剔除字符串中的特定字符和重复字符

#include <stdio.h>
void del_char(char *str, char ch)
{
        char *p1,*p2;
        p1=p2=str;
        while(*p2!=''){
                if(*p2!=ch)
                        p1++;
                p2++;
                *p1=*p2;
        }
}
void del_same(char *str)
{
        char *p1,*p2;
        p1=p2=str;
        while(*p2!=''){
                if(*(p2+1)!=*p1)
                        p1++;
                p2++;
                *p1=*p2;
        }
}

int main(int argc, char**argv)
{
        char *str=argv[1];
        printf("ORG:%sn",str);
        del_char(str,'a');
        printf("Del_a:%sn",str);
        del_same(str);
        printf("Del_same:%sn",str);

        return 0;
}