“ Y不命名类型” C ++中的错误 [英] "Y does not name a type" error in C++

问题描述

我不知道要搜索什么来找到对此的解释，所以我要问。

我有此代码报告了错误：

 结构设置{
 int width; 
 int高度； 
}设置； 
 
 settings.width = 800; //设置未将类型错误命名为
 settings.height = 600; //设置未将类型错误命名为
 
 int main（）{
 cout<< settings.width<< << settings.height<<恩德尔
  

但是如果我将值赋值放在main中，它将起作用：

 结构设置{
 int width; 
 int高度； 
}设置； 
 
 main（）{
 settings.width = 800; //没有错误
 settings.height = 600; //没有错误
  

你能解释一下为什么吗？

编辑：

关于Ralph Tandetzky的回答，这是我的完整结构代码。您能告诉我如何分配代码段结构吗？

 结构设置{
结构尺寸{
 int width; 
 int高度； 
}屏幕； 
 
结构Build_menu：Dimensions {
 int border_width; 
} build_menu; 
}设置； 
  

解决方案

您不能将赋值放在函数的上下文之外C ++。如果您对有时看到 = 符号在函数上下文之外使用感到困惑，例如：

  int x = 42; //< ==这不是一项任务！ 
 
 int main（）
 {
 // ... 
} 
  

这是因为 = 符号也可以用于初始化。在您的示例中，您没有初始化数据成员 width 和 height ，而是为它们分配了一个值。 / p>

I don't know what to search to find an explanation for this, so I am asking.
I have this code which reports error:

struct Settings{
    int width;
    int height;
} settings;

settings.width = 800; // 'settings' does not name a type error
settings.height = 600; // 'settings' does not name a type error

int main(){
    cout << settings.width << " " << settings.height << endl;

but if I put the value assignment in main, it works:

struct Settings{
    int width;
    int height;
} settings;

main () {
    settings.width = 800; // no error
    settings.height = 600; // no error

Can you explain me why?

EDIT:
Regarding to Ralph Tandetzky's answer, here is my full struct code. Could you show me how to assign the values as you did with my snippet struct?

struct Settings{
    struct Dimensions{
        int width;
        int height;
    } screen;

    struct Build_menu:Dimensions{
        int border_width;
    } build_menu;
} settings;

解决方案

You cannot put assignments outside the context of a function in C++. If you're puzzled by the fact that you sometimes saw the = symbol being used outside the context of a function, such as:

int x = 42; // <== THIS IS NOT AN ASSIGNMENT!

int main()
{
    // ...
}

That's because the = symbol can be used for initialization as well. In your example, you are not initializing the data members width and height, you are assigning a value to them.

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