What's the Difference Between `_tmain()` and `main()` in C for Unicode Handling?

What is the Difference Between _tmain() and main() in C ?

In C , the main() function serves as the program's entry point, accepting one of two signatures:

int main();
int main(int argc, char* argv[]);

Alternatively, Microsoft has introduced extensions to accommodate Unicode support:

int wmain(int argc, wchar_t* argv[]);
int _tmain(int argc, char *argv[]);

_tmain() vs. main()

The key difference between _tmain() and main() lies in their usage with Unicode. If Unicode is enabled, _tmain() is compiled as wmain(), allowing it to handle wchar_t strings. Otherwise, it defaults to main().

Understanding the Character Interpretation

In your example, using _tmain() with char* arguments leads to unexpected behavior because the characters are interpreted differently. UTF-16, used by Windows when Unicode is enabled, represents ASCII characters as a pair of bytes, with the ASCII value followed by a null byte.

Due to the little-endian nature of the x86 CPU, these bytes are swapped, resulting in the ASCII value followed by a zero (a null byte). Since char strings are typically terminated by null bytes, your program interprets each argument as a single-character string.

Resolution

To resolve this, you have three options:

1. Explicitly Use Unicode: Call wmain() and use wchar_t for strings.
2. Explicitly Disable Unicode: Call main() and use char for strings.
3. Allow Both: Call _tmain() and use TCHAR as a macro for string types.

Remember that these extensions and concepts are specific to Microsoft and not part of standard C .

The above is the detailed content of What's the Difference Between `_tmain()` and `main()` in C for Unicode Handling?. For more information, please follow other related articles on the PHP Chinese website!