新人求助，想用多线程完成文件读取，但是遇到了错误一直没办法解决

[猫鸠]

我想写一个用多线程来读取文件并且计算文件中的单词词频的程序。但是我一直得到No matching function for call to 'pthread_create'这个错误，上网搜索了很久也没办法解决。

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <pthread.h>
#include <string.h>
#include <map>

using namespace std;

#define NUM_THREADS     5

void *countWordFrequency(void *str[100])
{
    //将void类型转换成string类型
    string s = (string)(char *)str;

    int count = 0, c = 0, i, j = 0, k, space = 0;
    char p[50][100], ptr1[50][100];

    for (i = 0;i< s.length();i++)
    {
        if ((s[i] == ' ')||(s[i] == ',')||(s[i] == '.'))
        {
            space++;
        }
    }
    for (i = 0, j = 0, k = 0;j < s.length();j++)
    {
        if ((s[j] == ' ')||(s[j] == 44)||(s[j] == 46))
        {
            p[i][k] = '\0';//把正在录入的设置成空格
            i++;
            k = 0;
        }
        else
            p[i][k++] = s[j]; //str[j] probably is the array which store the words
        //that are input into this vessel
        //i probably the number of the paticular word
        //j 是为了确认这个循环不超过单词的d总数量
    }
    k = 0; //
    for (i = 0;i <= space;i++)
    {
        for (j = 0;j <= space;j++)
        {
            if (i == j)
            {
                strcpy(ptr1[k], p[i]);//ptr1[k] is the pointer to the destination
                //array that the content is be copied.
                //p[i] is the string to be copied.
                //这个复制是复制一整个词而不是一个字母
                k++;
                count++;//i think the count is the number of the frequency words
                break;
            }
            else
            {
                if (strcmp(ptr1[j], p[i]) != 0)//strcmp is the comparing function
                    //! = 0 means that they are paired
                    //successively
                    continue;//then continue means that if it satify the
                //requirements then skip these sentence, restart the
                //sentence from the beginning.
                //so this continue means if ptr1 == p then step out
                //this circle and restart
                else
                    break;
            }
        }
    }
    for (i = 0;i < count;i++)
    {
        for (j = 0;j <= space;j++)
        {
            if (strcmp(ptr1[i], p[j]) == 0)
                c++;
        }
        printf("%s -> %d times\n", ptr1[i], c);//ptr1[i] is the place to store the
        //words of this code
        c = 0;
    }

    pthread_exit(NULL);

    return 0;
}

string readByLine()
{
    char buffer[256];
    fstream outFile;
    outFile.open("book.txt",ios::in);

    while(!outFile.eof())
    {
        outFile.getline(buffer,256,'\n');//getline(char *,int,char) 表示该行字符达到256个或遇到换行就结束
        cout<<buffer<<endl;
    }
    outFile.close();
    
    return 0;
}

int main ()
{
    pthread_t threads[NUM_THREADS];
    int indexes[NUM_THREADS];
    int rc;
    int i;
    
    //read file
    string r = readByLine();

    for( i=0; i < NUM_THREADS; i++ ){
        indexes[i] = i; //先保存i的值
        // 传入的时候必须强制转换为void* 类型，即无类型指针
        rc = pthread_create(&threads[i], NULL,
                            *countWordFrequency, (void *)&i);
        if (rc){
            cout << "Error: can create threads," << rc << endl;
            exit(-1);
        }
    }
    pthread_exit(NULL);
}

我遇到的错误是在117行，No matching function for call to 'pthread_create'。我试了很久都没办法解决，求助！

[WNs_ACE]

Xcode一样是需要添加-lpthread选项，我没有记错的话，xcode好像也是用gun的编译工具来的，你去查一下如何添加多线程设置就找到答案了

[WNs_ACE]

应该是需要添加-lpthread选项吧，你这个应该是gcc的编译器来的吧，你查一下如何添加多线程选项吧

[猫鸠]

引用 1 楼 WNs_ACE 的回复:

应该是需要添加-lpthread选项吧，你这个应该是gcc的编译器来的吧，你查一下如何添加多线程选项吧

我用的是Xcode

[smwhotjay]

链接问题。 -lpthread