I was looking at MIT assignments and found this statement below link problem 2.5) option B)

https://ocw.mit.edu/courses/6-087-practical-programming-in-c-january-iap-2010/63515d4218cf01ba460623cbe9dc3b5c_MIT6_087IAP10_assn02_sol.pdf

Now it says

Assume (x=0,y=0,alliszero=1). alliszero =(x=1) && (y=0);

they are just asking to find statement will give error or not.
And in solution they are saying

’=’ operator should be replaced with ’==’. The correct version is
alliszero =(x==1) && (y==0);

consider below program

#include <stdio.h>
void main()
{

    int x =0 , y = 0 , alliszero =1;
    alliszero = (x = 1) && (y = 0);
    printf("%d",alliszero);

}

Now after I run this program then I am getting output as 0, But above they mentioned it as error, I am understanding that it might be one of the compiler dependent things then what is happening that doesn’t allow ‘=’ to work with ‘&&’ operator?