First knowledge of C language - why does every C program have a main function

We're writing C When you program, you will find that every program has one main function , Why is that ？ every last C Are all procedures necessary ？

The answer is ： Yes ！！！

1. main function , Also called principal function , Is the starting point of program execution ,main Relatively speaking , Just as the tone of phonology theory is overtone , Overtone is division in program main Other functions besides , A pattern that caters to people's way of thinking rather than necessarily . There are masters and there are times , The implementation is clear , It can modularize the program and realize a closed whole .

2. In any one C In the program ,main Functions are essential ,main Function is the only entry of the program , in other words , Program runtime , First of all, from the main The function starts executing .
   Look at this code ：

#include <stdio.h>
int main()
{
    
    int n = 0;
    int count = 0;
    scanf("%d", &n);
    if (n < 12)
        count = 2;
    else
        count = n / 12 * 4 + 2;
    printf("%d\n", count);
    return 0;
}

3. At the same time, we should pay attention to one C The program must have and can only have one main function , If there are more than one in a program main function , Then something must go wrong .

#include <stdio.h>
int main()
{
    
	return 0;
}
int main()
{
    
	int a = 0;
	printf("%d\n", a);
	return 0;
}