How to get the exact fractional part from a floating point number as an integer?

How to get the exact fractional part from a floating point number as an integer?

trying to extract the exact fractional part from a floating point number.

Use modf() or modff()

double modf(double value, double *iptr);
float modff(float value, float *iptr);

The modf functions break the argument value into integral and fractional parts, ...
C11 §7.12.6.12 2

#include <math.h>

double value = 1.234;
double ipart;
double frac = modf(value, &ipart);

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A better approach for OP's need may be to first round a scaled value and then back into whole and fractional parts.

double value = 254.73;
value = round(value*100.0);
 
double frac = fmod(value, 100);  // fmod computes the floating-point remainder of x/y.
double ipart = (value - frac)/100.0;

printf("%f %f\n", ipart, frac);
254.000000 73.000000

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Ref detail: When OP uses 254.73, this is converted to the nearest float value which may be 254.729995727539....

float f = 254.73;
printf("%.30f\n", f);
// 254.729995727539062500000000000000

You can use sprintf and sscanf to print the value to a string and then extract the fraction. The %*d scans and discards the first integer of the formatted string. A dot is scanned and then the fraction.

#include <stdio.h>        

int main( void)           
{                         
    char fp[30];          
    int fraction;         
    float f = 254.73f;    

    sprintf ( fp, "%.2f", f);
    sscanf ( fp, "%*d.%d", &fraction);
    printf ( "%d\n", fraction);

    return 0;                  
}