how can i skip those warnings? C++

Question

Code Added:

bool CHARACTER::SpamAllowBuf(const char *Message)
{
    if (!strcmp(Message, "(?˛´c)") || !strcmp(Message, "(μ·)") || !strcmp(Message, "(±a≫Y)") || !strcmp(Message, "(AA??)") || !strcmp(Message, "(≫c¶?)") || !strcmp(Message, "(?đłe)") || !strcmp(Message, "(??C?)") || !strcmp(Message, "(????)") || !strcmp(Message, "(AE??)"))
    {
        return true;
    }

    return false;
}

Warnings Gives :

char.cpp:7254:121: warning: trigraph ??) ignored, use -trigraphs to enable
char.cpp:7254:245: warning: trigraph ??) ignored, use -trigraphs to enable
char.cpp:7254:275: warning: trigraph ??) ignored, use -trigraphs to enable

How can i do to skip this warnings?

Answer 1

A trigraph sequence is any sequence of characters that starts with "??"; the next character determines the meaning of the sequence. Trigraph sequences are (or were) used to represent characters that weren't provided on some keyboards. So, for example, "??=" means #.

Trigraph sequences aren't widely used any more; I haven't checked, but they may well have been deprecated in C++ or removed entirely. (Thanks to @johnathan for pointing out that they were removed in C++17)

In any event, if you can't turn off that warning, you can change the character sequence so that it looks the same to the compiler but isn't a trigraph. To do that, change one of the ? characters to \?. So "??=" would become "?\?="; that's not a trigraph, because it doesn't consist of the characters "??" followed by another character, but once the compiler has processed it, it's two question marks followed by an '=' sign.

Another way to rearrange the quoted strings is to separate them. So "??=" would become "??" "=" or "?" "?="; the compiler concatenates those adjacent string literals, but, again, they're not trigraphs sequences because the concatenation occurs after checking for trigraphs.

Answer 2

To answer your question, use -Wno-trigraphs (if using gcc/clang).

But depending on the version of C++ you are using trigraphs are still part of the standard. Thus express sequences of questions marks like this "?" "?" "?" will avoid hitting the trigraph problem. The compiler will see a string of "???".