COUT未声明的std_lib_facilities

Question

我试图用头std_lib_facilities在我的代码，但我觉得我做了错事，因为当我尝试使用此代码：

#include "../std_lib_facilities.h" 
#include "stdafx.h" 
int main() 
{ 
    cout<<"Hello, World!\n"; 
    return 0; 
} 

它给了我这个错误

Error C2065 'cout': undeclared identifier 

我std_lib_facilities是在项目文件夹，它是在头标签在我的Visual Studio 2015年std_lib_facilities的代码是这样的：

/* 
    std_lib_facilities.h 
*/ 

/* 
    simple "Programming: Principles and Practice using C++ (second edition)" course header to 
    be used for the first few weeks. 
    It provides the most common standard headers (in the global namespace) 
    and minimal exception/error support. 

    Students: please don't try to understand the details of headers just yet. 
    All will be explained. This header is primarily used so that you don't have 
    to understand every concept all at once. 

    By Chapter 10, you don't need this file and after Chapter 21, you'll understand it 

    Revised April 25, 2010: simple_error() added 

    Revised November 25 2013: remove support for pre-C++11 compilers, use C++11: <chrono> 
    Revised November 28 2013: add a few container algorithms 
    Revised June 8 2014: added #ifndef to workaround Microsoft C++11 weakness 
*/ 

#ifndef H112 
#define H112 251113L 


#include<iostream> 
#include<iomanip> 
#include<fstream> 
#include<sstream> 
#include<cmath> 
#include<cstdlib> 
#include<string> 
#include<list> 
#include <forward_list> 
#include<vector> 
#include<unordered_map> 
#include<algorithm> 
#include <array> 
#include <regex> 
#include<random> 
#include<stdexcept> 

//------------------------------------------------------------------------------ 


//------------------------------------------------------------------------------ 

typedef long Unicode; 

//------------------------------------------------------------------------------ 

using namespace std; 

template<class T> string to_string(const T& t) 
{ 
    ostringstream os; 
    os << t; 
    return os.str(); 
} 

struct Range_error : out_of_range { // enhanced vector range error reporting 
    int index; 
    Range_error(int i) :out_of_range("Range error: "+to_string(i)), index(i) { } 
}; 


// trivially range-checked vector (no iterator checking): 
template< class T> struct Vector : public std::vector<T> { 
    using size_type = typename std::vector<T>::size_type; 

#ifdef _MSC_VER 
    // microsoft doesn't yet support C++11 inheriting constructors 
    Vector() { } 
    explicit Vector(size_type n) :std::vector<T>(n) {} 
    Vector(size_type n, const T& v) :std::vector<T>(n,v) {} 
    template <class I> 
    Vector(I first, I last) : std::vector<T>(first, last) {} 
    Vector(initializer_list<T> list) : std::vector<T>(list) {} 
#else 
    using std::vector<T>::vector; // inheriting constructor 
#endif 

    T& operator[](unsigned int i) // rather than return at(i); 
    { 
     if (i<0||this->size()<=i) throw Range_error(i); 
     return std::vector<T>::operator[](i); 
    } 
    const T& operator[](unsigned int i) const 
    { 
     if (i<0||this->size()<=i) throw Range_error(i); 
     return std::vector<T>::operator[](i); 
    } 
}; 

// disgusting macro hack to get a range checked vector: 
#define vector Vector 

// trivially range-checked string (no iterator checking): 
struct String : std::string { 
    using size_type = std::string::size_type; 
// using string::string; 

    char& operator[](unsigned int i) // rather than return at(i); 
    { 
     if (i<0||size()<=i) throw Range_error(i); 
     return std::string::operator[](i); 
    } 

    const char& operator[](unsigned int i) const 
    { 
     if (i<0||size()<=i) throw Range_error(i); 
     return std::string::operator[](i); 
    } 
}; 


namespace std { 

    template<> struct hash<String> 
    { 
     size_t operator()(const String& s) const 
     { 
      return hash<std::string>()(s); 
     } 
    }; 

} // of namespace std 


struct Exit : runtime_error { 
    Exit(): runtime_error("Exit") {} 
}; 

// error() simply disguises throws: 
inline void error(const string& s) 
{ 
    throw runtime_error(s); 
} 

inline void error(const string& s, const string& s2) 
{ 
    error(s+s2); 
} 

inline void error(const string& s, int i) 
{ 
    ostringstream os; 
    os << s <<": " << i; 
    error(os.str()); 
} 


template<class T> char* as_bytes(T& i) // needed for binary I/O 
{ 
    void* addr = &i; // get the address of the first byte 
         // of memory used to store the object 
    return static_cast<char*>(addr); // treat that memory as bytes 
} 


inline void keep_window_open() 
{ 
    cin.clear(); 
    cout << "Please enter a character to exit\n"; 
    char ch; 
    cin >> ch; 
    return; 
} 

inline void keep_window_open(string s) 
{ 
    if (s=="") return; 
    cin.clear(); 
    cin.ignore(120,'\n'); 
    for (;;) { 
     cout << "Please enter " << s << " to exit\n"; 
     string ss; 
     while (cin >> ss && ss!=s) 
      cout << "Please enter " << s << " to exit\n"; 
     return; 
    } 
} 



// error function to be used (only) until error() is introduced in Chapter 5: 
inline void simple_error(string s) // write ``error: s and exit program 
{ 
    cerr << "error: " << s << '\n'; 
    keep_window_open();  // for some Windows environments 
    exit(1); 
} 

// make std::min() and std::max() accessible on systems with antisocial macros: 
#undef min 
#undef max 


// run-time checked narrowing cast (type conversion). See ???. 
template<class R, class A> R narrow_cast(const A& a) 
{ 
    R r = R(a); 
    if (A(r)!=a) error(string("info loss")); 
    return r; 
} 

// random number generators. See 24.7. 



inline int randint(int min, int max) { static default_random_engine ran; return uniform_int_distribution<>{min, max}(ran); } 

inline int randint(int max) { return randint(0, max); } 

//inline double sqrt(int x) { return sqrt(double(x)); } // to match C++0x 

// container algorithms. See 21.9. 

template<typename C> 
using Value_type = typename C::value_type; 

template<typename C> 
using Iterator = typename C::iterator; 

template<typename C> 
    // requires Container<C>() 
void sort(C& c) 
{ 
    std::sort(c.begin(), c.end()); 
} 

template<typename C, typename Pred> 
// requires Container<C>() && Binary_Predicate<Value_type<C>>() 
void sort(C& c, Pred p) 
{ 
    std::sort(c.begin(), c.end(), p); 
} 

template<typename C, typename Val> 
    // requires Container<C>() && Equality_comparable<C,Val>() 
Iterator<C> find(C& c, Val v) 
{ 
    return std::find(c.begin(), c.end(), v); 
} 

template<typename C, typename Pred> 
// requires Container<C>() && Predicate<Pred,Value_type<C>>() 
Iterator<C> find_if(C& c, Pred p) 
{ 
    return std::find_if(c.begin(), c.end(), p); 
} 

#endif //H112 

有人知道我在做什么错？

Answer 1

我看到您在stdafx.h之前包含了../std_lib_facilities.h。我们来考虑一下stdafx.h是什么。这是一个precompiled header。

stdafx.h是由Microsoft Visual Studio IDE向导生成的一个文件，它描述经常使用但几乎不会更改的标准系统和项目特定包含文件。

兼容的编译器（例如，Visual C++ 6.0和更新版本）将预编译该文件以减少整体编译时间。 Visual C++ 不会在源文件中的#include“stdafx.h”之前编译任何东西，除非编译选项/Yu'stdafx.h未被选中（默认情况下）;它假定源代码中的所有代码都已经编译完成并包含该行。

如果包含标准头文件的部分未编译，则会出现缺失声明的错误。

解决方案：在文件顶部包含stdafx.h，或根本不使用预编译头，或者确保未选中相应的选项。

Answer 2

将using std::cout;或using namespace std;放在包含main()函数的文件中。 或者只是在cout与std::之间加上前缀。