Functions in
C TCCICOMPUTERCOACHING.COM
What is Function?
A function
is a group of statements that together perform a task. Every C program has at
least one function, which is main (), and all the most trivial programs
can define additional functions.
The C language is similar to most modern programming
languages in that it allows the use of functions, self-contained
"modules" of code that take inputs, do a computation, and produce
outputs. C functions must be TYPED (the return type and the type of all parameters
specified).
Why do we use Function in programming?
Reason for
functions is to break down a complex program into smaller parts. Suppose we
take example of 4 functions we have, 1. Add 2. Sub 3. Mul 4. Div. We have 2
options. First is we take 4 operations in one programs, which becomes very
lengthy, alsoit’s very tough to find out errors. This lengthy program also
takes more time to load and compile. Second we divide whole programs into
smaller modules. So, one main function then remaining 4 modules are 1.ADD 2.
Sub 3.Mul 4. Div. So, these 4 operations are done in these separate modules,
main function only takes declaration of variables and their input values.
In this
modular system compiler time is less compare to first option. We can easily
find out the errors module wise. Time and space efficiency is good in modular
programming. This module decreases complexity.
Structure of Functions:
Functions
that a programmer writes will generally require a prototype. The mult function
is actually defined below main. Because its prototype is above main, the
compiler still recognizes it as being declared, and so the compiler will not
give an error about mult being undeclared.
There are
main 3 section for Function in C programming:
1.
Declaration or Prototype of Function
2.
Function Call
3.
Definition of Function
Data Type
Function name (Data Type parameter1 name-optional, Data Type parameter2
name-optional); // 1.Declaration or Prototype of Function
Main ()
{Variable
declarion;
Clrscr ();
//Input
variable……..
Scanf(“…….”);
Function
name (parameter name/Parameter value) //2. Function call
//Output
Msg…….
Printf(“…………….”);
Getch();
}
Data Type
Function name (DataType formal parameter1, DataType formal parameter2); // 3. Definition of Function
{
Local variable;
Operation takes place here….
………
………
Return statement ();
}
Declaration();
Main()
{
…..
…..
Function
call();
…..
…..
}
Module1()-definition
{
…..
……
Return();
}
Module2()
{
…….
……..
Return();
}
Here, we can
use more than one module in one programme. Compilation start from main always,
memory allocated as per variable declared, then function calls statement
execute, control transform from main function to called function, there
required operation occurs, last return statement execute, then control jump
from that module to main module, and execution completed there.
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