C Exercises: Perform a binary search in an array

Last update on March 18 2025 13:37:44 (UTC/GMT +8 hours)

12. Binary Search in an Array

Write a C program to perform a binary search in an array.

Sample Solution:

C Code:

#include<stdio.h>      // Include the standard input/output header file.
#include<stdlib.h>     // Include the standard library header file.

// Comparator function used for bsearch.
int compare_integers (const void * x, const void * y)
{
return ( *(int*)x - *(int*)y );
}

int main ()          // Start of the main function.
{
int * arrItem;    // Declare a pointer to int 'arrItem'.
int findValue;    // Declare an integer variable 'findValue'.
int my_array[100];   // Declare an integer array 'my_array' with a maximum size of 100.
int n, i;         // Declare integer variables 'n' and 'i'.

printf("\nInput the number of elements to be stored in the array :");   // Prompt the user to input the number of elements.
scanf("%d",&n);   // Read the user's input and store it in 'n'.

printf("Input %d elements in the array :\n",n);   // Prompt the user to input the elements of the array.
for(i=0;i<n;i++)   // Start of a for loop to iterate over the elements of the array.
    {
printf("element - %d : ",i+1);   // Prompt the user for the value of the current element.
scanf("%d",&my_array[i]);     // Read the user's input and store it in the current element of 'my_array'.
    }

printf (" Input a value to search : ");   // Prompt the user to input a value to search for.
scanf ("%d", &findValue);   // Read the user's input and store it in 'findValue'.

arrItem = (int*) bsearch (&findValue, my_array, n, sizeof (int), compare_integers);   // Search for 'findValue' in 'my_array'.

if (arrItem != NULL)   // If 'arrItem' is not NULL (i.e., if 'findValue' was found in the array).
printf ("%d is found in the array.\n\n",*arrItem);   // Print a message indicating that 'findValue' was found.
else
printf ("%d is not found in the array.\n\n",findValue);   // Print a message indicating that 'findValue' was not found.

return 0;   // Return 0 to indicate successful execution of the program.
}   // End of the main function.

Sample Output:

Input the number of elements to be stored in the array :5                                                     
Input 5 elements in the array :                                                                               
element - 1 : 10                                                                                              
element - 2 : 15                                                                                              
element - 3 : 20                                                                                              
element - 4 : 25                                                                                              
element - 5 : 30                                                                                              
 Input a value to search : 20                                                                                 
20 is found in the array.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to implement binary search recursively on a sorted array of integers.
Write a C program to perform binary search on a sorted array and return the index of the found element.
Write a C program to count the number of comparisons made during a binary search in a large sorted array.
Write a C program to implement binary search on a sorted array of strings using a custom comparator function.

C Programming Code Editor:

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