char *strrpc(char *str,char *oldstr,char *newstr)
{
     int i = 0;
     char bstr[strlen(str)];//转换缓冲区
     memset(bstr,0,sizeof(bstr));
     for(i = 0; i < strlen(str); i++)
     {
        if(!strncmp(str+i,oldstr,strlen(oldstr)))
        {//查找目标字符串
            strcat(bstr,newstr);
            i += strlen(oldstr) - 1;
        }else
        {
            strncat(bstr,str + i,1);//保存一字节进缓冲区

        }
     }
     strcpy(str,bstr);
     return str;
}

dstName = strrpc(srcName, "/sdb/data/","/mnt/usb33/download/");   将字符串srcName中的/sdb/data/替换成后者