c - c 中的动态内存分配会引发特定大小的错误

Question

我正在尝试(动态地)创建一个数组并用随机数填充它。

我在 Linux 上。程序编译没有错误。这是 C 代码:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void create_array(int **, int);
void populate_array(int *X, int size, int low, int high);
void display_array(int *X, int size);


int main()
{
    int *A = NULL;
    int size = 7;
    int low = 10;
    int high = 1000;
    create_array(&A, size);
    populate_array(A, size, low, high);
    display_array(A, size);
    return 0;
}

void create_array(int **X, int size)
{
    *X = (int *)(malloc(size));
}

void populate_array(int *X, int size, int low, int high)
{
    srand(time(0));
    for (int i = 0; i < size; ++i)
    {
        *(X + i) = low + rand() % (high + 1 - low);
    }
}

void display_array(int *X, int size)
{
    for (int i = 0; i < size; ++i)
    {
        if (i % 10 == 0)
            printf("\n");
        printf("%d\t", *(X + i));
    }
    printf("\n");
}

但是，当我运行它时，出现以下错误:

malloc.c:2394: sysmalloc: 断言`(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize - 1)) == 0)' 失败。 中止(核心转储)

此错误仅在 size = 7 时产生。对于较低的值，一切都很好。但是对于更高的值，那就是另一回事了! size = 20 的输出:

455     526     335     719     907     695     1041    0       154481972       154546741
154481459       154743095       154482992       875836721       960049720       926419250       909326389       154219063       808465977       842479924

相比之下，C++ 中的相同程序(几乎)给出了预期的输出。这是代码:

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

void create_array(int *&, int);
void populate_array(int *X, int size, int low, int high);
void display_array(int *X, int size);

int main()
{
    int *A;
    int size = 100;
    int low = 10;
    int high = 1000;
    create_array(A, size);
    populate_array(A, size, low, high);
    display_array(A, size);
    return 0;
}

void create_array(int *&X, int size)
{
    X = new int[size];
}

void populate_array(int *X, int size, int low, int high)
{
    srand(time(0));
    for (int i = 0; i < size; ++i)
    {
        X[i] = low + rand() % (high + 1 - low);
    }
}

void display_array(int *X, int size)
{
    for (int i = 0; i < size; ++i)
    {
        if (i % 10 == 0)
            cout << endl;
        cout << X[i] << "\t";
    }
    cout << endl;
}

我做错了什么？

Answer 1

*X = (int *)(malloc(size));

您正在分配 size 字节数，也许您想要的是

*X = malloc(sizeof(int)*size);

Note: malloc takes number of bytes to be allocated as argument. Also for for c implementation you might want to read Why not to cast malloc return.