C++ File handling VS C file Handling query

[forumuser11@gmail.com]

If the fclose is not used in case of C, file remains open in the memory. In case of C++, fclose is called automatically and there is no memory leak.

Are there any plus/minus points of C++ file handling library (ifstream,ofstream) over C file handling library? Pl explain with example if possible.

[Paul McKenzie]

Originally Posted by forumuser11@gmail.com

If the fclose is not used in case of C, file remains open in the memory. In case of C++, fclose is called automatically

The fclose() function works the same way in C as it does C++. If you use fopen() in C++, you have to call fclose() yourself -- it isn't automatic.

Are there any plus/minus points of C++ file handling library (ifstream,ofstream) over C file handling library?

Streams can be overloaded, while fopen() and fclose() cannot be overloaded.

Pl explain with example if possible.

What's wrong with googling all of this info?

Regards,

Paul McKenzie

[ninja9578]

Try this:

struct FileOpen{
   FileOpen(FILE &* f, const char * name, const char * mode){
      f = fopen(name, mode);
      fp = f;
   }
   ~FileOpen(void){
      if (fp) fclose(fp);
   }
   FILE * fp;
};

FILE * myfile;
FileOpen fo(myfile, "c:\\test.txt", "w");
if (!myfile) return;

That code will automatically close your file for you.

[Lindley]

There are two primary advantages to streams over the printf family of functions:

1) Type safety
2) Polymorphism

By the first, I mean that it's impossible to have the types of errors you could get with printf, where you try to output a double using %d, and get garbage.

By the second, I mean that a FILE* is a FILE*, and you can't use it for much else. With streams, an ofstream is also an ostream, and you can define your own objects which are also ostreams, and all of your IO code can be written to ostreams and istreams with no regard to where the data is actually *going*.

Now, there are some advantages to the printf family over streams, as well:

1) Marginally faster in some cases (usually not a concern; IO is notoriously slow anyway)
2) More compact syntax can make the intended operation clearer
3) scanf() is capable of trying to match specific characters, which is a capability that istreams don't have (you'd need a regex package).

[laserlight]

Originally Posted by Lindley

2) More compact syntax can make the intended operation clearer

However, this can be mitigated by the use of the Boost.Format library.