Selection Criteria for a Programming Language
1. Usability
Easy to learn, ease of use for an experienced programmer.
2. Performance
Speed of program execution, speed of compiler execution (a program which translates the program into machine code), stability (lack of defects).
3. Portability
A portable language is one which is implemented in variety of computers (design relatively machine dependent). Well defined language are more portable than others e.g. C, C++.
4. Extendibility
Possibility of developing the language and its implementation, existence function libraries, class libraries, etc.
5. Continuity
Continuity of the manufacturer, language continuity, implementation continuity, existence of international standards for defining the language, comformity of implementation by following standards, existence of other manufacturers for that language.
Subprograms
In computer science, a subroutine or subprogram (also called procedure, method, function, or routine) is a portion of code within a larger program, which performs a specific task and is relatively independent of the remaining code.
As the name "subprogram" suggests, a subroutine behaves in much the same way as a computer program that is used as one step in a larger program or another subprogram.
A subroutine is often coded so that it can be started ("called") several times and/or from several places during a single execution of the program, including from other subroutines, and then branch back (return) to the next instruction after the "call" once the subroutine's task is done.
There are two distinct categories of subprograms:
1. Procedures 2. Functions.