C Academy · Lesson

Integer and Float Conversions

Precision concerns.

Two Worlds of Numbers

C has integers (exact, no fraction) and floating point (approximate, with fraction). Converting between them changes how a value is stored.

#include <stdio.h>
int main(void) {
    int i = 10;
    double d = 10.5;
    printf("%d %.1f\n", i, d);
    return 0;
}

Most int values fit exactly in a double, so widening is safe.

#include <stdio.h>
int main(void) {
    int n = 1000;
    double d = n;
    printf("d = %.1f\n", d);
    return 0;
}