C programming functions
In the tutorial, we will discuss function in C programming language with examples. The function is the building block of programming in C language.
Description of function in C programming language
What is a function?
The function is a block of statement or instruction enclosed by curly braces { } that together perform one of the special tasks in C program. Collection of these functions perform a special purpose(inter-connected a lot of tasks) in C program.
return_type function_name (parameter list){
//function body
return (expression)
}
return_type – The return type is a data type used for the function declaration.
Ex – int, float, double, void
Void data type never returns any value but the usage of other data type returns the value.
function_name – function name is used to identify the function in the C Programming language. Every function should have a name(user define function) as the function name represents the uniqueness of function and function name is used to call the function.
parameter_list – A function may contain a parameter list(one or more parameter). Sometimes, functions may not contain a parameter(it is optional). However, when a function is executed, you pass a value(it’s called argument) to the parameter list which refers to the parameter type, order of parameter and number of the parameter of a function.
Function_body – The body of the function consists of a group of statements. They will be invoked when the function is called.
Two types of function available in C language.
Standard library function – standard library functions are built-in functions or predefined functions in C language to handle a special task.
Ex – mathematical operations, I/O processing and string handling etc
These functions are already defined in the header file of C programming language. When they are included in the header file of the program, we can use these function easily.
Ex –
string.h – string handling functions
math.h – Arithmetic operations
The printf() function is a predefined function in C language used to get the output on the screen. This function is defined in “stdio.h” header file.
The scanf() function is a predefined function in C language used to get the input from the user. This function is defined in “stdio.h” header file.
User defined function in C language
C language supports you to define functions according to your needs and satisfaction. These functions are called as user-defined functions in C language
4 type of function available in C Language
Examples
Add two numbers using function(No return without argument)
#include <stdio.h>
#include <stdlib.h>
void add(); //function declaration
void main()
{
add(); //calling function no argument
getch();
return 0;
}
void add()//no argument is passed to this function
{//void data type never return anything from function
int a,b;
printf("Enter first number for a");
scanf("%d",&a);
printf("Enter second number for b");
scanf("%d",&b);
int c=a+b;
printf("total value (a+b) is %d\n",c);
}
When the above program is compiled and run, it will produce the following result
Enter first number for a :45 Enter second number for b :78 Total value (a+b) is 123
Calculating the difference between two numbers using function(No return with argument)
#include <stdio.h>
#include <stdlib.h>
void sub(int f_num, int s_num);//function declaration
int main()
{
sub(67,34);
getch();
return 0;
}
void sub(int f_num, int s_num) //No argument is passed to this function
{ //void data type never return value from function
printf("Enter the first number of a: ");
scanf("%d",&f_num);
printf("Enter the first number of b: ");
scanf("%d",&s_num);
int diff=f_num-s_num;
printf("Total value(a+b) is %d\n",diff);
}
When the above program is compiled and run, it will produce the following result
Enter your first number :67 Enter your second number :34 Different between two numbers :33
Multiplication of two numbers using function(Return without argument)
#include <stdio.h>
#include <stdlib.h>
int mul();//function declaration
int main()
{
printf("Answer is: %d",mul());
getch();
return 0;
}
int mul() //No argument is passed to this function
{ //void data type never return value from function
int f_no, s_no;
printf("Enter the first number of f_no: ");
scanf("%d",&f_no);
printf("Enter the first number of s_no: ");
scanf("%d",&s_no);
return f_no*s_no;
}
When the above program is compiled and run, it will produce the following result
Enter first number for f_no:12 Enter second number for s_no:23 Answer is :276
Multiplication of two numbers using function(Return with arguments
#include <stdio.h>
#include <stdlib.h>
int mul(int a, int b);//function declaration
int main()
{
printf("The result is: %d",mul(45,34));//function calling
getch();
return 0;
}
int mul(int f_no, int s_no) //No argument is passed to this function
{ //void data type never return value from function
printf("Enter the first number of f_no: ");
scanf("%d",&f_no);
printf("Enter the first number of s_no: ");
scanf("%d",&s_no);
return f_no*s_no;//return statements in function
}
When the above program is compiled and run, it will produce the following result
The first number of f_no: 45 The second number of s_no: 100 The result is :4500
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