修改程序
int cton()  
{  
char ch;  
int n=0,f=0,n1=0;  
while((ch==getchar())<= "0"||ch>= "9")  
{
n1++;  
if(n1>=10)  
{
printf( "data is wrong !");
return 0;
}
}
do  
   {
n=n/10+ch-'0';
}  
while((ch==getchar())>= "0"&ch<= "9");  
return n;  
}