gecko-dev/xpcom/string/public/nsPrintfCString.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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#ifndef nsPrintfCString_h___
#define nsPrintfCString_h___
#ifndef nsString_h___
#include "nsString.h"
#endif
/**
* |nsPrintfCString| lets you use a formated |printf| string as an |const nsACString|.
*
* myCStr += nsPrintfCString("%f", 13.917);
* // ...a general purpose substitute for |AppendFloat|
*
* For longer patterns, you'll want to use the constructor that takes a length
*
* nsPrintfCString(128, "%f, %f, %f, %f, %f, %f, %f, %i, %f", x, y, z, 3.2, j, k, l, 3, 3.1);
*
* Exceding the default size (which you must specify in the constructor, it is not determined)
* causes an allocation, so avoid that. If your formatted string exceeds the allocated space, it is
* cut off at the size of the buffer, no error is reported (and no out-of-bounds writing occurs).
* This class is intended to be useful for numbers and short
* strings, not arbitrary formatting of other strings (e.g., with %s). There is currently no
* wide version of this class, since wide |printf| is not generally available. That means
* to get a wide version of your formatted data, you must, e.g.,
*
* CopyASCIItoUTF16(nsPrintfCString("%f", 13.917"), myStr);
*
* That's another good reason to avoid this class for anything but numbers ... as strings can be
* much more efficiently handled with |NS_LITERAL_[C]STRING| and |nsLiteral[C]String|.
*/
class NS_COM nsPrintfCString : public nsCString
{
typedef nsCString string_type;
enum { kLocalBufferSize=15 };
// ought to be large enough for most things ... a |long long| needs at most 20 (so you'd better ask)
// pinkerton suggests 7. We should measure and decide what's appropriate
public:
// XXX don't these need to be declared CDECL ??
explicit nsPrintfCString( const char_type* format, ... );
nsPrintfCString( size_type n, const char_type* format, ...);
private:
char_type mLocalBuffer[ kLocalBufferSize + 1 ];
};
#endif // !defined(nsPrintfCString_h___)