Question

How to rotate left by N bits in C

Answer 1

#include <stdio.h>

#define TOTAL_INT_BITS 32

int leftRotate(unsigned num, unsigned total_bits){ 
     return (num << total_bits)|(num >> (TOTAL_INT_BITS - total_bits));
}
 
void print_bits(int n, int size) {
    for (int i = 1 << (size - 1); i > 0; i = i / 2)
        (n & i) ? printf("1") : printf("0");
}
 
int main(void)
{
    unsigned int num = 21791;
    
    print_bits(num, 16);
    
    int N = 3;
    
    num = leftRotate(num, N);
    
    printf("\n");
    
    print_bits(num, 16);
 
    return 0;
}
 
 
 
 
/*
run:
 
0101010100011111
1010100011111000
 
*/

 

 

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