尝试使用带有infile.open（）的字符串变量在c ++中被视为char [英] Trying to use a string variable with infile.open() is treated as a char in c++

问题描述

我试图创建一个程序，用户输入一个文件名，然后程序尝试打开它，并检查它是否是打开的。我使用getline函数。这是我的代码到目前为止：

I'm trying to make a program where the user enters a file name and then the program tries opening it and checks to see if it is open. I am using the getline function. Here is my code so far:

#include <iostream>
#include <string>
#include <fstream>

using namespace std;


void readGameFile();

int main()
{
    readGameFile();
    return 0;
}


void readGameFile()
{
    ifstream infile;
    string s;
    string fileName;
    getline(cin,fileName);
    infile.open(fileName);
    if(infile.is_open())
    {
        cout << "It worked!"<<endl;
    }
    else
    {
        cout << "You messed up"<<endl;  
    }
}

它给我这个错误：
23 ：22：error：没有匹配的函数调用'std :: basic_ifstream :: open（std :: string&）'

It gives me this error: 23:22: error: no matching function for call to ‘std::basic_ifstream::open(std::string&)’

23:22： ：
/usr/include/c++/4.6/fstream:531:7：note：void std :: basic_ifstream< _CharT，_Traits> :: open（const char *，std :: ios_base :: openmode） _CharT = char，_Traits = std :: char_traits，std :: ios_base :: openmode = std :: _ Ios_Openmode]
/usr/include/c++/4.6/fstream:531:7：注意：没有已知的参数转换1从'std :: string {aka std :: basic_string}'到'const char *'

23:22: note: candidate is: /usr/include/c++/4.6/fstream:531:7: note: void std::basic_ifstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char, _Traits = std::char_traits, std::ios_base::openmode = std::_Ios_Openmode] /usr/include/c++/4.6/fstream:531:7: note: no known conversion for argument 1 from ‘std::string {aka std::basic_string}’ to ‘const char*’

所以，我不确定是什么问题。我是相当新的编程，我试图找出一个类项目（这不是任务，它只是一个通用版本的问题，我在我的项目到目前为止）。如果你能给任何帮助，那将是巨大的。谢谢！

So, I'm not really sure what the problem is. I'm fairly new to programming, I'm trying to figure this out for a class project(this isn't the assignment, it's just a generic version of the problem I'm having in my project so far). If you can give any help, that would be great. Thanks!

推荐答案

open ：

void open( const char *filename, ios_base::openmode mode = ios_base::in );
void open( const std::string &filename, ios_base::openmode mode = ios_base::in );

第二个只能从C ++ 11开始使用。你显然不是编译在C ++ 11模式或使用过期的编译器。还有另一个重载，需要 const char * ，所以这应该工作不管：

The second one is only available since C++11. You are apparently either not compiling in C++11 mode or using an out of date compiler. There is another overload that takes const char*, so this should work regardless:

infile.open(fileName.c_str());

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