Functions
in C Programming
Why we need functions in C
a) To improve the readability of code.
b) Improves the reusability of the code, same function
can be used in any program rather than writing the same code from scratch.
c) Debugging of the code would be easier if you use
functions, as errors are easy to be traced.
d) Reduces the size of the code, duplicate set of
statements are replaced by function calls.
A function is a block of statements that performs a
specific task.
Syntax
of a function
return type function name (argument list)
{
Set of
statements – Block of code
}
Defining
a Function in C
The function definition, in general, holds this form
in the C programming language:
return_type name_of_function( parameter list )
{
Function body
}
Function Name
− It denotes the actual name of any function that we are using in the given
code. The name and parameter of a function constitute a function signature in
the code together.
Function Body
− It consists of a collection of all the statements. These provide a definition
of what the function will do in the code.
Parameters
− It is just like a placeholder. Whenever we invoke a function, we pass a value
to the available parameter. We refer to this value as an argument or an actual
parameter. We refer to the parameter list as the number, order, and type of the
function in the code. The parameters may be optional. It means that any
function in a code may consist of no parameters at all.
Return Type
− we may get a value in return for a function. The term return type refers to
the data type of the returns that we get from the functions (function returns).
Some of the functions are also capable of performing any desired operation
without getting a value in return for it. In any such case, the keyword used
for the return type will be void.
Function
Call
When a function gets called by a program, the called
function will get the program control transferred to it. The called function
will be performing a defined task.
When a function gets called by a program, the called
function will get the program control transferred to it. The called function
will be performing a defined task.
// call and definition
#include <stdio.h>
// Function
that takes two parameters
// a and b as inputs and return their sum
int sum(int a, int b)
{
return a + b;
}
// Driver code
int main()
{
// Calling sum
function and
// storing its
value in add variable
int add =
sum(10, 30);
printf("Sum
is: %d", add);
return 0;
}
Function
Arguments
When a function needs to use the arguments, it has to
declare those variables that happen to accept the arguments’ values. Such
variables are known as the given function’s formal parameters.
Call By Reference-The
Call by Reference method creates a copy of the address of the given argument
into the parameter that is formal in nature. Inside this function, the use of
address helps in accessing the actual argument that comes in use in this call.
It means that the changes that appear on the parameter are bound to affect the
given argument.
Call By Value-The
Call by Value method creates a copy of the actual value of the given argument
in the parameter of the function that is formal in nature. Here, the changes
that appear on the parameter (that exists inside the function) create no effect
whatsoever on the available argument.
Milan Tomic
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