C Exercises: Calculate the number of 1's in their binary representation and return them as an array

C Programming Mathematics: Exercise-14 with Solution

For a non negative integer in the range 0 ≤ i ≤ n write a C program to calculate the number of 1's in their binary representation and return them as an array.

Example:
Input:
Number: 7
Number of 1's in the binary representation:
0: 0
1: 1
2: 1
3: 2
4: 1
5: 2

Sample Solution:

C Code:

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

int* count_Bits(int num, int* returnSize) {
    int *p, i;
    
    p = malloc((num + 1) * sizeof(int));
   *returnSize = num + 1;
    
    p[0] = 0;
    for (i = 1; i <= num; i ++) {
        p[i] = p[i & (i - 1)] + 1;   
    }
    
    return p;
}

int main(void)
{
    int *p;
    int returnSize;
    int i = 7;
    printf("Number: %d",i);
    printf("\nNumber of 1's in the binary representation:\n");
	p = count_Bits(5, &returnSize);
    for (i = 0; i < returnSize; i++) {
        printf("%X:\t%d\n", i,  p[i]);
    }
    free(p);
        return 0;
}

Sample Output:

Number: 7
Number of 1's in the binary representation:
0:	0
1:	1
2:	1
3:	2
4:	1
5:	2

Flowchart:

C Programming Code Editor:

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