How Does C Evaluate Chained Comparison Operators Like (4 > y > 1)?

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Chained Logical Operators: Evaluating (4 > y > 1) in C

The statement (4 > y > 1) in C may seem logical, but its evaluation follows a specific order of operations.

Parsing and Order of Evaluation

The statement is parsed as ((4 > y) > 1). Comparison operators (< and >) are evaluated left-to-right. The expression 4 > y returns 0 if true and 1 if false. This result is then compared to 1.

Result Evaluation

Since 0 or 1 is never greater than 1, the entire statement will always return false. However, an exception occurs when y is an object of a class where the > operator is overloaded. In such cases, the overloaded operator's behavior determines the result.

Overloading Exception

Consider the following code snippet:

class mytype{};

mytype operator>(int x, const mytype &y) {
    return mytype();
}

int main() {
    mytype y;
    cout << (4 > y > 1) << endl;

    return 0;
}

In this example, where y is of class mytype and the > operator is overloaded, the code will fail to compile.

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