How can I get a file's size in C++?

c++ filesize
Sophie Sperner picture Sophie Sperner · Apr 30, 2011 · Viewed 284.6k times · Source

Let's create a complementary question to this one. What is the most common way to get the file size in C++? Before answering, make sure it is portable (may be executed on Unix, Mac and Windows), reliable, easy to understand and without library dependencies (no boost or qt, but for instance glib is ok since it is portable library).

Answer

Spyros picture Spyros · Apr 30, 2011 
#include <fstream>

std::ifstream::pos_type filesize(const char* filename)
{
    std::ifstream in(filename, std::ifstream::ate | std::ifstream::binary);
    return in.tellg(); 
}

See http://www.cplusplus.com/doc/tutorial/files/ for more information on files in C++.

edit: this answer is not correct since tellg() does not necessarily return the right value. See http://stackoverflow.com/a/22986486/1835769

Related questions

Using C++ filestreams (fstream), how can you determine the size of a file?

I'm sure I've just missed this in the manual, but how do you determine the size of a file (in bytes) using C++'s istream class from the fstream header?

Read More
Portable way to get file size in C/C++

I need to determin the byte size of a file. The coding language is C++ and the code should work with Linux, windows and any other operating system. This implies using standard C or C++ functions/classes. This trivial need …

Read More
C++ stat.h incomplete type and cannot be defined

I am having a very strange issue with stat.h At the top of my code, I have declarations: #include <sys\types.h> #include <sys\stat.h> And function prototype: int FileSize(string szFileName); Finally, the …

Read More