#include <stdio.h>
#include <math.h>

int pow_i(int base, int exp){
    int result = 1;
    while (exp){
        if (exp & 1)
            result *= base;
        exp >>= 1;
        base *= base;
    }
    return result;
}

float round_float_precision(float x, unsigned digits){
	unsigned precision = pow_i(10, digits);
	return roundf(x*precision)/precision;
}

int main(void) {
	float x = 123.456;
	printf("Two digits of precision\n");
	printf("- by printf                  - %.2f\n", x);
	printf("- by setting value precision - %f\n", round_float_precision(x, 2));
	return 0;
}