C Formatting Using STL

With wxWidgets, the wxString class is very similar to the STL string class, but the STL does not include a Format function as does wxString.

As you may know, you can say

wxString str = wxString::Format ("%s %i", "whatever", 12345);

and the variable str will be formatted like in C using sprintf

sprintf (buffer, "%s %i", "whatever", 12345);

Is there a Format() function in the STL for strings or something similar? Right now I use standard C strings rather than the STL because this very reason (I want to go to STL, but this is the only drawback). I know I could use osstringstream to get similar functionality, but I would rather use a C approach.

Any ideas?

I don't believe there is a standard format function for STL strings (just use stringstreams!), but you can try the Boost Format Library (just use stringstreams!). Otherwise I think you are stuck with sprintf and C style strings (just use stringstreams!).

wxString str = wxString::Format ("%s %i", "whatever", 12345);

Like what jlou said... If you want to format a std::string in the same way as the above wxString you would need to use a stringstream container to handle the formating as an intermediate step.

Code:

#include <string>
#include <sstream>
...
std::string input("whatever");
int i = 12345;
std::stringstream format;
std::string str;
...
format << input << ' ' << i;  // Store/format data into stringstream
str = format.str();  // str now equals "whatever 12345"

Could also skip the use of variables above and just directly say:

Code:

format << "whatever" << ' ' << 12345;
str = format.str();

Are you SURE there is no other way using the STL?

I am not positive, since I don't know every function in the STL, but I am 99% sure. You would have to use a third party library (like boost), write your own version (someone in my company did) or use stringstreams.

The reason one is not available is because sprintf is not type-safe and is easy to make mistakes with that cannot be caught by the compiler. I believe they tried to avoid providing functionality like that in the C++ standard library.