.o: person.cpp person.h
c++ -c person.cpp
See also
*
Functional programming
In computer science, functional programming is a programming paradigm where programs are constructed by applying and composing functions. It is a declarative programming paradigm in which function definitions are trees of expressions tha ...
*
Comparison of programming paradigms
*
Reactive programming
*
History of programming languages
*
List of imperative programming languages
Notes
References
* Pratt, Terrence W. and
Marvin V. Zelkowitz. ''Programming Languages: Design and Implementation'', 3rd ed. Englewood Cliffs, N.J.: Prentice Hall, 1996.
* Sebesta, Robert W. ''Concepts of Programming Languages'', 3rd ed. Reading, Mass.: Addison-Wesley Publishing Company, 1996.
: ''Originally based on the article 'Imperative programming' by Stan Seibert, from
Nupedia, licensed under the
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{{DEFAULTSORT:Imperative Programming
Programming paradigms