#include<stdio.h>int main(){    int a;    next:scanf("%d",&a);    if(a>100||a<0)    {        printf("成绩错误。\n");    }    else if(a<=100&&a>=90)    {        printf("你的成绩为A\n");    }    else if(a>=80)    {        printf("你的成绩为B\n");    }    else if(a>=70)    {        printf("你的成绩为C\n");    }    else if(a>=60)    {        printf("你的成绩为D\n");    }    else    {        printf("你的成绩为E\n");    }    goto next;}

#include<stdio.h>int main(){    int a,b,c,d,e,f,g,h;   next: printf("输入一个不多于五位的正整数。\n");    scanf("%d",&a);    if(0<=a&&a<9)    {        printf("此数为个位数。\n");        h=a;        printf("它的逆序数为%d\n",h);    }    else if(10<=a&&a<=99)    {        printf("此数为两位数。\n");        c=a/10;        d=a%10;        h=c+d*10;        printf("它的逆序数为%02d\n",h);    }    else if(100<=a&&a<=999)    {        printf("此数为三位数。\n");        c=a/100;        d=a%100/10;        e=a%10;        h=c+d*10+e*100;        printf("它的逆序数为%03d\n",h);    }    else if(1000<=a&&a<=9999)    {        printf("此数为四位数。\n");        c=a/1000;        d=a%1000/100;        e=a%100/10;        f=a%10;        h=c+d*10+e*100+f*1000;        printf("它的逆序数为%04d\n",h);    }    else if(10000<=a&&a<=99999)    {        printf("此数为五位数。\n");        c=a/10000;        d=a%10000/1000;        e=a%1000/100;        f=a%100/10,g=a%10;        h=c+d*10+e*100+f*1000+g*10000;        printf("它的逆序数为%05d\n",h);     }    else    {        printf("超出范围。\n");    }       goto next;}

#include<stdio.h>int main(){    int a,b,c,d,e,f;    next:printf("请输入一个五位数。\n");    scanf("%d",&a);    if(a>=10000&&a<=99999)    {        b=a/10000;c=a%10000/1000;d=a%1000/100;e=a%100/10;f=a%10;        if(b==f&&c==e)        {            printf("此数为回文数。\n");        }        else        {            printf("此数不是回文数。\n");        }    }    else    {        printf("超出范围。\n");    }   goto next;}

#include<stdio.h>int main(){    int x;    float y;    next:printf("请输入一个整数作为X的值。\n");    scanf("%d",&x);    if(x>=0&&x<5)    {        y=-x+2.5;        printf("y=%0.3f",y);    }    else if(x>=5&&x<10)    {        y=2-1.5*(x-3)*(x-3);        printf("y=%0.3f",y);    }    else if(x>=10&&x<20)    {        y=x/2.0-1.5;        printf("y=%0.3f",y);    }    else    {        printf("超出计算范围。\n");    }   goto next;}