`_tmain() vs. main(): When Should I Use Each in C ?`

Difference Between _tmain() and main() in C

In C , the primary method for defining the program's entry point is main(), which typically appears with the signature:

int main();

Alternatively, Microsoft has introduced a platform-specific extension called _tmain(), which offers a convenient way to handle character encoding in Windows environments.

The primary difference between _tmain() and main() lies in their handling of character encoding. While main() expects arguments of the type char*, _tmain() allows for both char* and wchar_t* arguments, depending on whether Unicode is enabled for the compiled code. This extension is intended to simplify the transition between Unicode and multibyte character sets on Windows platforms.

If Unicode is enabled during compilation, _tmain() will be compiled as wmain() and will accept arguments of the type wchar_t*. Conversely, if Unicode is disabled, _tmain() will be compiled as main() and accept arguments of the type char*.

However, it's important to note that using _tmain() and specifying char* as the argument type may lead to unintended behavior when working with Unicode-enabled code, as observed in the example provided in the question. This is because main() expects wchar_t* arguments in Unicode mode, leading to incorrect interpretation and display of Unicode strings.

To resolve this issue, it is recommended to adhere to the following guidelines when working with character encoding in Windows environments:

• Explicitly enable or disable Unicode throughout the codebase:

  • For Unicode, use wmain() and wchar_t* for strings.
  • For non-Unicode, use main() and char* for strings.

• Allow for both Unicode and non-Unicode mode using macros:

  • Use _tmain() and define TCHAR to resolve to either char or wchar_t depending on Unicode compatibility mode.
  • Employ the -T- version of string types defined in windows.h to handle character encoding consistently.

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