Why Does Recursively Calling `main()` Lead to Undefined Behavior in C ?

Calling main to call main: An Undefined Quest

The code snippet below has raised questions among programmers:

int main () { 
    return main(); 
}

It compiles without errors but fails to terminate execution, leading to speculation about its behavior.

Undefined Behavior: The Enigma of main

According to the C standard, [basic.start.main](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0689r2.html#3.6.1) states that "The function main shall not be named by an expression." This implies that calling main within the program is prohibited.

Compiler Behavior: Warnings or Silence?

Compilers may handle this specific case differently. GCC, with the -pedantic option enabled, issues a warning about the illegal use of main. Visual Studio, however, remains silent, opting not to warn about the recursive nature of the code.

What Happens When You Call main?

The answer to this question lies within the realm of undefined behavior. The standard does not define what should happen when main is called within the program. As a result, any observed behavior is unpredictable and implementation-dependent.

Conclusion

Calling main within the program is an undefined action, and its behavior cannot be reliably predicted. Compilers may handle this case differently, issuing warnings or failing to compile altogether. Attempting to define the outcome of undefined behavior is futile and can lead to unexpected and potentially hazardous results.

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