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OTHER RELATED CONCEPTS
Suppose we are writing a program for solving a trigonometric problem. In the
problem solution, suppose we need to calculate the square root of three numbers at
three different places in the program. We could of course write the steps required
for the calculation of square root each time we need them in the program. But a
much easier way of handling the problem would be to write these steps once and
then refer to them each time we need them. Every programming language provides
a way to do this by defining subprograms. A subprogram is a program written in
such a way that it can be brought into use in other programs and used whenever
needed, without rewriting. A subprogram is referred to by different names in
different programming languages. For example, other names used to refer to
subprograms are subroutines, subprocedures, and functions.
The structure of a subprogram is shown in Figure 12.24. It consists of a header and
a body. The subprogram header, which is the first line of a subprogram, provides a
name for the subprogram and it may optionally specify a list of parameters (also
known as arguments). The subprogram name is used by other programs to refer to
the subprogram when they want to use the subprogram. The parameters are
specific variable names, numeric values, or other data that you want the
subprogram to use as it executes the instructions in its body. The list of parameters
is optional because there may be subprograms for which you do not need or want to pass any arguments. The subprogram body contains the set of instructions that
perform the intended task of the subprogram.
Once created, a subprogram can be used by other programs as often as needed. At
whatever points in a program the function performed by the subprogram is
required, a statement to call the subprogram is inserted by the programmer.
Typically, the subprogram call statement contains the name of the subprogram
followed by the list of parameter...
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This document was uploaded on 04/07/2014.
- Spring '14