请问这个程序为什么没法输出?
#include<stdio.h>
void squeeze(char s1[],char s2[])
{
int i, j, k = 0;;
int DO =0;
for (i = 0; s1[i] != '\0'; i++)
{
for(j = 0; s2[j] != '\0'; j++)
{
if (s1[i] == s2[j])
{
DO = 1;
}
if(!DO)
{
s1[k++] = s1[i];
}
}
}
s1[j] = '\0';
}
int main()
{
char s1[] = "4567yuljf";
char c1[] = "ljf";
squeeze(s1,c1);
printf("%s",s1[1]);
}