Printf-like assignment method for BString.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@40695 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kits/support/String.cpp

@@ -424,6 +424,25 @@ BString::AdoptChars(BString& string, int32 charCount)
 }
 
 
+BString&
+BString::SetToArguments(const char *format, ...)
+{
+	va_list arg;
+	va_start(arg, format);
+	int32 bytes = vsnprintf(LockBuffer(0), 0, format, arg);
+	va_end(arg);
+	UnlockBuffer(0);
+	
+	va_list arg2;
+	va_start(arg2, format);
+	bytes = vsnprintf(LockBuffer(bytes), bytes + 1, format, arg2);
+	va_end(arg2);
+	UnlockBuffer(bytes);
+
+	return *this;
+}
+
+
 //	#pragma mark - Substring copying