从虚空*转换为char **用C [英] Converting from void* to char ** in C

问题描述

我有铸造，我传递给线程处理器function.I我不能强制转换乌塞林返回字符串array.Suggestions请在字符串数组中重类问题

 静态字符*命令;
无效* thread_handler1（无效*乌塞林）
{
        字符文件名1 [20] =（字符*）乌塞林;
看跌期权（内螺纹）;
        的printf（％U（INT）乌塞林）;
        //的printf（％U，文件名1）;
        如果（STRCMP（指挥，监控）== 0）
        {
                 dms_monitor（文件名）;
                 的printf（％S，文件名1）;
        }
}无效transact_client（INT袜子）
{
        INT I;
        焦炭recvbuffer [MAX_BUFFER_SIZE]
        字符分隔符[] =;
        字符*结果= NULL;
        字符*文件名[10];
        INT rdcount = 0;
        INT索引= 0;
        //结构文件的用户文件[20];
       //字符*命令;
        PID的pthread_t;
        如果（（rdcount =的recv（袜子，recvbuffer，sizeof的（recvbuffer），0））==  -  1）
                PERROR（问题与文件描述符）;
        结果=的strtok（recvbuffer，分隔符）;
        命令=结果;
        的printf（命令为％s \\ n，文件名[0]）;
        而（结果！= NULL）
        {
              //输出（结果是\\％s \\的\\ n，文件名[指数]）;
               结果=的strtok（NULL，分隔符）;
               文件名[++指数] =结果;
               的printf（结果是\\％s \\的\\ n，文件名[索引1]）;
        }        的printf（％U，文件名）;
        在pthread_create（安培; PID，NULL，thread_handler1，＆安培;文件名）;
        pthread_detach（pthread_self（））;
 

解决方案

现在的问题是这一行：

 字符文件名1 [20] =（字符*）乌塞林;
 

右侧是一个char *和左侧字符的阵列。
如果乌塞林指向一个字符串，没有必要去尝试为它分配新的空间。

试试这个：

 的char *文件名1 =（字符*）乌塞林;
 

编辑：

有在 transact_client 以及一些错误。

文件名被声明为指针数组。真的是你想要的吗？

文件名[0] 从未赋值。

＆安培;文件名（这是字符*** ）发送给需要一个char功能*。

I am having problem in re type casting the string array which I passed to the thread handler function.I am not able to typecast userIn back to string array.Suggestions please.

static char *command;
void *thread_handler1 (void *userIn)
{
        char filename1[20]= (char *)userIn;
puts("inside thread");
        printf("%u",(int)userIn);


        //printf("%u",filename1);
        if(strcmp(command,"monitor")==0)
        {
                 dms_monitor(filename1);
                 printf("%s",filename1);
        }
}

void transact_client(int sock)
{
        int i;
        char recvbuffer[MAX_BUFFER_SIZE];
        char delimiter[]=" ";
        char *result=NULL;
        char *filename[10];
        int rdcount=0;
        int index=0;
        //struct file userFile[20];
       // char *command;
        pthread_t pid;


        if((rdcount=recv(sock,recvbuffer,sizeof(recvbuffer),0))==-1)
                perror("Problem with file descriptor");


        result=strtok(recvbuffer,delimiter);
        command=result;
        printf("the command is %s\n",filename[0]);
        while(result != NULL)
        {
              // printf("result is \"%s\"\n",filename[index]);
               result=strtok(NULL,delimiter);
               filename[++index]=result;
               printf( "result is \"%s\"\n", filename[index-1]);
        }

        printf("%u",filename);
        pthread_create(&pid,NULL,thread_handler1,&filename);
        pthread_detach(pthread_self());

解决方案

The problem is with this line:

    char filename1[20]= (char *)userIn;

The right side is a char* and the left side an array of char. If userIn points to a string, there is no need to try to allocate new space for it.

Try this instead:

    char *filename1 = (char *)userIn;

Edit:

There are a number of bugs in transact_client as well.

filename is declared as an array of pointers. Is that really what you want?

filename[0] is never assigned a value.

&filename (which is a char***) is sent to a function that expects a char*.

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