#include <stdio.h>

double larger_of(double *x, double *y);

int main(void) {
    double m, n;
    printf(" please enter two double data:\n");
    scanf("%lf%lf", &m, &n);
    printf("m=%lf,n=%lf\n", m, n);
    printf("m:%p,n:%p\n", &m, &n);
    larger_of(&m, &n);
    printf("m=%lf,n=%lf\n", m, n);
    printf("m:%p,n:%p", &m, &n);
    return 0;

}

double larger_of(double *x, double *y) {
    double temp;
    *x > *y ? *y = *x : *x = *y;
    return 0;
}

temp参数没用上。

不是排序，是输入2个大小不一的数，然后打印出两个大的数。