lvalue required as left operand of assignment c

Question

at this code

(nr % 10) % 2 == 0 ? a[i] = nr % 10 + 1 : a[i] = nr % 10;

I get a lvalue required as left operand of assignment. Can anyone help me with this?

Answer 1

The overall problem with this code is that conditional operator is an expression, not a statement. Although you can use assignment expressions as its part, it's better to do the assignment of the whole expression, like this:

a[i] = (nr % 2) == 0 ? nr % 10 + 1 : nr % 10;
//     ^^^^^^^^
// No need to obtain a remainder of division by 10,
// because 2 is a divisor of 10.

Note: You could avoid the conditional altogether with a simple trick:

a[i] = nr % 10 + (1 - (nr % 2));

Answer 2

Put parentheses around your last assignment to solve this:

(nr % 10) % 2 == 0 ? a[i] = nr % 10 + 1 : (a[i] = nr % 10);

This is because assignment has a lower precedence than the ternary operator so code like a = b ? d : c is parsed as a = (b ? c : d) and not as (a = b) ? c : d. The assignment between ? and : doesn't need to be placed in parentheses as there isn't any syntactic ambiguity.

Answer 3

You have to use:

a[i] = (nr % 10) % 2 == 0 ? nr % 10 + 1 : nr % 10;