include ‘’ or provide a declaration of ‘exit’

Here is a response that includes the declaration of 'exit' in the C programming language:

#include <stdio.h>

int main() {
    int number;

    while (1) {
        printf("Enter a number (0 to exit): ");
        scanf("%d", &number);

        if (number == 0) {
            break;
        }

        printf("You entered: %d\n", number);
    }

    printf("Exiting...\n");

    return 0;
}

In this example, the program prompts the user to enter a number. If the user enters 0, the program breaks out of the loop and declares the exit. Otherwise, it prints the entered number and continues the loop until the user enters 0. Finally, it prints "Exiting..." before terminating the program.