我也怀疑是那，但是我改成这样    printf("\t       please enter you choice:\n");
    scanf("%d", &i);

switch(i)
{
case 1:input data;break
case 2:output data;break
case 3:insert data;break
case 4:Delete data;break
case 0:quit system;break
default:input error;
}
}
错误更多了……

我也怀疑是那，但是我改成这样  
  printf("\t       please enter you choice:\n");
    scanf("%d", &i);

switch(i)
{
case 1:input data;break
case 2:output data;break
case 3:insert data;break
case 4:Delete data;break
case 0:quit system;break
default:input error;
}
}
错误更多了……

#include <stdio.h>
 void main()
 {
     int i;
     printf("\t\t--------------------------------------\n");
 printf("\t        the menu of the data management\n");
 printf("\t              1. input data\n");
 printf("\t              2. otput data\n");
printf("\t              3. insert data\n");
 printf("\t              4. delete data\n");
 printf("\t              0. quit system\n");
     printf("\t\t--------------------------------------\n");
     printf("\t       please enter you choice:\n");
     scanf("%d", &i);
 
 switch(i){
 case 1:printf("input data\n");break;
 case 2:printf("output data\n");break;
 case 3:printf("insert data\n");break;
 case 4:("Delete data;break\n");
 case 0:printf("quit system\n");break;
 default:printf("input error");}}
修改好了可以运行，你自己对照看一下！！！！

再次看到这种问题了
你将条件改下不就可以了  看看3楼的

我刚刚翻书了 想了想错误对着书上的格式来了一遍就对了。
#include <stdio.h>
void main()
{
    int i;
    printf("\t\t--------------------------------------\n");
printf("\t        the menu of the data management\n");
printf("\t              1. input data\n");
printf("\t              2. otput data\n");
printf("\t              3. insert data\n");
printf("\t              4. delete data\n");
printf("\t              0. quit system\n");
    printf("\t\t--------------------------------------\n");
    printf("\t       please enter you choice:\n");
    scanf("%d", &i);

switch(i)
{
   
case 1: printf("input data\n");break;
case 2: printf("output data\n");break;
case 3: printf("insert data\n");break;
case 4: printf("Delete data\n");break;
case 0: printf("quit system\n");break;
default :printf("input error\n");
}
}

c中貌似没有input，output那些语句···

#include <stdio.h>
int main()
{
int i,j;
for (i=1;i<=9;i++)
{
for (j=1;j<=10-i;j++)
printf("%d*%d=%2d ",j,i,j*i);
printf("\n");
}
}

#include <stdio.h>

int main()
{
    int i, j;
    for(i=9;i>0;i--)
    {
    for(j=1;j<i+1;j++)
        printf("%d*%d=%d\t",j,i,i*j);
    printf("\n");
    }
}

综合楼上的花括号问题，再补多一个break后面加分号；

观摩