What's the reason of GCC warnings for converting an string constant to 'TCHAR *'?

I’m recently starting programing C Windows API from Charles Petzold, and somewhere we must write a header contain a lot of similar lines like below:

SM_CXSCREEN,            TEXT ("SM_CXSCREEN"), 
                            TEXT ("Screen width in pixels"),

and after use this header in a program, the GCC warning me like this:

ISO C++ forbids converting a string constant to ‘TCHAR*’ {aka ‘char*’} [-Wwrite-strings]gcc

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I hope to understand more about this specific warning.

>Solution :

The error "ISO C++ forbids converting a string constant to TCHAR* {aka char*}" occurs because in C++, string literals like "example" are of type const char[] (or const wchar_t[] for wide-character literals like L"example"). However, you are trying to assign or pass them to a non-const pointer type like TCHAR* (or char*).

This is dangerous because modifying a string literal is undefined behaviour – thus warning