c++ - 额外的反斜杠字符不会影响我的程序。为什么？

Question

这段代码可以在 g++ 上正常运行。我不是没有为什么。它应该给出一个错误。

#include <iostream>
using namespace std;
int main(){
    int x=9;
    int y=6;
    //note that there is extra backslash in the end of if statement
    if(x==y)\
    {
        cout<<"x=y"<<endl;
    }
    //note that there is extra backslash in the end of if statement
    if(x!=y)\
    {
        cout<<"x!=y"<<endl;
    }
    return 0;
}

Answer 1

来自 C++ 标准:

(C++11, 2.2p1) "Each instance of a backslash character (\) immediately followed by a new-line character is deleted, splicing physical source lines to form logical source lines. Only the last backslash on any physical source line shall be eligible for being part of such a splice."

C 说的完全一样:

(C11, 5.1.1.2 Translatation phases p1) "Each instance of a backslash character (\) immediately followed by a new-line character is deleted, splicing physical source lines to form logical source lines."

所以:

if(x==y)\
{
    cout<<"x=y"<<endl;
}

实际上等同于:

if(x==y){
    cout<<"x=y"<<endl;
}