Question

我目前是初学者，学习如何在C中使用pthread。我的代码目前运行，所以没有实际的错误，但它不是它应该做的。代码应提示用户输入每个问题，然后在用户输入信息后打印所有结果，但代码似乎在输入名称后跳过并完成。有人可以帮我找到我的代码出错的地方吗？下面是我的代码和运行时的输出：

#include <stdio.h
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>
#include <sched.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <string.h>
#include <pthread.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

typedef struct compound {
     char name [1024];
     int age;
     int birthMonth;
     int birthYear;
     int threadNumber;
}compound;

   void * threadName (void * param){

    compound *lparam = (compound *) param;

    int lock;

    lock = pthread_mutex_lock(&mutex);

    printf ("> Please type your name for thread %d\n", lparam->threadNumber);
    scanf ("%c", lparam->name);

    lock = pthread_mutex_unlock(&mutex);

    lock = pthread_mutex_lock(&mutex);

    printf ("> Please type your age for thread %d\n", lparam->threadNumber);
    scanf ("%d", &(lparam->age));

    lock = pthread_mutex_unlock(&mutex);

    lock = pthread_mutex_lock(&mutex);

    printf ("> Please type your birth month for thread %d\n", lparam->threadNumber);
    scanf ("%d", &(lparam->birthMonth));

    lock = pthread_mutex_unlock(&mutex);

    lock = pthread_mutex_lock(&mutex);

    printf ("> Please type your birth year for thread %d\n", lparam->threadNumber);
    scanf ("%d", &(lparam->birthYear));

    lock = pthread_mutex_unlock(&mutex);
    return NULL;
}

// main function
int main ( void) {

    pthread_t thread_ID3, thread_ID4;
    void *exitstatus;

    compound first, second;
    first.threadNumber= 1;
    second.threadNumber = 2;

    pthread_create (&thread_ID3, NULL, threadName, &first);
    pthread_create (&thread_ID4, NULL, threadName, &second);

    pthread_join (thread_ID3, &exitstatus);
    pthread_join (thread_ID4, &exitstatus);

    printf("Finished\n");

    getchar();
    return 0;
}

This is what happens when the code is executed:

[370user14@nostromo ex2]$ make
gcc -Wall  -c base_code.c
gcc -lm -lpthread base_code.o  -o baseprog
rm -f *.o *~
[370user14@nostromo ex2]$ ./baseprog 
> Please type your name for thread 1
gurinder
> Please type your age for thread 1
> Please type your birth month for thread 1
> Please type your name for thread 2
> Please type your age for thread 2
> Please type your birth month for thread 2
> Please type your birth year for thread 2
> Please type your birth year for thread 1
Finished

Answer 1

这里是更正后的代码，修复了scanf（），删除了杂乱，包含了适当的错误检查，每行只有一个语句每个语句只有一个语句，并且（最多）每个语句有一个变量声明随后和其他意见合并。

#include <stdio.h>
#include <stdlib.h> // exit(), EXIT_FAILURE
#include <pthread.h> // pthread_*()
//#include <semaphore.h>
//#include <sched.h>
//#include <unistd.h>
//#include <signal.h>
//#include <sys/types.h>
//#include <string.h>


pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

typedef struct compound
{
     char name [1024];
     int age;
     int birthMonth;
     int birthYear;
     int threadNumber;
} compound;


void * threadName (void * param)
{
    compound *lparam = (compound *) param;

    pthread_mutex_lock(&mutex);

    printf ("> Please type your name for thread %d\n", lparam->threadNumber);
    scanf ("%1023s", lparam->name);

    pthread_mutex_unlock(&mutex);

    pthread_mutex_lock(&mutex);

    printf ("> Please type your age for thread %d\n", lparam->threadNumber);
    scanf ("%d", &(lparam->age));

    pthread_mutex_unlock(&mutex);

    pthread_mutex_lock(&mutex);

    printf ("> Please type the number of your birth month for thread %d (January=1)\n", lparam->threadNumber);
    scanf ("%d", &(lparam->birthMonth));

    pthread_mutex_unlock(&mutex);

    pthread_mutex_lock(&mutex);

    printf ("> Please type your birth year for thread %d\n", lparam->threadNumber);
    scanf ("%d", &(lparam->birthYear));

    pthread_mutex_unlock(&mutex);
    pthread_exit( NULL );
} // end function: threadName


// main function
int main (void)
{

    pthread_t thread_ID3;
    pthread_t thread_ID4;


    compound first;
    compound second;

    first.threadNumber= 1;
    second.threadNumber = 2;

    if( 0 != pthread_create (&thread_ID3, NULL, threadName, (void*)&first) )
    { // then pthread_create failed
        perror( "pthread_create for first thread failed");
        exit( EXIT_FAILURE );
    }

    // implied else pthread_create successful

    if( 0 != pthread_create (&thread_ID4, NULL, threadName, (void*)&second) )
    { // then pthread_create failed
        perror( "pthread_create for second thread failed" );
        exit( EXIT_FAILURE );
    }

    // implied else pthread_create successful

    pthread_join (thread_ID3, NULL);
    pthread_join (thread_ID4, NULL);

    printf("Finished\n");

    int ch;
    while( (ch = getchar()) != EOF && '\n' != ch );
    getchar(); // wait for user to enter a final keystroke
    return 0;
} // end function: main

如何修复我使用pthread代码获得的此错误？

1 个答案: