Why output of this code is 3?

Question

Just why? (Language: C)

#include <stdio.h>
int main(void) {
int smth = (1, 2, 3);
printf("%d", smth); // 3. why..?
}

https://code.sololearn.com/cZrx2DPFzk4a/?ref=app

Answer 1

It is the comma operator

i = a, b, c; // stores a into i
i = (a, b, c); // stores c into i

the differing behavior between the first and second lines is due to the comma operator having lower precedence than assignment.

Also '()' operator has higher precedence than '='. So , firstly, bracket operator is evaluated. '()' operator is operated from left to right. but it is always the result of last that gets assigned.

Answer 2

RKK Wow, so fast! Thank you very much!