PHP interview questions: $ a + $ a ++ and $ a + $ a ++

The results of $ a + $ a ++ and $ a + $ a ++ are almost always wrong for many programmers, so what is the final result of $ a + $ a ++ and $ a + $ a ++? Let's take a look. let's take a look... the results of $ a + $ a ++ and $ a + $ a ++ are almost always wrong for many programmers, so what is the final result of $ a + $ a ++ and $ a + $ a ++? Let's take a look.

Let's take a look at the question:

$ A = 1;

$ B = $ a + $ a ++; // Result: $ a = 2, $ B = 3

This question is not very difficult. Obviously, the priority of ++ in PHP is higher than that of ++. Therefore, execute $ a ++ first. then, the value of $ a is 2.

Next question:

$ A = 1;

$ B = $ a + $ a ++;

What is the value of $ B? The answer is: 3.

Why is it 3? Isn't it higher than ++'s priority? After $ a ++ is executed, the value of $ a should be 2 and the result is 5. in fact, this is the correct answer: 3. at first, I thought it should be 5.

Explanation:Operators are combined from the left to the right. the above expression is equivalent

$ = ($ A + $ a) + $ a ++

Based on the left-hand combination principle:

// Calculate $ a + $ a $ B = 2 + $ a ++ first; // at this time, we need to compare the operator priorities of ++ and ++. $ B = 2 + 1; // $ a = 2

This is a tough PHP pen question. brackets should be used in the actual project code to avoid these problems.

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