What is an auto keyword in C?

Yes, we can compile, but it can't be executed.

But, if we use #define, we can compile and run a C program without using the main() function. For example:

#include<stdio.h>    
#define start main    
void start() {    
   printf("Hello");    
}    

The argument passed to the main() function while executing the program is known as command line argument. For example:

main(int count, char *args[]){  
//code to  be executed  
}  

Brain Kernighan.

Brian Wilson Kernighan is a Canadian computer scientist. He worked at Bell Labs and contributed to the development of Unix alongside Unix creators Ken Thompson and Dennis Ritchie. Kernighan's name became widely known through co-authorship of the first book on the C programming language with Dennis Ritchie.

Born: 1 January 1942 (age 80 years), Toronto, Canada

Nationality: Canadian

A virtual address is composed of the selector and offset.

A near pointer doesn't have explicit selector whereas far, and huge pointers have explicit selector. When you perform pointer arithmetic on the far pointer, the selector is not modified, but in case of a huge pointer, it can be modified.

These are the non-standard keywords and implementation specific. These are irrelevant in a modern platform.