10. What is the Associativity of comma(i.e. ,) operator?

Ans:
Right to left.if you assign follwing way i=(2,3) , i get the value as 3.

Ex - 1: What is the output?

main()
{
float i=1.5;
switch(i)
{
case 1: printf("1");
case 2: printf("2");
default : printf("0");
}
}

Ans:
Compiler Error: switch expression not integral

Explanation:
Switch statements can be applied only to integral types.

Ex - 2: What is the output?
main()
{
extern i;
printf("%d\n",i);
{
int i=20;
printf("%d\n",i);
}
}

Ans:
Linker Error : Unresolved external symbol i

Explanation:
The identifier i is available in the inner block and so using extern has no use in resolving it.

Ex - 3: What is the output?

main()
{
int i=-1,j=-1,k=0,l=2,m;
m=i++&&j++&&k++||l++;
printf("%d %d %d %d %d",i,j,k,l,m);
}

Ans:
0 0 1 3 1

Explanation :
Logical operations always give a result of 1 or 0 . And also the logical AND (&&) operator has higher priority over the logical OR (||) operator. So the expression ‘i++ && j++ && k++’ is executed first. The result of this expression is 0 (-1 && -1 && 0 = 0). Now the expression is 0 || 2 which evaluates to 1 (because OR operator always gives 1 except for ‘0 || 0’ combination- for which it gives 0). So the value of m is 1. The values of other variables are also incremented by 1.