《C++ Primer 中文版（第 5 版）》1.2

一个使用IO库的程序

#include "iostream"
#include "istream"
int main(){
    std::cout << "Enter two numbers:" << std::endl;
    int v1=0, v2=0;
    std::cin >> v1 >> v2;
    std::cout <<"The sum of" << v1 << " and " << v2
            <<" is " <<v1 +v2 <<std::endl;
    return 0;
}

因包含了<iostream>，报以下错误：

fatal error C1034: iostream: 不包括路径集

根据提示，应在环境变量中的系统变量中增加“include”项，以使代码能找到iostream，include的值为

D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023include

C:Program Files (x86)Windows Kits10Include10.0.10240.0ucrt

但这样会产生以下错误：

D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(19): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(19): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(20): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(22): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(29): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(29): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(30): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecstdlib(32): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(17): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(17): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(18): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(23): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(30): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(30): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(31): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(33): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(40): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(40): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(41): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(43): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(50): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(50): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(51): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(53): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(60): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(60): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(61): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(63): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(71): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(71): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(72): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(74): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(81): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(81): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(82): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(84): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(91): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(91): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(92): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(94): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(101): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(101): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(102): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(104): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(111): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(111): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(112): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(114): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(121): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(121): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(122): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(124): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(132): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(132): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(133): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(135): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(142): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(142): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(143): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(145): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(152): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(152): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(153): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(155): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(162): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(162): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(163): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(165): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(172): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(172): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(173): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(175): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(182): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(182): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(183): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(185): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(192): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(192): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(193): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(195): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(202): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(202): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(203): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(205): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(212): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(212): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(213): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(215): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(222): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(222): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(223): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(225): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(233): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(233): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(234): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(236): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(244): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(244): error C2059: 语法错误:“;”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(245): error C2449: 在文件范围内找到“{”(是否缺少函数头?)
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(250): error C2059: 语法错误:“}”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(258): error C2061: 语法错误: 标识符“noexcept”
D:Program Files (x86)Microsoft Visual Studio2017CommunityVCToolsMSVC14.16.27023includecmath(258): fatal error C1003: 错误计数超过 100；正在停止编译

根据https://blog.csdn.net/dawang_789/article/details/108104838此文章的提示，是因为VS是C++，不是C，扩展名应当是cpp，把文件名改成cpp，就好了。