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C Exercises: Perform a binary search in an array

C Variable Type : Exercise-12 with Solution

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

Sample Solution:

C Code:

#include<stdio.h>
#include<stdlib.h>

int compare_integers (const void * x, const void * y)
{
  return ( *(int*)x - *(int*)y );
}

int main ()
{
	int * arrItem;
	int findValue;
	int my_array[100];
	int n,i;
       printf("\nInput the number of elements to be stored in the array :");
       scanf("%d",&n);
   
       printf("Input %d elements in the array :\n",n);
       for(i=0;i<n;i++)
        {
	      printf("element - %d : ",i+1);
	      scanf("%d",&my_array[i]);
	    }		
	printf (" Input a value to search : ");
	scanf ("%d", &findValue);
	arrItem = (int*) bsearch (&findValue,
		my_array, n, sizeof (int), compare_integers);
	if (arrItem != NULL)
		printf ("%d is found in the array.\n\n",*arrItem);
	else
		printf ("%d is not found in the array.\n\n",findValue);
	return 0;
}

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:

C Exercises Flowchart: Perform a binary search in an array

C Programming Code Editor:

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C Programming: Tips of the Day

Why do C and C++ compilers allow array lengths in function signatures when they're never enforced?

It is a quirk of the syntax for passing arrays to functions.

Actually it is not possible to pass an array in C. If you write syntax that looks like it should pass the array, what actually happens is that a pointer to the first element of the array is passed instead.

Since the pointer does not include any length information, the contents of your [] in the function formal parameter list are actually ignored.

Ref : https://bit.ly/3fhlvdH