FStream class and using strings as parameters

Question

Deneme::Deneme(string FileName){

 fstream textfile;
 textfile.open(FileName);
 }

This gives me an error, but when I type textfile.open("randomname"); instead of textfile.open(FileName); there seems to be no problem. Why is this? It might be an easy question but I'm a beginner and couldn't find the solution of this.

Related: http://stackoverflow.com/questions/32332/why-dont-the-stdfstream-classes-take-a-stdstring — Etienne de Martel, Mar 13 '12 at 21:57

Jesse Good · Accepted Answer · 2012-03-13T22:34:00.813

1

fstreams only accept const char*. Use textfile.open(FileName.c_str()); or fstream textfile(FileName.c_str()); instead (although C++11 accepts const std::string&). Here is a handy site to look up how the constructors and functions are declared.

edited Mar 13 '12 at 22:34

answered Mar 13 '12 at 21:59

Jesse Good

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score 0 · Answer 2 · answered Mar 13 '12 at 21:59

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fstream's open method takes a const char pointer while you're passing in a std::string by value, I imagine this could be the error. Try:

textfile.open(FileName.c_str());

answered Mar 13 '12 at 21:59

Masci

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score 0 · Answer 3 · answered Mar 13 '12 at 22:30

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Use a standard C++ conforming system: C++2011 provides constructors and open() functions taking a std::string const&. For a pre-C++2011 system you need to use name.c_str() to pass to the file stream.

answered Mar 13 '12 at 22:30

Dietmar Kühl

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FStream class and using strings as parameters

3 Answers3