1、

#include <stdio.h>

int main(void)
{
    FILE *fp;
    char name[128];
    double height, weight;
    
    
    if((fp = fopen("a.txt", "w")) == NULL)
        printf("\aFile open failed.\n");
    else
    {
        int i;
        for(i = 0; i < 6; i++)
        {
            printf("NO%d.name = 
 
", i + 1); scanf("%s", name);
            printf("NO%d.height = ", i + 1); scanf("%lf", &height);
            printf("NO%d.weight = ", i + 1); scanf("%lf", &weight);
            fprintf(fp, "%s %.2f %.2f\n", name, height, weight);
        }
        fclose(fp);
    }
    return 0;
}

2、

#include <stdio.h>

int
 
 main(void)
{
    FILE *fp;
    
    typedef struct{
        char name[128];
        double height;
        double weight;
    }Type1;
    
    int i;
    Type1 x[6];
    
    if((fp = fopen("a.txt", "w")) == NULL)
        printf("\aFile open failed.\n");
    else
    {
        for(i = 0; i < 6; i++)
        {
            printf(
 
"x[%d].name = ", i); scanf("%s", x[i].name);
            printf("x[%d].height = ", i); scanf("%lf", &x[i].height);
            printf("x[%d].weight = ", i); scanf("%lf", &x[i].weight);
            fprintf(fp, "%s %.2f %.2f\n", x[i].name, x[i].height, x[i].weight);
        }
        fclose(fp);
    }
    return;
}