Imperative programming

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.

[note 1] 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.

Unconditional branching statements allow an execution sequence to be transferred to another part of a program.

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.

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's target language for some computers.

In the 1970s, Pascal was developed by Niklaus Wirth, and C was created by Dennis Ritchie while he was working at Bell Laboratories.

For the needs of the United States Department of Defense, Jean Ichbiah and a team at Honeywell began designing Ada in 1978, after a 4-year project to define the requirements for the language.

Smalltalk-80, originally conceived by Alan Kay in 1969, was released in 1980, by the Xerox Palo Alto Research Center (PARC).

Fortran 90 supports: COBOL (1959) stands for "COmmon Business Oriented Language."

[5] The US Department of Defense influenced COBOL's development, with Grace Hopper being a major contributor.

[6] COBOL's development was tightly controlled, so dialects did not emerge to require ANSI standards.

[7] Emerging from a committee of European and American programming language experts, it used standard mathematical notation and had a readable structured design.

It added features like: Algol's direct descendants include Pascal, Modula-2, Ada, Delphi and Oberon on one branch.

[8] It offered operating system commands within its environment: However, the Basic syntax was too simple for large programs.

Microsoft's Visual Basic is still widely used and produces a graphical user interface.

It added advanced features like: C allows the programmer to control in which region of memory data is to be stored.

In the 1970s, software engineers needed language support to break large projects down into modules.

[18] One obvious feature was to decompose large projects physically into separate files.

In set theory, an element of a subset inherits all the attributes contained in the superset.

"[24] It was designed to expand C's capabilities by adding the object-oriented facilities of the language Simula.