Thread: getchar from keyboard couldn't be end with the termination condition

There is a program of simple encryption and decryption ,it pass the compile and build,but stop at the running process.No whether how I input character thought keyboard,it couldn't end with the termination condition,let alone could have any result.any friend can give me a look?thanks!

Code:

#include<stdio.h>
#include<string.h>

#define MaxSize 100
typedef struct
{char ch[MaxSize];
int len;
}SqString;

SqString A,B;
void StrAssign(SqString &str,char cstr[])
{int i;
for(i=0;cstr[i]!='\0';i++)
str.ch[i]=cstr[i];
str.len=i;
}


void DispStr(SqString s)
{int i;
if(s.len>0)
{for(i=0;i<s.len;i++)
 printf("%c",s.ch[i]);
printf("\n");}}


SqString EnCrypt(SqString p)     /*algorithm of  encrypt with simple character*/
                                                    /*exchange */ 
{int i=0,j;
SqString q;
while(i<p.len)
{for(j=0;p.ch[i]!=A.ch[j];j++);
if(j>=A.len)
q.ch[i]=p.ch[i];
else
q.ch[i]=B.ch[j];
i++;
}
q.len=p.len;
return q;
}


SqString UnEncrypt(SqString q)        /*reverse of encrypt */
{int i=0,j;
SqString p;
while(i<q.len)
{for(j=0;q.ch[i]!=B.ch[j];j++);
if(j>=B.len)
p.ch[i]=q.ch[i];
else p.ch[i]=A.ch[j];
i++;
}
p.len=q.len;
return p;
}



int main()
{SqString p,q;i
nt i=0,j,k=0,t=0;
char ch;
char s1[MaxSize],s2[MaxSize],s[MaxSize];

do{k1:ch=getchar();        /*initialize s1 without  the same character*/
for(j=0;j<i;j++)
if(ch==s1[j]) goto k1;
s1[i++]=ch;
}while(s1[i-1]!='\0');

printf("\n");

while(k<i-1)                    /*initialize s2 without  the same character,and the */
                                /*length of array s2 should be as the same as  array s1*/ 
{k2:ch=getchar();
for(j=0;j<k;j++)
if(s2[j]==ch) goto k2;
s2[k++]=ch;}
s2[k]='\0';

printf("\n");

do{k3:ch=getchar();                            /* initialize s*/
 for(j=0;s1[j]!='\0'&&s1[j]!=ch;j++);
 if(j>=i-1) 
 {for(j=0;s2[j]!='\0';j++)
 if(ch==s2[j]) goto k3;}
 s[k++]=ch;
 }while(s[k-1]!='\0');

printf("\n");


	 
StrAssign(A,s1);
 StrAssign(B,s2);

 StrAssign(p,s);
 
 printf("加密解密如下:\n");
 printf("原文串:");
 DispStr(p);

q=EnCrypt(p);
 printf("加密串:");
 DispStr(q);

 p=UnEncrypt(q);
 printf("解密串:");
 DispStr(p);

 printf("\n");
 return 0;
}