程序代码：

#include <stdlib.h>
#include <stdio.h>

#define TRUE  1
#define FALSE 0

char *del_substr(char *str, char const *substr);

int main()
{
    char        str1[]= "123456789";
    char const  * str2= "345";
    printf("before delet:          %s\n", str1);
    printf("will delete the chars: %s\n", str2);
    del_substr(str1, str2);
    printf("After delete:          %s\n", str1);

    system("pause");
    return 0;

 }

char *del_substr(char *str, char const *substr)
{
    char const * subP;
    char *strP;
    char *temp;
    int  flag = TRUE;
    strP = str;

    if( (!*str) || *substr=='\0' )             //判断两个字符串是否有空字符串
       return FALSE;                           //(!*str)和*str=='\0'是等价的

    while(*strP)
    {
        temp = strP;
        subP = substr;
        for(; *subP; subP++)
        {
            if(*strP == *subP)
            {
                strP++;
                flag = FALSE;
                continue;
            }
            break;
        }

        if(*subP == '\0')
        {
            while(*temp++ = *strP++)
                ;
            break;
        }

        if(flag)
            strP++;
    }
    return TRUE;
}

程序代码：

#include <stdlib.h>
#include <stdio.h>

void reverse_string(char *str2);
int main()
{
    char   str1[]= "123456789";
    printf("before delet :          %s\n", str1);
    reverse_string(str1);

    system("pause");
    return 0;
}
void reverse_string(char *str2)
{
    char *rever;
    int   count;
    count=strlen(str2);
    printf("%d\n",count);
    for(;count>-1;count--)
        *rever++=*(count+str2);
    printf("%s\n",rever);
}

/home/zhangfeifei/文档/qt学习/明解c语言/print-6/main.c:298: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
     *p=a;
       ^

程序代码：

#include <stdio.h>
#include <string.h>
void reverse_string(char *str2);
int main()
{
    char   str1[]= "12345678";
    printf("before delet :          %s\n", str1);
    reverse_string(str1);
    system("pause");
    return 0;
}
void reverse_string(char *str2)
{
    char  *p;
    char   a[20];
    *p=a;
    int   count;
    count=strlen(str2);
    printf("%d\n",count);
    printf("最后一个字符：%c\n",*(str2+count-1));
    for(;count>-1;count--)
        *p++=*(count+str2-1);
    *p='\0';
    printf("%s\n",a);
}