For example a procedure might print a value or update

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Unformatted text preview: s enclosed within a pair of parentheses. If you do not need or want to pass any arguments to the subprogram, the empty parentheses are still required normally to distinguish the statement as a subprogram call. For example, a statement to call the subprogram which calculates the square root of a number may be a = sqrt (b); Different programming languages may have different syntax for writing the call statement for calling a subprogram. Set of instructions that perform the intended task Subprogram header Subprogram body While executing a program that has one or more subprogram call statements, when the computer encounters a subprogram call statement, the control flow jumps to wherever the subprogram's code is, executes the statements in the subprogram body, then returns to that statement of the calling program which is immediately after the call statement. The flow of control in case of a subprogram call is illustrated in Figure 12.25. Note that the subprogram itself need never be written again, nor need it appear more than once in a program, no matter how often its services may be required. Subprograms may be intrinsic or programmer-written. Intrinsic subprograms (commonly referred to as built-in-functions) are those provided with the language so that the programmer need only call them in a program to have them automatically invoked. There are many functionalities such as those for finding square roots, sines, cosines, logarithms, etc., which are used over and over again by many programmers in their programs. Such functionalities are usually supplied along with a programming language in the form of built-in-functions. On the other hand, programmer-written subprograms are written and used as and when they are needed. Subprograms can also return a value to the calling program. This makes it convenient to use a subprogram to set the value of a variable. For example, in case of our subprogram to calculate the square root of a number, you supply the number as its parameter,, and the, subprogram calculates...
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This document was uploaded on 04/07/2014.

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