Comma operator should be used carefully
In C and C++, comma is the last operator in precedence table. So comma should be carefully used on right side of an assignment expression. For example, one might expect the output as b = 10 in below program. But program prints b = 20 as assignment has higher precedence over comma and the statement “b = 20, a” becomes equivalent to “(b = 20), a”.
#include<stdio.h>int main(){ int a = 10, b; b = 20, a; // b = 20 printf(" b = %d ", b); getchar(); return 0;} |
Putting a bracket with comma makes b = a (or 10).
#include<stdio.h>int main(){ int a = 10, b; b = (20, a); // b = a printf(" b = %d ", b); getchar(); return 0;} |
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