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我是編程新手，我是一名開始學習C++的學生。我想通過一本關於C++的好書讓我領先我的課，編程原則&練習（第二版）被推薦給我。 我在第一個練習叫「你好，世界！」我因爲一些編譯錯誤而被卡住了。 （我正在使用Visual Studio 2015）。Bjarne Stroustrup的頭文件編譯錯誤（PPP2 - 編程原理與實踐）
當我嘗試運行該程序的輸出顯示了這個
1>------ Rebuild All started: Project: Hello,World!, Configuration: Debug Win32 ------
1> Hello,World!.cpp
1>MSVCRTD.lib(exe_main.obj) : error LNK2019: unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" ([email protected]@YAHXZ)
1>F:\DAE v2015\1) Programming\C++ Projects\Hello,World!\Debug\Hello,World!.exe : fatal error LNK1120: 1 unresolved externals
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========
他的頭文件的代碼如下：
/*
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
預先感謝您的幫助！ PS：如果你認爲我應該從另一本書開始，因爲我可能遇到更多像這樣的問題，請告訴我:)
您能否顯示您的'Hello，World！.cpp'文件？ – atkins
這是我在Hello，World！.cpp文件中寫的唯一的東西： #include「F：\ DAE v2015 \ 1）Programming \ C++ Projects/std_lib_facilities.h」 – Feast
在這種情況下，就像@Mykola所說：你需要定義一個'int main（）'方法來使它成爲合法的C++程序。 – atkins