下面是我写的一个计算升高的程序，我开始没加while((getchar=())!='\n')，然后程序运行到一半，就会自动地输出下面的部分。请教了下别人，说因为没清空缓冲区，可是在什么情况下需要清空输入缓冲区，还有输入缓冲区不是会被下次的输入覆盖吗？求教

#include<stdio.h>
main()
{
    char sex,sports,diet;
    int h,fh,mh,c;
    printf("Hello,welcome to the test of how tall will you be\n");

    printf("how tall are you father?\n");
    scanf("%d",&fh);

    printf("how tall are you mather?\n");
    scanf("%d",&mh);
    while((c=getchar())!='\n');

    printf("May I ask you gender?please print F or M\n");
    scanf("%c",&sex);
    while((c=getchar())!='\n');

    printf("Do you like playing sports?Y or N\n");
    scanf("%c",&sports);
    while((c=getchar())!='\n');

    printf("Do you have healthy habit?Y or N\n");
    scanf("%c",&diet);
    while((c=getchar())!='\n');

    if(sex=='M'||sports=='m')
    {
        h=(fh+mh)*0.54;
        if(sports=='Y'||sports=='y')
            h=h*1.02;
        if(diet=='Y'||diet=='y')
            h=h*1.015;
        printf("You will be %d\n",h);
    }
    else if(sex=='F'||sex=='f')
    {
        h=(fh*0.923+mh)/2;
        if(sports=='Y'||sports=='y')
            h=h*1.02;
        if(diet=='Y'||diet=='y')
            h=h*1.015;
        printf("You will be %d\n",h);

        while(getchar()!='\n');
        getchar();


    }
    return 0;
}

哦哦，谢谢了