#include <stdio.h>
#include <stdlib.h>

int main()
{
    float faHeight,moHeight,yoHeight;
    char sex,sports,diet;
    scanf("%c\n%f\n%f\n%c\n%c",&sex,&faHeight,&moHeight,&sports,&diet);
    if(sex==('M'||'n'))
    {
        yoHeight=(faHeight+moHeight)*0.54;
        if(sports==('Y'||'y'))
        {
             yoHeight*=1+0.02;
             if(diet==('Y'||'y'))
             {
                 yoHeight*=1+0.015;
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
             }
             else
             {
                printf("Your future height will be %.0f(cm)\n",yoHeight);
             }
        }
        else
        {
             if(diet==('Y'||'y'))
            {
                yoHeight*=1+0.015;
                printf("Your future height will be %.0f(cm)\n",yoHeight);
            }
            else
            {
                printf("Your future height will be %.0f(cm)\n",yoHeight);
            }
        }
    }
    else if(sex==('F'||'f'))
{
    yoHeight=(faHeight*0.923+moHeight)/2;
        if(sports==('Y'||'y'))
            {
            yoHeight*=1+0.02;
                if(diet==('Y'||'y'))
                {
                yoHeight*=1+0.015;
                printf("Your future height will be %.0f(cm)\n",yoHeight);
                }
                else
                {
                printf("Your future height will be %.0f(cm)\n",yoHeight);
                }
            }
        else
            {
                if(diet==('Y'||'y'))
                {
                yoHeight*=1+0.015;
                printf("Your future height will be %.0f(cm)\n",yoHeight);
                }
                else
                {
                printf("Your future height will be %.0f(cm)\n",yoHeight);
                }
            }
}

    return 0;
}

#include <stdio.h>

int main()

 {
     double faHeight,moHeight,yoHeight;
     char sex,sports,diet;
     scanf("%c %lf %lf %c %c",&sex,&faHeight,&moHeight,&sports,&diet);
     if(sex == 'M'||sex == 'm')
     {
         yoHeight=(faHeight+moHeight)*0.54;
         if(sports == 'Y'||sports == 'y')
         {
              yoHeight*=1+0.02;
              if(diet == 'Y'||diet == 'y')
              {
                  yoHeight*=1+0.015;
                  printf("Your future height will be %.0f(cm)\n",yoHeight);
              }
              else
              {
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
              }
         }
         else
         {
              if(diet == 'Y'||diet == 'y')
             {
                 yoHeight*=1+0.015;
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
             }
             else
             {
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
             }
         }
     }

 else if(sex == 'F'||sex == 'f')

 {
     yoHeight=(faHeight*0.923+moHeight)/2;
         if(sports == 'Y'||sports == 'y')
             {
             yoHeight*=1+0.02;
                 if(diet == 'Y'||diet == 'y')
                 {
                 yoHeight*=1+0.015;
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
                 }
                 else
                 {
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
                 }
             }
         else
             {
                 if(diet == 'Y'||diet == 'y')
                 {
                 yoHeight*=1+0.015;
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
                 }
                 else
                 {
                 printf("Your future height will be %.0f(cm)\n",yoHeight);
                 }
             }

 }

 else printf("输入有误！");

    return 0;

 } 

好了！你的判断条件太主观了！

程序是对的，可惜算法不科学。

你scanf输入，每次输入你要敲两个回车或一个空格一个回车，看了楼的，他的scanf也不是很好，最好两个格式符之间什么都不要

scanf()中%d和%d之间最好什么都不要加，输入的时候把两个数之间用空格隔开就可以了，1楼的中间有空格，输入的时候容易出问题。如果中间需要加逗号，最好是在输入前面提示下中间用逗号隔开。