Question

void FileIO :: openFile(const char* m_FileName,const char* m_FileMode);

我收到错误：

FileIO.cpp: In static member function ‘static void FileIO::openFile(const char*, const char*)’:
FileIO.cpp:12:45: error: no matching function for call to ‘std::basic_ifstream<char>::open(const char*&, const char*&)’
FileIO.cpp:12:45: note: candidate is:
In file included from FileIO.h:1:0:
/usr/include/c++/4.7/fstream:531:7: note: void std::basic_ifstream<_CharT, _Traits>::open(const char*, std::ios_base::openmode) [with _CharT = char; _Traits = std::char_traits<char>; std::ios_base::openmode = std::_Ios_Openmode]
/usr/include/c++/4.7/fstream:531:7: note:   no known conversion for argument 2 from ‘const char*’ to ‘std::ios_base::openmode {aka std::_Ios_Openmode}’

Answer 1

std::basic_ofstream::open不会两个 const char*。（注意：您的主题是ofstream，但是根据您的评论，您似乎在谈论ifstream）。

http://en.cppreference.com/w/cpp/io/basic_ifstream/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 ); (since C++11)

问题是第二个问题，而不是第一个问题。

ifstream ifs;
ifs.open("hello", "rb" /*<-- problem, this is a const char* not flags.*/);

相反，你需要传递它std :: ios_base flags

ifstream ifs("hello", std::ios_base::in | std::ios_base::binary);

或

ifstream ifs;
ifs.open("hello", std::ios_base::in | std::ios_base::binary);

---编辑---

查看帖子后面的评论（为什么不编辑帖子？）你也试图检查'NULL'。

在C和C ++中'NULL'是一个宏#define d为0.因此，检查NULL 可以检查空指针，但它也是可以测试数值。如果要检查文件是否已打开，则需要执行以下操作：

m_FileInput.open("hello", std::ios_base::in | std::ios_base::binary);
if (!m_FileInput.good()) // checks if the file opened.

如果可能，你应该尝试使用'nullptr'而不是'NULL'。

Answer 2

您尝试使用C＆＃39; FILE*语法来调用C ++ open函数。模式（读/写/追加）参数不是C ++中的字符串文字，但枚举值可能与OR一起。

g ++ ifstream匹配错误

2 个答案: