What are the rules for assignment expressions in the C language?

The rules for assignment expressions in the C programming language are as follows:

1. The assignment operator “=” is used to assign the value of the expression on the right to the variable on the left.
2. The expression on the right can be a constant, variable, function call, arithmetic expression, relational expression, etc.
3. The variable on the left must be mutable (i.e., it cannot be a constant).
4. The assignment operator is right-to-left associative, meaning that the expression on the right is calculated first and then assigned to the variable on the left.
5. The value of the assignment expression is equal to the value of the expression on the right.
6. The assignment expressions can be nested, for example, a = b = c = 0; which assigns 0 to c, then assigns the value of c to b, and finally assigns the value of b to a.
7. The value of an assignment expression can be used as part of another expression. For example, a = b + (c = 10); assigns the value of 10 to c first, then calculates b + 10, and finally assigns the result to a.
8. The assignment operator has lower precedence than most other operators, like arithmetic, relational, and logical operators. To change the priority of an expression, parentheses can be used. For example, a = (b + c) * d; first calculate b + c, then multiply by d, and finally assign the result to a.
9. An assignment expression can be used to assign values to multiple variables simultaneously. For example, a = b = c = 0; assigns 0 to c, then assigns the value of c to b, and finally assigns the value of b to a. This allows for assigning values to multiple variables in a single statement.