# C main() return

**[main() return](https://en.cppreference.com/w/c/language/main_function)** value is the program's [[c-exit-status]], communicated to the shell via the `$?` variable. Returning 0 indicates success (`EXIT_SUCCESS`); non-zero indicates failure (`EXIT_FAILURE`, typically 1). The shell can check this status with `echo $?` or use it in conditionals and pipelines.

Always explicitly return `EXIT_SUCCESS` or `EXIT_FAILURE` from main to make intent clear.

## Example

This example demonstrates returning different exit statuses based on program logic.

```c
// compile: gcc -o mainreturn mainreturn.c
// run: ./mainreturn 5; echo $?
// description: return exit status from main to signal success or failure

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <number>\n", argv[0]);
        return EXIT_FAILURE;
    }
    
    int num = atoi(argv[1]);
    if (num > 0) {
        printf("Positive number: %d\n", num);
        return EXIT_SUCCESS;
    } else {
        fprintf(stderr, "Error: number must be positive\n");
        return EXIT_FAILURE;
    }
}
```