为什么我的 HelloWorld 函数没有在这个范围内声明?

2022-01-04 00:00:00 scope c++ 
#include <iostream>

using namespace std;

int main()
{
    HelloWorld();
    return 0;
}

void HelloWorld()
{
    cout << "Hello, World" << endl;
}

我在使用 g++ 时遇到以下编译错误:

I am getting the following compilation error with g++:

l1.cpp: In function 'int main()':
l1.cpp:5:15: error: 'HelloWorld' was not declared in this scope

推荐答案

您需要先声明或定义函数，然后才能使用它.否则，它不知道 HelloWorld() 作为函数存在.

You need to either declare or define the function before you can use it. Otherwise, it doesn't know that HelloWorld() exists as a function.

在你的主函数之前添加:

Add this before your main function:

void HelloWorld();

或者，您可以在 main() 之前移动 HelloWorld() 的定义:

Alternatively, you can move the definition of HelloWorld() before your main():

#include <iostream>
using namespace std;

void HelloWorld()
{
  cout << "Hello, World" << endl;
}

int main()
{
  HelloWorld();
  return 0;
}

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