Decision Making Statements

August 26, 2020

Decision Making Statements

1. The if Statement

It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.

Syntax:

if(expression){
//code to be executed
}

Example:

#include<stdio.h>
int main()
{
	int age;
	printf("Enter your age: ");
	scanf("%d",&age);
	if(age>=18){
		printf("You are eligible to vote.");
	}
	printf("Thank you!");
	return 0;
}

Output:

Enter your age: 18
You are eligible to vote.
Thank you!

2. The if-else Statement

if(expression){
//code to be executed if condition is true
}else{
//code to be executed if condition is false
}

Example:

#include<stdio.h>
int main()
{
	int n1,n2;
	printf("Enter two numbers:");
	scanf("%d %d",&n1,&n2);
	if(n1>n2){
		printf("%d is greater.",n1);
	}
	else{
		printf("%d is greater.",n2);
	}
	return 0;
}

Output

Enter two numbers:7 11
11 is greater.

3. The if-else-if Ladder Statement

Syntax:

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 if(conditionN){
//code to be executed if conditionN is true
}
else{
//code to be executed if all the conditions are false
}

4. The nested if Statement

Nested if statements means an if statement inside another if statement.

Syntax:

if (condition1)
{
   // Executes when condition1 is true
   if (condition2)
   {
      // Executes when condition2 is true
   }
}

5. The nested if-else Statement

/*Program to check if two numbers are equal,
greater or less than to each other*/
#include <stdio.h>
int main()
{
   int num1, num2;
   printf("Enter the value of num1:");
   scanf("%d", &num1);
   printf("Enter the value of num2:");
   scanf("%d",&num2);
   if (num1 != num2)
   {
	printf("num1 is not equal to num2\n");
	//Nested if else
	if (num1 > num2)
	{
		printf("num1 is greater than num2\n");
	}
	else
	{
		printf("num2 is greater than num1\n");
	}
   }
   else
   {
	printf("num1 is equal to num2\n");
   }
   return 0;
}

Output:

Enter the value of num1:11
Enter the value of num2:29
num1 is not equal to num2
num2 is greater than num1