Why Does Concatenation Seem to Take Precedence Over Addition in PHP?

PHP Operators Precedence Confusion with Addition and Concatenation

When dealing with different operators in PHP, understanding their precedence becomes crucial. The precedence determines the order in which operations are performed, which can lead to unexpected results.

In the given example:

<code class="php">$a = 1;
$b = 2;

echo "sum: " .  $a + $b;
echo "sum: " . ($a + $b);</code>

The issue arises because both the addition ( ) and concatenation (.) operators share the same precedence. However, as they are left associative, they are evaluated from left to right.

In the first echo statement, the code gets evaluated as:

<code class="php">echo (("sum:" . $a) + $b);</code>

This means that the concatenation "sum:" and $a are first evaluated, resulting in "sum: 1". This is then added to $b, giving the output of 2.

On the other hand, in the second echo statement, parentheses are used:

<code class="php">echo ("sum: " . ($a + $b));</code>

The parentheses force the addition of $a and $b to be evaluated first, giving the result of 3. This is then concatenated with "sum: ", resulting in the expected output of "sum: 3".

This behavior can be confusing, especially when dealing with multiple operators with the same precedence. However, by understanding operator precedence and associativity, developers can avoid such unexpected results.

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