Subprograms

In General: the program compound of main part called the main program and secondary part called subprograms.
Subprogram : is an independent program put inside the main program to performed a certain action many times, this subprogram written one time and can recall many times, this reduce the length of the program.
Subprograms can be divided into:
1- Subroutines.
2- Functions.
1- Subroutines: it is an independent program put after the end statement of the main program and consists of a certain numbers of statements. The subroutine terminated with return statement which referred to return to the main program .
The general form of the subroutine is:

No. of statement in main program GOSUB no. of statement of starting subroutine
.
.
.
End statement of main program
No. of statement of subroutine …..
.
.
No. of statement of ending subroutine RETURN
Such as:
10 READ A,B,C
20 DATA 5,10,15
30 GOSUB 100
40 PRINT X
50 END
100 REM FIND THE SUMATION
110 X = A+B+C
120 RETURN