Question

How to round a number to the nearest power of 2 in C

Answer 1

#include <stdio.h>

unsigned int roundToNearestPowerOf2(unsigned int n) {
    if (n == 0) return 0;

    unsigned int prevPower = 1;
    while (prevPower << 1 <= n) {
        prevPower <<= 1;
    }

    unsigned int nextPower = prevPower << 1;

    return (n - prevPower < nextPower - n) ? prevPower : nextPower;
}

int main() {
    unsigned int num = 37;
    
    printf("Nearest power of 2: %u\n", roundToNearestPowerOf2(num));
}


/*
run:

Nearest power of 2: 32

*/

 

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