使用Struct将String数组和索引传递给C中的线程

Posted 2021-04-08

我试图传递一个字符串数组和索引从哪里开始结束搜索数组，我无法解决它在过去两天。我发送给pthread_create一个struct data thread_data，这里我能够发送int和long数据，但不能发送字符串数组，有人可以帮助我，如何传递这些。

struct data{
        int  tid;
        unsigned long start;
        unsigned long end;
        char * word;
        char * str;
        };

struct data thread_data[NUM_THREADS];
void *searchString(void *passeddata)
{
   struct data *t_data;
   int tid1;
   char * str[3];
   t_data=(struct data *) passeddata;
   tid1=t_data->tid;
   str=t_data->str;
  .....
   pthread_exit(NULL);
}       
int main(int argc, char *argv[])
{
...
char  work[]={"First Line","Second line","Third line"};
...

   while(fgets(arr[index],120, fp)!=NULL){
        index=index+1;
        thread_data[index].tid=index;
        thread_data[index].str=work;
        ...
        rc=pthread_create(&threads[index],NULL,searchString,(void *)&thread_data[index]);
...     
        }

   pthread_exit(NULL);
}

答案

要保存多个字符串，您需要2D数组。

const char  *work[]={"First Line","Second line","Third line", "Fourth Line"};

你需要在struct data中使用指向指针来保存上面的数组。

struct data{
        .....
        const char **str;
        size_t lenOfStr;
        };

并将数组的长度显式传递给main函数的线程函数。

您的示例代码可能如下所示。

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
struct data{
        int  tid;
        unsigned long start;
        unsigned long end;
        char * word;
        const char **str;
        size_t lenOfStr;
        };

struct data thread_data[3];

void *searchString(void *passeddata)
{
   struct data *t_data;
   int tid1;
   const char **str = NULL;
   t_data=(struct data *) passeddata;

   tid1=t_data->tid;
   str=t_data->str;

  int i = 0;
   for (i = 0;i<t_data->lenOfStr;i++)
   printf("%s
", str[i]);

   pthread_exit(NULL);
}

int main(int argc, char *argv[])
{
        const char  *work[]={"First Line","Second line","Third line", "Fourth Line"};
        int index = 0;
        pthread_t threadid=0;

        thread_data[index].tid=index;
        thread_data[index].str=work;
        thread_data[index].lenOfStr = sizeof(work)/sizeof(*work); // Calculate the size of work here

        int rc=pthread_create(&threadid,NULL,searchString,&thread_data[index]);

        pthread_exit(NULL);
}