Question

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <stdint.h>
#include <inttypes.h>

typedef struct tmp_num{
    int tmp_1;
    int tmp_2;
}t_num;

/* Dichiarazione prototipi secondo le direttive di pthread */
void *num_mezzo_1(void *num_orig);
void *num_mezzo_2(void *num_orig);

int main(int argc, char *argv[]){

    /* Inizializzo i 2 thread */
    pthread_t thread1, thread2;
    int tmp=0,rc1,rc2,num;

    t_num main_tnum;
    num=atoi(argv[1]);
    if(num <= 3){
        printf("Questo è un numero primo: %d\n", num);
        exit(0);
    }
    if( (rc1=pthread_create( &thread1, NULL, &num_mezzo_1, (void *)num)) ){
        printf("Creazione del thread fallita: %d\n", rc1);
        exit(1);
    }
    if( (rc2=pthread_create( &thread2, NULL, &num_mezzo_2, (void *)num)) ){
            printf("Creazione del thread fallita: %d\n", rc2);
            exit(1);
    }
    main_tnum.tmp_1 = 0;
    main_tnum.tmp_2 = 0;
    pthread_join(thread1, (void **)&(main_tnum.tmp_1));
    pthread_join(thread2, (void **)&(main_tnum.tmp_2));
    tmp=main_tnum.tmp_1+main_tnum.tmp_2;
    if(tmp>2){
        printf("Questo NON è un numero primo: %d\n", num);
    }
    else{
        printf("Questo è un numero primo: %d\n", num);
    }
    exit(0);
}

void *num_mezzo_1(void *num_orig){
    t_num p1_tnum;
    int cont_1;
    int n_orig=(int)num_orig;
    p1_tnum.tmp_1 = 0;
    for(cont_1=1; cont_1<=(n_orig/2); cont_1++){
        if((n_orig % cont_1) == 0){
            (p1_tnum.tmp_1)++;
        }
    }
    pthread_exit((void *)(p1_tnum.tmp_1));
    return NULL;
}

void *num_mezzo_2(void *num_orig){
    t_num p2_tnum;
    int cont_2;
    int n_orig=(int)num_orig;
    p2_tnum.tmp_2 = 0;
    for(cont_2=((n_orig/2)+1); cont_2<=n_orig; cont_2++){
        if((n_orig % cont_2) == 0){
            (p2_tnum.tmp_2)++;
        }
    }
    pthread_exit((void *)(p2_tnum.tmp_2));
    return NULL;
}

我正在使用Debian Sid 64bit，我对这个已开发的简单程序有疑问如果我使用clang -Wall -Wextra -o test prime.c -lpthread进行编译，我只有1个警告（未使用的argc ），程序运行正常。
但如果我使用GCC-4.7.2（gcc -Wall -Wextra -o test prime.c -lpthread）编译它，我会发出更多警告（未使用的argc +各种从指针转换为整数不同大小）程序因SegFault而失败我不明白为什么铿锵有效，而GCC却没有
修改

num_primo_pthread.c: In function ‘main’:
num_primo_pthread.c:33:57: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
num_primo_pthread.c:37:57: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
num_primo_pthread.c:16:14: warning: unused parameter ‘argc’ [-Wunused-parameter]
num_primo_pthread.c: In function ‘num_mezzo_1’:
num_primo_pthread.c:61:13: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
num_primo_pthread.c:68:15: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
num_primo_pthread.c: In function ‘num_mezzo_2’:
num_primo_pthread.c:75:13: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
num_primo_pthread.c:82:15: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

Answer 1

问题出在这一行

int n_orig=(int)num_orig;

num_orig是指向int的指针，而不是int。替换为：

int n_orig=(int)*num_orig;

编辑：

问题更深一点：

(void *)num

你不能这样做，指针不是那样用的，把它改成

(void *)&num

查看错误后进行第二次编辑：

你正在使用返回功能

(void *)(p2_tnum.tmp_2)

需要

(void *)(&p2_tnum.tmp_2)

这是一个局部变量，因此你无法返回它。

t_num p2_tnum

必须是分配了动态内存的指针。

t_num *p2_tnum = (t_num *) malloc(sizeof(t_num));

这些修补程序将要求您进行一些其他修改，但我认为您可以管理这些修改。

程序无法与GCC一起运行但与clang一起使用

1 个答案: