While loop in C / C++ with examples
In this tutorial, we will learn about the C / C++ while
loop and its working with the help of some examples. This is one of the basic knowledge in C / C++ programming language, so please learn it carefully.
Top 20 while loop in C / C++ with examples
Here, we will implement examples using while
loop in C / C++ from basic to advanced. For each example, we will implement with two different languages C and C++.
Example 1: Printing numbers from 1 to 200 with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int i = 1; cout<<"Numbers from 1 to 200:\n "; while (i <= 200) { cout << i << " "; i++; } cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> int main(void) { int i = 1; printf("Numbers from 1 to 200: \n"); while (i <= 200) { printf("%d ", i); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 2: Displaying a text 10 times with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int i = 1; cout<<"Displaying a text 10 times with for while in C / C++. \n\n"; while (i <= 10) { cout <<"Hello, I'm learnc.net\n"; i++; } cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> int main(void) { int i = 1; printf("Displaying a text 10 times with for while in C / C++. \n\n"); while (i <= 10) { printf("Hello, I'm learnc.net\n"); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 3: Find the sum of first n Natural Numbers with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int num, sum, i = 1; sum = 0; cout << "Enter a positive integer: "; cin >> num; while(i <= num) { sum += i; i++; } cout << "Sum = " << sum << endl; cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> int main(void) { int num, sum, i = 1, j = 1; sum = 0; printf("Enter a positive integer: "); scanf("%d", &num); printf("Numbers from 1 to %d: ",num); while (j <= num) { printf("%d ", j); j++; } while (i <= num) { sum += i; i++; } printf("\nSum = %d\n", sum); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 4: Display elements of array using while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int arr[]={19, 2, 17, 1, 2000, 2003}; int i = 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<6){ cout<<arr[i]<<" "; i++; } cout<<"\n\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> int main(void) { int arr[]={19, 2, 17, 1, 2000, 2003}; int i = 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<6){ printf("%d ",arr[i]); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 5: Displaying even numbers from 1 to n with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int n, i = 1; cout<<"Enter number n: "; cin>>n; cout<<"Even numbers from 1 to "<< n<<" is: \n"; while(i <= n){ if(i % 2 == 0) cout<<i<<" "; i++; } 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 n, i = 1; printf("Enter number n: "); scanf("%d", &n); printf("Even numbers from 1 to %d is: ", n); while(i <= n){ if(i % 2 == 0) printf("%d ", i); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 6: Displaying odd numbers from 1 to n with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int n, i = 1; cout<<"Enter number n: "; cin>>n; cout<<"Odd numbers from 1 to "<< n<<" is: \n"; while(i <= n){ if(i % 2 == 1) cout<<i<<" "; i++; } 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 n, i = 1; printf("Enter number n: "); scanf("%d", &n); printf("Odd numbers from 1 to %d is: ", n); while(i <= n){ if(i % 2 == 1) printf("%d ", i); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 7: Displaying primes from 1 to n with while loop 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 n, i = 1; cout<<"Enter number n: "; cin>>n; cout<<"Primes from 1 to "<< n<<" is: \n"; while(i <= n){ if(isPrimes(i)) cout<<i<<" "; i++; } 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 n, i = 1; printf("Enter number n: "); scanf("%d", &n); printf("Primes from 1 to %d is: ", n); while(i <= n){ if(isPrimes(i)) printf("%d ", i); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 8: Displaying even numbers in array with while loop 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:
Example 9: Displaying odd numbers in array with while loop 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:
Example 10: Displaying primes numbers in array with while loop 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:
Example 11: Find the sum of elements in array with while loop C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int sum = 0, i = 0, j = 0; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ sum += arr[j]; j++; } cout<<"\nSum of elements in array: "<<sum; cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> #include <stdbool.h> int main(void) { int sum = 0, i = 0, j = 0; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ sum += arr[j]; j++; } printf("\nSum of elements in array: %d",sum); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 12: Find the sum of even elements in array with while loop C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int sum = 0, i = 0, j = 0;; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ if(arr[j] % 2 == 0) sum += arr[j]; j++; } cout<<"\nSum of even elements in array: "<<sum; cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> #include <stdbool.h> int main(void) { int sum = 0, i = 0, j = 0; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ if(arr[j] % 2 == 0) sum += arr[j]; j++; } printf("\nSum of even elements in array: %d",sum); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 13: Find the sum of odd elements in array with while loop C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int sum = 0, i = 0, j = 0;; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ if(arr[j] % 2 == 1) sum += arr[j]; j++; } cout<<"\nSum of odd elements in array: "<<sum; cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> #include <stdbool.h> int main(void) { int sum = 0, i = 0, j = 0; int arr[]={1, 5, 9, 7, 11, 2, 10, 6, 7}; /* 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++; } while(j<9){ if(arr[j] % 2 == 1) sum += arr[j]; j++; } printf("\nSum of odd elements in array: %d",sum); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 14: Dislaying the multiplication table with while loop C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int n, i = 1; cout<<"Enter number n: "; cin>>n; while(i<= 9){ cout<<n<<" x " <<i<<" = "<<n*i<<"\n"; i++; } cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> #include <stdbool.h> int main(void) { int n, i = 0; printf("Enter number n: "); scanf("%d", &n); while(i<= 9){ printf("%d x %d = %d\n",n,i,n*i); i++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 15: Import and export elements in an array with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; int main() { int n, i = 0, j = 0; cout<<"Enter the number of elements in the array: "; cin>>n; int numbers[n]; while(i < n){ cout << "Enter elements, i = : "; cin >> numbers[i]; i++; } cout<<"\nElements in array: "; while (j < n){ cout << numbers[j] << " "; j++; } cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> int main(void) { int n, i = 0, j = 0; printf("Enter the number of elements in the array: "); scanf("%d", &n); int numbers[n]; while (i < n){ printf("Enter elements, i = : "); scanf("%d",&numbers[i]); i++; } printf("\nElements in array: "); while (j < n){ printf("%d ",numbers[j]); j++; } printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 16: Sort array ascending with while loop in C / C++
C++ programming:
#include <iostream> using namespace std; void sort_numbers_ascending(int number[], int count) { int temp, i, j, k; for (j = 0; j < count; ++j) { for (k = j + 1; k < count; ++k) { if (number[j] > number[k]) { temp = number[j]; number[j] = number[k]; number[k] = temp; } } } cout<<"\n\nArray after sorting: "; for (i = 0; i < count; ++i) cout<<" "<< number[i]; } int main() { int n, i = 0, j = 0, k = 0; int sum = 0; cout<<"Enter the number of elements in the array: "; cin>>n; int numbers[n]; while(i < n){ cout << "Enter elements, i = : "; cin >> numbers[i]; i++; } cout<<"\nElements in array: "; while (j < n){ cout << numbers[j] << " "; j++; } sort_numbers_ascending(numbers,n); cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> void sort_numbers_ascending(int number[], int count) { int temp, i, j, k; for (j = 0; j < count; ++j) { for (k = j + 1; k < count; ++k) { if (number[j] > number[k]) { temp = number[j]; number[j] = number[k]; number[k] = temp; } } } printf("\n\nArray after sorting: "); for (i = 0; i < count; ++i) printf("%d ",number[i]); } int main(void) { int n, i = 0, j = 0, k = 0; int sum = 0; printf("Enter the number of elements in the array: "); scanf("%d", &n); int numbers[n]; while (i < n){ printf("Enter elements, i = : "); scanf("%d",&numbers[i]); i++; } printf("\nElements in array: "); while (j < n){ printf("%d ",numbers[j]); j++; } sort_numbers_ascending(numbers,n); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output:
Example 17: Sort array descending with while loop in C/C++
C++ programming:
#include <iostream> using namespace std; void sort_numbers_descending(int number[], int count) { int temp, i, j, k; for (j = 0; j < count; ++j) { for (k = j + 1; k < count; ++k) { if (number[j] < number[k]) { temp = number[j]; number[j] = number[k]; number[k] = temp; } } } cout<<"\n\nArray after sorting: "; for (i = 0; i < count; ++i) cout<<" "<< number[i]; } int main() { int n, i = 0, j = 0, k = 0; int sum = 0; cout<<"Enter the number of elements in the array: "; cin>>n; int numbers[n]; while(i < n){ cout << "Enter elements, i = : "; cin >> numbers[i]; i++; } cout<<"\nElements in array: "; while (j < n){ cout << numbers[j] << " "; j++; } sort_numbers_descending(numbers,n); cout<<"\n-------------------------------\n"; cout<<"This program is posted at learnnc.com"; return 0; }
C programming:
#include <stdio.h> void sort_numbers_descending(int number[], int count) { int temp, i, j, k; for (j = 0; j < count; ++j) { for (k = j + 1; k < count; ++k) { if (number[j] < number[k]) { temp = number[j]; number[j] = number[k]; number[k] = temp; } } } printf("\n\nArray after sorting: "); for (i = 0; i < count; ++i) printf("%d ",number[i]); } int main(void) { int n, i = 0, j = 0, k = 0; int sum = 0; printf("Enter the number of elements in the array: "); scanf("%d", &n); int numbers[n]; while (i < n){ printf("Enter elements, i = : "); scanf("%d",&numbers[i]); i++; } printf("\nElements in array: "); while (j < n){ printf("%d ",numbers[j]); j++; } sort_numbers_descending(numbers,n); printf("\n-------------------------------\n"); printf("This program is posted at learnnc.com"); return 0; }
Output: