将二维数组复制到另一个

Question

我正在从“C Primer Plus”一书中学习 C 编程语言。我正在解决一个练习，但我撞墙了:

Write a program that initializes a two-dimensional 3×5 array-of- double and uses a VLA-based function to copy it to a second two-dimensional array. Also provide a VLA-based function to display the contents of the two arrays. The two functions should be capable,in general, of processing arbitrary N×M arrays. (If you don’t have access to a VLA-capable compiler, use the traditional C approach of functions that can process an N×5 array).

我不能使用 VLA，因为我的编译器不支持它，我使用 VC2013。这是我的代码:

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif
#include <stdio.h>

#define LIM1 10
#define LIM2 10
#define LIM3 2
int ct, ct2, size;

void copy_arr(double *[LIM3], double *[LIM3], int size, int lim);
int main(void)
{
    double arr1[LIM1][LIM2], arr2[LIM1][LIM2];

    printf("Enter the size of the array\n");
    scanf("%d", &size);
    printf("Enter the array elements\n");

    for (ct = 0; ct < size; ct++)
    {
         for (ct2 = 0; ct2 < LIM3; ct2++)
         {
             scanf("%lf", &arr1[ct][ct2]);
         }
    }
    printf("\n");

    for (ct = 0; ct < size; ct++)
    {
        for (ct2 = 0; ct2 < LIM3; ct2++)
        {
            printf("%.2f ", arr1[ct][ct2]);
        }
        printf("\n");
    }
    printf("\n");

    copy_arr(arr1, arr2, size, LIM3);

    for (ct = 0; ct < size; ++ct)
    {
        for (ct2 = 0; ct2 < LIM3; ++ct2);
        {
            arr2[ct][ct2] = arr1[ct][ct2];
            printf("%.2f ", arr2[ct][ct2]);
        }
        printf("\n");
    }
    printf("\n"); 

    system("pause");

}

void copy_arr(double (*arr1)[LIM3], double (*arr2)[LIM3], int size, int lim)
{
     for (ct = 0; ct < size; ct++)
     {
         for (ct2 = 0; ct2 < lim; ct2++)
         {
             arr2[ct][ct2] = arr1[ct][ct2];
         }
     }

return;
}

输出:http://postimg.org/image/mnswuyy2b/

我不知道如何将 size 变量的值传递给函数 copy_arr。除了VLA还有其他方式吗？

Answer 1

arr1[LIM1][LIM2] 是一个大小为 LIM1 的数组，由大小为 LIM2 的数组组成。因此copy_arr的签名应该是:

void copy_arr(double arr1[LIM1][LIM2], double arr2[LIM1][LIM2], int size, int lim);

或者因为 C++ 允许省略第一维:

void copy_arr(double arr1[][LIM2], double arr2[][LIM2], int size, int lim);

或者，由于数组到指针的转换，数组可以转换为指向大小为 LIM2 的数组的指针:

void copy_arr(double (*arr1)[LIM2], double (*arr2)[LIM2], int size, int lim);

您的代码中还有另一个问题:

    for (ct2 = 0; ct2 < LIM3; ++ct2);

最后一个分号使以下 {} block 不属于循环。将其删除。

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