从a中删除b中已有的元素
#include<stdio.h>
int main()
{char a[30],b[30],*p,*q;printf("please enter a string:\n");scanf("%s",a);printf("a is:%s",a);printf("\n"); printf("please enter b string:\n");scanf("%s",b);printf("b is:%s",b);printf("\n"); p=a;q=b;int i,j;int k=0;for(i=0;*(p+i)!='\0';i++){for(j=0;*(q+j)!='\0'&&*(q+j)!=*(p+i);j++);if(*(q+j)=='\0') {*(p+k)=*(p+i);k++;}} for(i=0;i<k;i++){printf("%c",*(p+i));}
}