[FIXED] why does the number 51444.325061 doesnot round off to 51444.325 upto 3 decimal places? I want to round off this number in c programming

Issue

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

int main() {
    float n;
    scanf("%f", &n);
    printf("%.3f", n);
}

input: 51444.325061

my output: 51444.324

expected output: 51444.325

why does I dont get the proper answer?

Solution

32-bit float can encode about 2³² different values.

51444.325061is not one of them^**. Instead the nearest float is exactly 51444.32421875. The next best choice would be 51444.328125.

Printing 51444.32421875 to 3 decimal places is best as "51444.324".

---

why does I dont get the proper answer?

float is too imprecise to encode 51444.325061 as OP desires. Using double will help. The same problem exists, yet only appears when about 16+ significant digits are needed.

---

^** Encodable finite values are of the form: some_integer * 2^{some_exponent}.

Answered By - chux - Reinstate Monica

Answer Checked By - David Goodson (PHPFixing Volunteer)