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condition in c language

C Language If , If else , Nested If else Statement with examples

C Language Decisions Control Statement:

In decision control statements (C if else and nested if), group of statements are executed when condition is true.

If condition is false, then else part statements are executed.

There are 3 types of decision making control statements in C language. They are,

  1. If statements
  2. If else statements
  3. Nested if statements

“If”, “else” and “nested if” decision control statements in C:

Syntax for each C Language decision control statements are given below table with description.

 

DecisionsSyntaxDescription
ifif (condition-here) {
statement;
}
In these type of statements, if condition is true,
{ statement;}
then respective block (statement) of code is executed.
if_elseif (condition-here) {
statement-1;
statement-2;
}
else {
statement-3;
}
In these type of statements, group of statements are
{ statement-1; statement-2}
executed when condition is true. If condition is false, then
{ statement-3;}
else part (statement-3) statements are executed.

nested ifif (condition-1) {
Statement-1;
}
else_if (condition-2) {
Statement-2;
}
else_if (condition-3) {
Statement-3;
}
else {
default-statement;
}
if condition-1 is false, then condition-2 is checked and statements are executed if it is true. If condition 2 also gets failure, then else part is executed.

 

C if Statement :

In “if” control statement, respective block of code is executed when condition is true.

#include <stdio.h>
int main()
{
  int m=40,n=40;
  if (m == n) {
      printf("m and n are equal");
  }
return 0;
}

In above program we use two number and we use also condition if m and n are equal then simply print “m and n are equal”.

OUTPUT : m and n are equal

 

Example 2 :program for if statement in C:

* Write a C program to print the number entered by user only if the number entered is negative.

#include<stdio.h>
int main()
{
int num;
printf("enter number to check:");
scanf("%d",&num);
if(num<0)
{
printf("number is=%d\n",num);
}
printf("the if statement is easy in c programming");
return 0;
}

OUTPUT 1 : enter a number to check:

INPUT 1 : -5

OUTPUT 2 : number is=-5

OUTPUT 2 :the if statement is easy in c programming.

EXPLANATION :

When user enters -5 then, the test expression (num<0) becomes true.

Hence, Number = -5 is displayed in the screen

 

C if_else Statement:

The if_else statement is used if the programmer wants to execute some statement/s when the test expression is true and execute some other statement/s if the test expression is false.

Example 1:  program for if else statement in C:

#include <stdio.h>
int main()
{
  int m=40,n=20;
  if (m == n) {
      printf("m and n are equal");
  }
  else {
        printf("m and n are not equal");
  }
}

OUTPUT :

m and n are not equal

Example 2:  program for if else statement in C:

* Write a C program to check whether a number entered by user is even or odd.

#include <stdio.h>
int main(){
      int num;
      printf("Enter a number you want to check.\n");
      scanf("%d",&num);
      if((num%2)==0)          //checking whether remainder is 0 or not.
           printf("%d is even.",num);
      else
           printf("%d is odd.",num);
      return 0;
}

OUTPUT 1: Enter a number you want to check.

INPUT 1 : 25

OUTPUT 2 : 25 is odd.

Another output

OUTPUT 1 : Enter a number you want to check.

INPUT 1 : 2

OUTPUT 2 : 2 is even.

 

Nested if_else statement (if_else-if_else Statement):

The nested if…else statement is used when program requires more than one test expression.

Example 1:  program for nested if statement in C:

 In “nested if” control statement, if condition 1 is false, then condition 2 is checked and statements are executed if it is true.

If condition 2 also gets failure, then else part is executed.

#include <stdio.h>
int main()
{
  int m=40,n=20;
  if (m>n) {
      printf("m is greater than n");
  }
  else if(m<n) {
        printf("m is less than n");
  }
  else {
        printf("m is equal to n");
  }
}

OUTPUT : m is greater then n

Example 2:   Program for nested if else statement:

* Write a C program to relate two integers entered by user using = or > or < sign.

#include <stdio.h>
int main(){ 
     int numb1, numb2;
     printf("Enter two integers to check\n");
     scanf("%d %d",&numb1,&numb2); 
     if(numb1==numb2) {//checking whether two integers are equal.
          printf("Result: %d = %d",numb1,numb2);
       }
     else if(numb1>numb2) { //checking whether numb1 is greater than numb2. 
          printf("Result: %d > %d",numb1,numb2);
       } 
        else {
           printf("Result: %d > %d",numb2,numb1);
       } 
return 0; 
} 

OUTPUT 1 : Enter two integers to check.

INPUT 1 : 5

INPUT 2: 3

OUTPUT 2 : Result: 5 > 3

 

Second Output Example :

OUTPUT 1 : Enter two integers to check.

INPUT 1 : 4

INPUT 2 : 4

OUTPUT 2 : Result: -4 = -4

hassan

A Freelancer web developer, graphic designer and own this blog to spread knowledge.My hobby is computer problem's solving and i love to help other in this field.

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