[错误]期望在数字常量之前的nonqualified-id [英] [Error] expected unqualified-id before numeric constant

问题描述

我的代码在这里：

my code is here:

#include<iostream>
using namespace std;

#define MAX 100
#define NEWLINE '\n'
#define MIN 0

int main()
{
	const int MAX = 100;
	const float PI = 3.1415;
	const char BELL = '\a';
	cout << "MAX = " << MAX << NEWLINE;
	cout << "\nBELL" << BELL;
	float ds = PI*3*3;
	cout << "\nDien tich hinh tron ban kinh 3 la: " << ds << NEWLINE;
	return 0;
}

当我编译它时说

4 13 C：\ Users \Administrator \Desktop \Tai lieu hoc lam game\c ++ \ Untitled5.cpp [错误]预期不合格的数字常数之前



我尝试了什么：



我不知道如何修复它。

when i compile it said
4 13 C:\Users\Administrator\Desktop\Tai lieu hoc lam game\c++\Untitled5.cpp [Error] expected unqualified-id before numeric constant

What I have tried:

I don't know how to fix it.

推荐答案

#define MAX 100
#define NEWLINE '\n'
#define MIN 0

int main()
{
// You have defined MAX as 100 above so the following line evaluates to:
// const int 100 = 100; which is not valid
const int MAX = 100;

为什么你定义了 NEWLINE ？你应该使用 ios 常量 endl 来使用 cout 。

Also why have you defined NEWLINE? You should use the ios constant endl to complete a line using cout.

Quote：

#define MAX 100

#define MAX 100

Quote：

const int MAX = 100;

const int MAX = 100;

您正在重新定义 MAX 符号。你必须丢弃这两个定义中的一个。





请注意，在 C ++ ，你的常量并不需要 #define ：你最好使用 const ，甚至更好， constexpr 。

You are re-defining the MAX symbol. You must discard one of the two definitions.


Please note, in C++, you don't really need the #define for your constants: you'd better use const or, even better, constexpr.

您已将 MAX 定义为100.所以line

You have defined MAX as 100. So the line

const int MAX = 100;

将转换为

will be converted to

const int 100 = 100;

这是一个无效的语句并导致看到错误消息。



解决方案：

删除行或定义 MAX 的行。

which is an invalid statement and results in the seen error message.

Solution:
Remove that line or the line defining MAX.

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