no number->string conversion in stdc++?

Hello.

I learnt today to my dismay that there is in fact no number to string conversion function in the standard C++ library? I can't do simple natural things like:

std :: string a ( 2 ) ;
std :: string b ( 2.5 ) ;

without errors at compilation talking about "no matching function for call".

I find it difficult to believe that no-one thought this was necessary enough to be included in the C++ standard basic_string class.

The three ways out of this problem I got to know:

1. stringstream from std, resulting in somewhat unweildy operations
2. lexical_cast from boost, resulting in dependency on huge boost lib
3. QString from Qt, resulting in depdency on huge Qt lib

Of course stdc++ is also a huge lib, but thought I can expect stdc++ to be there on more machines than boost or Qt.

So shall I go with std::string and std::stringstream, std::string and boost::lexical_cast or simply Qt's QString? QString seems most appealing, but I would listen to your better judgment.

Shriramana Sharma.

These conversions are neither simple nor natural.

Look at the printf() documentation, and note how much of it applies to formatting numeric values. Base, precision, field width, leading zeroes/spaces, exponential notation. And that's aside from locale issues (e.g. decimal separator), which aren't described there.

If the std::ostream formatting operators are sufficient, then use std::ostringstream, otherwise write your own.

Don't use substantial external libraries just for a few utility functions.

Glynn Clements <[email protected]>