使用 float

#include <stdio.h>

int main() {
    int id;
    float c, math, english;
    scanf("%d;%f,%f,%f", &id, &c, &math, &english);
    printf("The each subject score of No. %d is %.2f, %.2f, %.2f.\n", id, c, math, english);
    return 0;
}

使用 double

#include <stdio.h>

int main() {
    int id;
    double c, math, english;
    scanf("%d;%lf,%lf,%lf", &id, &c, &math, &english);
    c = (int)(c*100+0.5)/100.0;
    math = (int)(math*100+0.5)/100.0;
    english = (int)(english*100+0.5)/100.0;
    printf("The each subject score of No. %d is %.2lf, %.2lf, %.2lf.\n", id, c, math, english);
    return 0;
}