Question

How to round a number to a multiple of 8 in C

Answer 1

#include <stdio.h>

// The next highest multiple of eight
unsigned int roundToMultipleOf(unsigned int number, unsigned int roundTo) {
    return (number + (roundTo - 1)) & ~(roundTo - 1);
}

int main() {
  printf("%d\n", roundToMultipleOf(9, 8));
  printf("%d\n", roundToMultipleOf(19, 8));
  printf("%d\n", roundToMultipleOf(71, 8));

  return 0;
}



/*
run:

16
24
72

*/

 

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Answer 2

#include <stdio.h>
#include <math.h>
 
unsigned int roundToMultipleOf(unsigned int number, unsigned int multipleOf) {
    return multipleOf * floor(number / multipleOf);
}
 
int main() {
  printf("%d\n", roundToMultipleOf(9, 8));
  printf("%d\n", roundToMultipleOf(19, 8));
  printf("%d\n", roundToMultipleOf(71, 8));
 
  return 0;
}
 
 
 
/*
run:
 
8
16
64
 
*/

 

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