Difference between <cstring> and <string>
C++Visual StudioG++C++ Problem Overview
Earlier today (actually yesterday due to my time-zone) I was attempting a programming interview using Visual Studio 2012 for C++ on Interview Street (which uses g++).
To be brief, I came across several compilation errors1 when I was using
#include <cstring>
which was provided by the skeleton code in one of the question, and after turning to
#include <string>
all compilation errors magically disappeared.
However, upon submission to Interview Street, I had to add c back; otherwise I got compilation errors.
It was the first time I was bitten by non-standardization....
My question is: what inside <string> and <cstring> took me (precious) more than half an hour?
1 For anyone who is curious:
One error by Visual Studio 2012 if using <cstring> is:
>error C2338: The C++ Standard doesn't provide a hash for this type.
in
>c:\program files (x86)\microsoft visual studio 11.0\vc\include\xstddef
possibly for string as key in unordered_map
One error by g++ if using <string> is:
>'strlen' was not declared in this scope
C++ Solutions
Solution 1 - C++
The cstring header provides functions for dealing with C-style strings — null-terminated arrays of characters. This includes functions like strlen and strcpy. It's the C++ version of the classic string.h header from C.
The string header provides the std::string class and related functions and operators.
The headers have similar names, but they're not really related beyond that. They cover separate tasks.
Solution 2 - C++
<cstring> has the C string code from the C header string.h. C++ has a convention where C headers have the same base name, except for a leading c and no trailing .h. All the contents are available under the std:: namespace.
<string> has the standard library std::string and related functions
Solution 3 - C++
In C++, you wouldn't use #include <somefile.h>, but instead #include <somefile>. Now C++ has its string classes in <string>, but the c-string functions are also available, which would be in <string.h>. C++ uses <cstring> and <string>