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if - else statement in C / C++ with example

In this tutorial, we will learn about if - else statement in C / C++ with examples. These are top examples of how to use if - else statement in C / C++. If you are learning about the if - else statement, it is impossible to ignore it.

First, you need to learn about if - else statement in C/C++. These are the basics to use in the examples.

Top 10 if - else statement in C / C++ with examples

Here, we will give 10 examples of if - else statement in C / C++. These examples are written in two different languages, C and C++.

Example 1: Finding the largest of three numbers with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;

int main() {
  int a, b, c, max;
    cout << "Enter number a = ";
    cin >> a;
    cout << "Enter number b = ";
    cin >> b;
    cout << "Enter number c = ";
    cin >> c;
    max = a;
    if(max < b) {
        max = b;
    }
    if(max < c) {
        max=c; 
    }
    cout << "The largest of the three numbers " << a << ", " << b << ", " << c << " is: " << max;

  cout<<"\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>

int main(void) {
  int a, b, c, max;
    printf("Enter number a = ");
    scanf("%d", &a);
    printf("Enter number b = ");
    scanf("%d", &b);
    printf("Enter number c = ");
    scanf("%d", &c);
    max = a;
    if(max < b) {
        max = b;
    }
    if(max < c) {
        max=c; 
    }
    printf("The largest of the three numbers %d, %d, %d is: %d",a,b,c,max);

  printf("\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 01 PNG

Example 2: Finding the smallest of three numbers with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;

int main() {
  int a, b, c, min;
    cout << "Enter number a = ";
    cin >> a;
    cout << "Enter number b = ";
    cin >> b;
    cout << "Enter number c = ";
    cin >> c;
    min = a;
    if(min > b) {
        min = b;
    }
    if(min > c) {
        min=c; 
    }
    cout << "The smallest of the three numbers " << a << ", " << b << ", " << c << " is: " << min;

  cout<<"\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>

int main(void) {
  int a, b, c, min;
    printf("Enter number a = ");
    scanf("%d", &a);
    printf("Enter number b = ");
    scanf("%d", &b);
    printf("Enter number c = ");
    scanf("%d", &c);
    min = a;
    if(min > b) {
        min = b;
    }
    if(min > c) {
        min = c; 
    }
    printf("The smallest of the three numbers %d, %d, %d is: %d",a,b,c,min);

  printf("\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 02 PNG

Example 3: Checking Even or Odd number with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;

int main() {
  int a;
    cout<<"Enter number a = ";
    cin>>a;

    if(a % 2 == 0)
      cout<<"\n"<<a<<" is the Even number.";
    else
      cout<<"\n"<<a<<" is the Odd number.";

  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>

int main(void) {
  int a;
    printf("Enter number a = ");
    scanf("%d", &a);

    if(a % 2 == 0)
      printf("\n%d is the Even number.", a);
    else
      printf("\n%d is the Odd number.", a);

  printf("\n\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 03 PNG

Example 4: Checking for Negative or Positive numbers with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;

int main() {
  int a;
    cout<<"Enter number a = ";
    cin>>a;

    if(a > 0)
      cout<<"\n"<<a<<" is the Positive numbers.";
    else if(a < 0)
      cout<<"\n"<<a<<" is the Negative number.";
    else
      cout<<"\nThis is zero.";

  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>

int main(void) {
  int a;
    printf("Enter number a = ");
    scanf("%d", &a);

    if(a > 0)
      printf("\n%d is the Positive numbers.", a);
    else if(a < 0)
      printf("\n%d is the Negative number.", a);
    else
      printf("\nThis is zero.");

  printf("\n\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 04 PNG

Example 5: Checking for Primes with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
bool isPrimes(int n)
{
    if (n < 2){
        return false;
    }       
    if (n == 2){
        return true;
    }
    if (n % 2 == 0){
        return false;   
    }
    for (int i = 3; i < (n - 1); i += 2){
        if (n % i == 0){
            return false;
        }   
    }
    return true;
}
 
int main() {
  int a;
  cout<<"Enter number a: ";
  cin>>a;
  if(isPrimes(a))
    cout<<endl<<a<<" is the Primes.";
  else
    cout<<endl<<a<<" is not the Primes.";
   
  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
bool isPrimes(int n)
{
    if (n < 2){
        return false;
    }       
    if (n == 2){
        return true;
    }
    if (n % 2 == 0){
        return false;   
    }
    for (int i = 3; i < (n - 1); i += 2){
        if (n % i == 0){
            return false;
        }   
    }
    return true;
}

int main(void) {
  int a;
  printf("Enter number a: ");
  scanf("%d", &a);
  if(isPrimes(a))
    printf("\n%d is the Primes.",a);
  else
    printf("\n%d is not the Primes.",a);

  printf("\n\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 05 PNG

Example 6: Checking for Perfect Squares with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
bool isPerfectSquares(int n){
  int i = 0;
  while(i*i <= n){
        if(i*i == n){
            return true;
        }
        ++i;
    }
    return false;
}
 
int main() {
  int a;
  cout<<"Enter number a: ";
  cin>>a;
  if(isPerfectSquares(a))
    cout<<endl<<a<<" is the Perfect Squares number.";
  else
    cout<<endl<<a<<" is not the Perfect Squares number.";
   
  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
bool isPerfectSquares(int n){
  int i = 0;
  while(i*i <= n){
        if(i*i == n){
            return true;
        }
        ++i;
    }
    return false;
}

int main(void) {
  int a;
  printf("Enter number a: ");
  scanf("%d", &a);
  if(isPerfectSquares(a))
    printf("\n%d is the Perfect Squares number.",a);
  else
    printf("\n%d is not the Perfect Squares number.",a);

  printf("\n\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 06 PNG

Example 7: Checking for Perfect number with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
bool isPerfectNumber(int a){
    int sum = 0;
    for(int i=1;i<=a/2;i++){
        if(a%i==0) 
            sum+=i;
    }
    if(sum==a) return true;
    return false;
}
 
int main() {
  int a;
  cout<<"Enter number a: ";
  cin>>a;
  if(isPerfectNumber(a))
    cout<<endl<<a<<" is the Perfect number.";
  else
    cout<<endl<<a<<" is not the Perfect number.";
   
  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
bool isPerfectNumber(int a){
    int sum = 0;
    for(int i=1;i<=a/2;i++){
        if(a%i==0) 
            sum+=i;
    }
    if(sum==a) return true;
    return false;
}

int main(void) {
  int a;
  printf("Enter number a: ");
  scanf("%d", &a);
  if(isPerfectNumber(a))
    printf("\n%d is the Perfect number.",a);
  else
    printf("\n%d is not the Perfect number.",a);

  printf("\n\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 07 PNG

Example 8: Displaying Even numbers in array with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
int main() {
  int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   cout<<"Elements of array: ";
   while(i<9){
      cout<<arr[i]<<" ";
      i++;
   }
   cout<<"\nEven numbers in array: ";
   while(j<9){
      if(arr[j] % 2 == 0)
        cout<<arr[j]<<" ";
      j++;
   }
   
  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
 
int main(void) {
  int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   printf("Elements of array: ");
   while(i<9){
      printf("%d ",arr[i]);
      i++;
   }
   printf("\nEven numbers in array: ");
   while(j<9){
      if(arr[j] % 2 == 0)
        printf("%d ",arr[j]);
      j++;
   }
   
  printf("\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 08 PNG

Example 9: Displaying Odd numbers in array with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
int main() {
  int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   cout<<"Elements of array: ";
   while(i<9){
      cout<<arr[i]<<" ";
      i++;
   }
   cout<<"\nOdd numbers in array: ";
   while(j<9){
      if(arr[j] % 2 == 1)
        cout<<arr[j]<<" ";
      j++;
   }
   
  cout<<"\n\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
 
int main(void) {
  int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   printf("Elements of array: ");
   while(i<9){
      printf("%d ",arr[i]);
      i++;
   }
   printf("\nOdd numbers in array: ");
   while(j<9){
      if(arr[j] % 2 == 1)
        printf("%d ",arr[j]);
      j++;
   }
   
  printf("\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 09 PNG

Example 10: Displaying Primes in array with if - else statement in C / C++

C++ programming:

#include <iostream>
using namespace std;
 
bool isPrimes(int n)
{
    if (n < 2){
        return false;
    }       
    if (n == 2){
        return true;
    }
    if (n % 2 == 0){
        return false;   
    }
    for (int i = 3; i < (n - 1); i += 2){
        if (n % i == 0){
            return false;
        }   
    }
    return true;
}
 
int main() {
  int arr[]={1, 5, 9, 7, 11};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   cout<<"Elements of array: ";
   while(i<5){
      cout<<arr[i]<<" ";
      i++;
   }
   cout<<"\nPrimes in array: ";
   while(j<5){
      if(isPrimes(arr[j]))
        cout<<arr[j]<<" ";
      j++;
   }
   
  cout<<"\n-------------------------------\n";
  cout<<"This program is posted at learnnc.com";
  return 0;
}

C programming:

#include <stdio.h>
#include <stdbool.h>
 
bool isPrimes(int n)
{
    if (n < 2){
        return false;
    }       
    if (n == 2){
        return true;
    }
    if (n % 2 == 0){
        return false;   
    }
    for (int i = 3; i < (n - 1); i += 2){
        if (n % i == 0){
            return false;
        }   
    }
    return true;
}
 
int main(void) {
  int arr[]={1, 5, 9, 7, 11};
  int i = 0, j = 0;
   /* We have set the value of variable i
    * to 0 as the array index starts with 0
    * which means the first element of array 
    * starts with zero index.
    */
   printf("Elements of array: ");
   while(i<5){
      printf("%d ",arr[i]);
      i++;
   }
   printf("\nPrimes in array: ");
   while(j<5){
      if(isPrimes(arr[j]))
        printf("%d ",arr[j]);
      j++;
   }
   
  printf("\n-------------------------------\n");
  printf("This program is posted at learnnc.com");
  return 0;
}

Output:

exam 10 PNG

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