矢量保持在列印輸出

#include <iostream>
#include <stdlib.h>
#include <pthread.h>
#include <fstream>
#include <sstream>
#include <mutex>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <vector>

using namespace std;

#define NUM_THREADS 2
pthread_mutex_t mutexChild;
pthread_cond_t condChild;

vector<int> vect;

void openfile(ifstream&, string);

void* childthread(void *args)
{
    
    ifstream inFile;
    openfile(inFile, "Fruits.txt");
    
    string line;
    pthread_mutex_lock(&mutexChild);
    int countt = 0;
    int lines = 0;
    int total = 0;
    
    while (!inFile.eof())
    {
        
        getline(inFile, line);
        
        countt = 0;
        
        for (int i = 0; i < line.size(); i  )
            if ((line[i] >= 'A' && line[i] <= 'Z')
                    || (line[i] >= 'a' && line[i] <= 'z'))
            {
                
                countt  ;
            }
        
        lines  ;
        vect.push_back(countt);
    }
    
    pthread_mutex_unlock(&mutexChild);
    
    pthread_exit(NULL);
}

void* parentthread(void *args)
{
    
    ifstream inFile;
    openfile(inFile, "Fruits.txt");
    string line;
    
    pthread_mutex_lock(&mutexChild);
    
    int lines = 0;
    int total = 0;
    
    int countt = 0;
    while (!inFile.eof())
    {
        
        getline(inFile, line);
        
        for (int i = 0; i < vect.size(); i  )
            cout << vect[i] << endl;
    }
    
    pthread_exit(NULL);
}

int main(int argc, char *argv[])
{
    
    pthread_t threads;
    int thrd1;
    //int i;
    int thrd2;
    
    pthread_mutex_init(&mutexChild, NULL);
    
    thrd1 = pthread_create(&threads, NULL, childthread, NULL);
    
    if (thrd1)
    {
        cout << "Error:unable to create thread," << thrd1 << endl;
        exit(-1);
    }
    
    pthread_t threads2;
    
    thrd2 = pthread_create(&threads2, NULL, parentthread, NULL);
    
    if (thrd2)
    {
        cout << "Error:unable to create thread," << thrd2 << endl;
        exit(-1);
    }
    
// pthread_join(threads,NULL);
// pthread_join(threads2, NULL);
//threads.join();
///threads2.join();
    
    pthread_mutex_destroy(&mutexChild);
    pthread_cond_destroy(&condChild);
    
    pthread_exit(NULL);
}

void openfile(ifstream &inFile, string fname)
{
    
    inFile.open(fname);
    if (inFile.is_open())
    {
        
        // cout << "Successfully opened File" << endl;
    }
}

當我只需要列印一次時，我的子執行緒會繼續列印輸出 8 次。我的 txt 檔案中有 8 行，所以我猜這就是它列印輸出 8 次的原因。誰能告訴我它為什么會這樣以及我如何改變它。我也知道為什么要執行此任務更簡單，但我需要使用 posix 執行緒交換資料。它的列印像這樣 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 8 次我只需要 1 2 3 4 5 6 7 8

uj5u.com熱心網友回復：

    while (!inFile.eof())
    {
        
        getline(inFile, line);
        
        for (int i = 0; i < vect.size(); i  )
            cout << vect[i] << endl;
    }

為檔案中的每一行列印vector一次內置子執行緒的內容（有點。請參閱Why is iostream::eof inside a loop condition (ie `while (!stream.eof())`）被認為是錯誤的？）。這不是你想要的。似乎不需要在這里閱讀檔案。子執行緒已經讀取了檔案并完成了所有的vector組裝作業。

解決眼前的問題，重復列印資料，您所需要的只是

    for (int i = 0; i < vect.size(); i  )
        cout << vect[i] << endl;

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