C Programming Tutorial
The if statement in C language is used to perform operation on the basis of condition. By using if-else statement, you can perform operation either condition is true or false.
There are many ways to use if statement in C language:
- If statement
- If-else statement
- If else-if ladder
- Nested if
If Statement
The single if statement in C language is used to execute the code if condition is true. The syntax of if statement is given below:
if(expression){ //code to be executed }
Flowchart of if statement in C
Let's see a simple example of c language if statement.
#include<stdio.h> int main(){ int number=0; printf("enter a number:"); scanf("%d",&number); if(number%2==0){ printf("%d is even number",number); } return 0; }
Output
enter a number:4
4 is even number
enter a number:5
If-else Statement
The if-else statement in C language is used to execute the code if condition is true or false. The syntax of if-else statement is given below:
if(expression){ //code to be executed if condition is true }else{ //code to be executed if condition is false }
Flowchart of if-else statement in C
Let's see the simple example of even and odd number using if-else statement in C language.
#include<stdio.h> int main(){ int number=0; printf("enter a number:"); scanf("%d",&number); if(number%2==0){ printf("%d is even number",number); } else{ printf("%d is odd number",number); } return 0; }
Output
enter a number:4
4 is even number
enter a number:5
5 is odd number
If else-if ladder Statement
The if else-if statement is used to execute one code from multiple conditions. The syntax of if else-if statement is given below:
if(condition1){ //code to be executed if condition1 is true }else if(condition2){ //code to be executed if condition2 is true } else if(condition3){ //code to be executed if condition3 is true } ... else{ //code to be executed if all the conditions are false }
Flowchart of else-if ladder statement in C
The example of if-else-if statement in C language is given below.
#include<stdio.h> int main(){ int number=0; printf("enter a number:"); scanf("%d",&number); if(number==10){ printf("number is equals to 10"); } else if(number==50){ printf("number is equal to 50"); } else if(number==100){ printf("number is equal to 100"); } else{ printf("number is not equal to 10, 50 or 100"); } return 0; }
Output
enter a number:4
number is not equal to 10, 50 or 100
enter a number:50
number is equal to 50
C - nested if statements
It is always legal in C programming to nest if-else statements, which means you can use one if or else if statement inside another if or else if statement(s).
Syntax
The syntax for a nested if statement is as follows
if( boolean_expression 1) { /* Executes when the boolean expression 1 is true */ if(boolean_expression 2) { /* Executes when the boolean expression 2 is true */ } }
You can nest else if...else in the similar way as you have nested if statements.
Example
#include <stdio.h> int main () { /* local variable definition */ int a = 500; int b = 700; /* check the boolean condition */ if( a == 500 ) { /* if condition is true then check the following */ if( b == 700 ) { /* if condition is true then print the following */ printf("Value of a is 100 and b is 200\n" ); } } printf("Exact value of a is : %d\n", a ); printf("Exact value of b is : %d\n", b ); return 0; }
When the above code is compiled and executed, it produces the following result
Value of a is 500 and b is 700
Exact value of a is : 500
Exact value of b is : 700