C++ spanish question mark

Question

I am beginning developing in C++ and I am developing a simple calculator in console and when my program ask to the user if wants to exit,the character \'¿\' doesn\'t appear

Answer 1

There are a few ways to deal with this problem.

The fundamental problem is not that the ¿ doesn't exist in the console, but that the console and your C++ text editor disagree on what that character is. The two are using different character codes for many characters beyond those needed for English. Character codes 32-126 (letters, numbers, punctuation and brackets), are universally the same. However, character codes 128 through 255, which from a Spanish point of view includes all the accented characters, "u with diaeresis" (e.g. "pingüino"), Ñ, and the starting ¿ and ¡, depend on the specific environment.

Why have such an inconvenient disagreement in character codes is a historical accident, interesting on its own but out of the scope of this question. To keep it simple: in the Windows OS, "consoles" (typically) use the list of characters described in OEM Code Page 437, while Windows applications like your C++ editor (typically) use the Windows-1252 Code Page.

There is no portable (universal) solution for this problem, because the issue of differing charsets is a platform-specific problem. Windows is unfortunately somewhat unique in that the editor and (console) outputs use different sets.

The first and simplest solution - which is fine for toy programs - is to just look up the character code that you want from the OEM 437 code-page, and use that. For ¿, that's #168 (0xa8 in hex, or \250 in octal). You can just embed the character code in the string to make clear what you're trying to do, either of these:

std::cout << ""\x0a8""Cu""\x0a0""l es el primer n""\x0a3""mero?\n"; // hex
std::cout << "\250Cu\240l es el primer n\243mero?\n";  // octal

Outputs:

¿Cuál es el primer número?

Note how I had to do the same thing with the ú and the á. Unfortunately, writing strings like this gets unwieldy quickly. using macros or const chars can help, but not much.

A second alternative is to use a Windows function such as CharToOemA. For example¹:

#include 
...
...
char pregunta[] = "¿Cuál es el primer número\n";
char *pregunta_oem  = new char[sizeof(pregunta)/sizeof(char)];
CharToOemA(pregunta, pregunta_oem);
std::cout << pregunta_oem;
delete []pregunta_oem;

For a more complex program, I would wrap that pattern into a utility function or class.

A different approach is to change the Code Page of the console, so that it agrees with your C++ editor and the rest of Windows. You can do that via the CHCP console command, or via the SetConsoleOutputCP() function, but that doesn't work on the default "raster font" used by consoles, so you have to change the font as well. When the font is set to a unicode font like Lucida Console, this works:

std::cout << "¿Cuál es el primer número?\n"; // ┐Cußl es el...
UINT originalCP = GetConsoleOutputCP();
SetConsoleOutputCP(1252);
std::cout << "¿Cuál es el primer número?\n"; // ¿Cuál es el...
SetConsoleOutputCP(originalCP);

(I don't know if you can change the font from the program itself; I have to look that up. The standard way to do it from the console is to click on the tiny icon on the corner, click Properties, Font tab, and pick a font from the list).

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1 I have to warn that this snippet contains a number of subtleties that can easily trip a beginner. You have to make sure the source of the text is a char array; if you're using a char pointer, sizeof won't work correctly and you have to use strlen(source)+1. For the source I used the natural option of a char array initialized to a literal, but you can't do that for the destination because the contents of such an array are read/only. If you are using a new'd char array or one that is not initialized to a literal, you can use the same char array for the source and destination. This example feels very C-like.