c++ - 错误 : no matching function for call to 'std::basic_ifstream::basic_ifstream(std::__cxx11::string&)'

Question

我正在尝试编写一个程序来打开一个文件并计算该文件中以空格分隔的单词数。

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main() {
    string filepath;
    cout << "Enter the file path including the file name:" << endl;
    cin >> filepath; 
    ifstream f(filepath);
    int nwords = 0;
    string word;
    while (f >> word)
        ++nwords;
    cout << "Number of words = " << nwords << endl;
}

这是我尝试编译时的错误。

g++ Assignment1.cpp
Assignment1.cpp: In function 'int main()':
Assignment1.cpp:10:21: error: no matching function for call to 'std::basic_ifstream<char>::basic_ifstream(std::__cxx11::string&)'
  ifstream f(filepath);
                     ^
In file included from Assignment1.cpp:2:0:
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:495:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]
       basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
       ^
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:495:7: note:   no known conversion for argument 1 from 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' to 'const char*'
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:481:7: note: candidate: std::basic_ifstream<_CharT, _Traits>::basic_ifstream() [with _CharT = char; _Traits = std::char_traits<char>]
       basic_ifstream() : __istream_type(), _M_filebuf()
       ^
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:481:7: note:   candidate expects 0 arguments, 1 provided
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:455:11: note: candidate: std::basic_ifstream<char>::basic_ifstream(const std::basic_ifstream<char>&)
     class basic_ifstream : public basic_istream<_CharT, _Traits>
           ^
c:\mingw\lib\gcc\mingw32\5.3.0\include\c++\fstream:455:11: note:   no known conversion for argument 1 from 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' to 'const std::basic_ifstream<char>&'

Answer 1

g++ -std=c++11 Assignment1.cpp

应该可以。问题是这些年来 C++ 有不同的标准。标准混杂。根据我的经验，你在编译时看到的 90% 的错误都与 ios 有关，要么是用 gcc 编译的，要么是标准错误。抱歉，我不能确定；我不使用 Windows。