C89：声明大型const数组，然后使用它，然后初始化它

发布于 2025-01-28 11:19:43 字数 319 浏览 6 评论 0原文

这纯粹是为了可读性。我想拥有一个很大的恒定值，但这会使我的文件阅读愉快得多。因此，我想在使用后初始化该数组，尽管我希望它是恒定的。我知道这可能是不可能的，但这可能也很普遍。那么有哪些解决方法？我现在不想创建一个单独的文件。

像：

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

array_of_values = {0.123f, 0.456f, 0.789f ...};

原文

This is purely for readability. I want to have a very large constant array of values, but it makes my file a lot less pleasant to read. So I'd like to have that array initialized after use, though I want it to be constant. I know this is probably impossible, but it's probably also very common. So what workarounds are there ? I do not want to create a separate file right now.

Some thing like :

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

array_of_values = {0.123f, 0.456f, 0.789f ...};

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紫南 2025-02-04 11:19:43

首先，您要做的不是初始化，而是简单的分配。而且您无法分配到数组。而且您不能在功能之外具有一般性语句。如果要初始化数组，则在定义数组时需要执行。

话虽如此，您必须记住（或了解）没有明确初始化的任何定义为暂定。

这意味着您可以创建一个初步的定义，基本上是为了使声明摆脱困境。然后，在源文件中的稍后位置，您可以添加实际定义：

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

static const float array_of_values[] = { 0.123f, 0.456f, 0.789f, /* ... */ };

First of all what you're doing is not initialization, it's plain assignment. And you can't assign to an array. And you can't have general statements outside of functions. If you want to initialize the array, you need to do it when defining the array.

With that said, you have to remember (or learn) that any definition without explicit initialization is tentative.

That means you can create a tentative definition, basically to get the declaration out of the way. Then at a later place in the source file you can add the actual definition:

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

static const float array_of_values[] = { 0.123f, 0.456f, 0.789f, /* ... */ };

回复收藏 0 原文

长不大的小祸害 2025-02-04 11:19:43

这些是使文件不那么麻烦的常见解决方案：

static const float array_of_values[1000] = { MACRO }; // macro being an initalizer list

或者

static const float array_of_values[1000] = 
{ 
  #include "initlist.h"
};

我个人会推荐宏观版本，因为它更灵活且不太神秘。您仍然可以在单独的标头文件中声明宏。

还有一些暂定的定义通常是一个坏主意，因为它使该代码变得神秘且难以阅读：

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

static const float array_of_values[1000] = {0.123f, 0.456f, 0.789f};

#include <stdio.h>

int main (void)
{
  printf("%f\n", array_of_values[0]);
  printf("%f\n", getValueFromArray(0));
}

These are common solutions to make the file less cumbersome to read:

static const float array_of_values[1000] = { MACRO }; // macro being an initalizer list

static const float array_of_values[1000] = 
{ 
  #include "initlist.h"
};

I would personally recommend the macro version since it's more flexible and less mysterious. You could still declare the macro in a separate header file.

There's also tentative definitions which is generally a bad idea, again because it makes the code mysterious and hard to read:

static const float array_of_values[1000];

float getValueFromArray(int index)
{
    return array_of_values[index];
}

static const float array_of_values[1000] = {0.123f, 0.456f, 0.789f};

#include <stdio.h>

int main (void)
{
  printf("%f\n", array_of_values[0]);
  printf("%f\n", getValueFromArray(0));
}

回复收藏 0 原文

我家小可爱 2025-02-04 11:19:43

尝试以下操作：

#include <stdio.h>

static float array_of_values_base[1000]; // the effective array has "base" in its identifier
static const float *array_of_values = array_of_values_base; // your array is now a pointer

float getValueFromArray(int index)
{
    return array_of_values[index];
}

int main(void) {
    array_of_values_base[0] = 0.123f;
    array_of_values_base[1] = 0.456f;
    array_of_values_base[2] = 0.789f;
    // ...
    printf("value at index 1 is %f\n", getValueFromArray(1));
}

Try this:

#include <stdio.h>

static float array_of_values_base[1000]; // the effective array has "base" in its identifier
static const float *array_of_values = array_of_values_base; // your array is now a pointer

float getValueFromArray(int index)
{
    return array_of_values[index];
}

int main(void) {
    array_of_values_base[0] = 0.123f;
    array_of_values_base[1] = 0.456f;
    array_of_values_base[2] = 0.789f;
    // ...
    printf("value at index 1 is %f\n", getValueFromArray(1));
}

回复收藏 0 原文

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