w3resource

C Exercises: Find the missing number from a given array

C Array: Exercise-36 with Solution

Write a program in C to find the missing number in a given array. There are no duplicates in the list.

Visual Presentation:

C Exercises: Find the missing number from a given array

Sample Solution:

C Code:

#include <stdio.h>

// Function to find the missing number in an array
int pickMissNumber(int *arr1, int ar_size) {
    int i, sum = 0, n = ar_size + 1;

    // Calculating the sum of all elements in the array
    for (i = 0; i < ar_size; i++) {
        sum = sum + arr1[i];
    }

    // Calculating the missing number using the sum of the first 'n' natural numbers formula
    return (n * (n + 1)) / 2 - sum;
}

// Main function
int main() {
    int i;
    int arr1[] = {1, 3, 4, 2, 5, 6, 9, 8};
    int ctr = sizeof(arr1) / sizeof(arr1[0]);

    // Displaying the given array
    printf("The given array is :  ");
    for (i = 0; i < ctr; i++) {
        printf("%d  ", arr1[i]);
    }
    printf("\n");

    // Finding and displaying the missing number
    printf("The missing number is : %d \n", pickMissNumber(arr1, ctr));

    return 0;
}

Sample Output:

The given array is :  1  3  4  2  5  6  9  8  
The missing number is : 7 

Flowchart :

Flowchart: Find the missing number from a given array.

C Programming Code Editor:

Previous: Write a program in C to find the largest sum of contiguous subarray of an array.
Next: Write a program in C to find the pivot element of a sorted and rotated array using binary search

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Follow us on Facebook and Twitter for latest update.