Is Recursively Calling `main()` Allowed in C ?

Calling Main Function Recursively in C

The code snippet provided attempts to call the main() function recursively within itself in C . However, it's important to note that this behavior is not allowed in strict C compliance.

Is Recursively Calling main() Allowed in C ?

According to the C Standard, a function cannot call itself directly, including the main() function. This restriction is intended to prevent infinite recursion and guarantee program termination.

Practical Implementation with g

Despite the language standard, it's possible to call main() recursively in practice using the GNU C compiler (g ). g doesn't strictly enforce the standard in this regard, allowing code with recursive main() calls to compile and execute.

Example Code

The following modified code snippet demonstrates recursive main() calls using g :

<code class="cpp">#include <cstdlib>
#include <iostream>
using namespace std;

int main() {
    int y = rand() % 10; // returns 3, then 6, then 7
    cout << "y = " << y << endl;
    return (y == 7) ? 0 : main();
}</code>

When compiled and executed, this code will generate the following output:

y = 3
y = 6
y = 7

Assembly Analysis

Examining the assembly generated for this code reveals that g treats recursive main() calls like any other function call:

main:
        ...
        cmpl    , -12(%rbp)
        je      .L7
        call    main
        ...
.L7:
        ...
        leave
        ret

Note:

While this behavior is possible with g , it's crucial to note that it's not guaranteed. Other compilers may adhere strictly to the C Standard, resulting in compilation errors or unexpected behavior. Therefore, using recursive main() calls is not a recommended practice.

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