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二维数组值

发布于 2024-10-16 21:58:58 字数 836 浏览 10 评论 0 原文

我想声明一个二维数组并为其赋值，而不运行 for 循环。

我想我可以使用以下想法，

int array[5] = {1,2,3,4,5};

它也可以很好地初始化二维数组。但显然我的编译器不喜欢这样。

/*
 1   8  12  20  25
 5   9  13  24  26
*/

#include <iostream.h>

int main()
{
    int arr[2][5] = {0};   // This actually initializes everything to 0.
    arr [1] [] = {1,8,12,20,25}; // Line 11
    arr [2] [] = {5,9,13,24,26};
    return 0;
}

J:\CPP\Grid>bcc32.exe Grid.cpp

用于 Win32 的 Borland C++ 5.5.1 版权所有 (c) 1993, 2000 Borland

网格.cpp：

错误 E2188 Grid.cpp 11：函数 main() 中的表达式语法

错误 E2188 Grid.cpp 12：函数 main() 中的表达式语法

警告 W8004 Grid.cpp 14：“arr”被分配了一个从未在 funct 中使用的值离子主()

* 编译中有 2 个错误 *

请帮助了解使用我的值集初始化 2d 数组的正确方法。

原文

I wanted to declare a 2D array and assign values to it, without running a for loop.

I thought I could used the following idea

int array[5] = {1,2,3,4,5};

Which works fine to initialize the 2D array as well. But apparently my compiler doesn't like this.

/*
 1   8  12  20  25
 5   9  13  24  26
*/

#include <iostream.h>

int main()
{
    int arr[2][5] = {0};   // This actually initializes everything to 0.
    arr [1] [] = {1,8,12,20,25}; // Line 11
    arr [2] [] = {5,9,13,24,26};
    return 0;
}

J:\CPP\Grid>bcc32.exe Grid.cpp

Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland

Grid.cpp:

Error E2188 Grid.cpp 11: Expression syntax in function main()

Error E2188 Grid.cpp 12: Expression syntax in function main()

Warning W8004 Grid.cpp 14: 'arr' is assigned a value that is never used in funct
ion main()

* 2 errors in Compile *

Please help as to what is the right way to initialize the 2d array with my set of values.

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眼泪淡了忧伤 2024-10-23 21:58:58

像这样：

int main()
{
    int arr[2][5] =
    {
        {1,8,12,20,25},
        {5,9,13,24,26}
    };
}

这应该包含在你的 C++ 教科书中：你使用的是哪一本？

不管怎样，最好考虑使用 std::vector 或一些现成的矩阵类，例如来自 Boost 的矩阵类。

Like this:

int main()
{
    int arr[2][5] =
    {
        {1,8,12,20,25},
        {5,9,13,24,26}
    };
}

This should be covered by your C++ textbook: which one are you using?

Anyway, better, consider using std::vector or some ready-made matrix class e.g. from Boost.

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日暮斜阳 2024-10-23 21:58:58

在 C 或 C++ 中初始化多维数组的正确方法是

int arr[2][5] = {{1,8,12,20,25}, {5,9,13,24,26}};

如果需要，您可以使用相同的技巧来初始化更高维的数组。

另外，在初始代码中要小心 - 您试图在数组中使用 1 索引偏移量来初始化它。这没有编译，但如果编译了，就会导致问题，因为 C 数组是 0 索引的！

The proper way to initialize a multidimensional array in C or C++ is

int arr[2][5] = {{1,8,12,20,25}, {5,9,13,24,26}};

You can use this same trick to initialize even higher-dimensional arrays if you want.

Also, be careful in your initial code - you were trying to use 1-indexed offsets into the array to initialize it. This didn't compile, but if it did it would cause problems because C arrays are 0-indexed!

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后来的我们 2024-10-23 21:58:58

只是想指出您不需要指定数组的所有维度。

最左边的维度可以由编译器“猜测”。

#include <stdio.h>
int main(void) {
  int arr[][5] = {{1,2,3,4,5}, {5,6,7,8,9}, {6,5,4,3,2}};
  printf("sizeof arr is %d bytes\n", (int)sizeof arr);
  printf("number of elements: %d\n", (int)(sizeof arr/sizeof arr[0]));
  return 0;
}

Just want to point out you do not need to specify all dimensions of the array.

The leftmost dimension can be 'guessed' by the compiler.

#include <stdio.h>
int main(void) {
  int arr[][5] = {{1,2,3,4,5}, {5,6,7,8,9}, {6,5,4,3,2}};
  printf("sizeof arr is %d bytes\n", (int)sizeof arr);
  printf("number of elements: %d\n", (int)(sizeof arr/sizeof arr[0]));
  return 0;
}

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