COUT未聲明的std_lib_facilities

Question

我試圖用頭std_lib_facilities在我的代碼，但我覺得我做了錯事，因爲當我嘗試使用此代碼：

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

它給了我這個錯誤

Error C2065 'cout': undeclared identifier 

我std_lib_facilities是在項目文件夾，它是在頭標籤在我的Visual Studio 2015年std_lib_facilities的代碼是這樣的：

/* 
    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 

有人知道我在做什麼錯？

Answer 1

我看到您在stdafx.h之前包含了../std_lib_facilities.h。我們來考慮一下stdafx.h是什麼。這是一個precompiled header。

stdafx.h是由Microsoft Visual Studio IDE嚮導生成的一個文件，它描述經常使用但幾乎不會更改的標準系統和項目特定包含文件。

兼容的編譯器（例如，Visual C++ 6.0和更新版本）將預編譯該文件以減少整體編譯時間。 Visual C++ 不會在源文件中的#include「stdafx.h」之前編譯任何東西，除非編譯選項/Yu'stdafx.h未被選中（默認情況下）;它假定源代碼中的所有代碼都已經編譯完成幷包含該行。

如果包含標準頭文件的部分未編譯，則會出現缺失聲明的錯誤。

解決方案：在文件頂部包含stdafx.h，或根本不使用預編譯頭，或者確保未選中相應的選項。

Answer 2

將using std::cout;或using namespace std;放在包含main()函數的文件中。 或者只是在cout與std::之間加上前綴。