This happens because the expression is treated as You'll get a Notice: Undefined variable: a Something that threw me of guard and I hadn't found it mentioned anywhere is if you're looking to asign a value in an if statement condition and use the same value in the said condition and compare it to a different value note the precedence of operators.

Los operadores de igual precedencia que no son asociativos no pueden usarse '=', por otra parte, tieneĪsociatividad a derecha, así $a = $b = $c se agrupa como Por ejemplo '-' tiene asociatividad a izquierda, así PorĬuando los operadores tienen igual precedencia su asociatividad decideĬómo se agrupan. Los paréntesis pueden ser usados para forzar la precedencia, si es necesario. Tiene una precedencia mayor que el operador de adición ('+'). Por ejemplo, en la expresión 1 +ġ8 porque el operador de multiplicación ('*') La precedencia de un operador indica qué tan 'estrechamente' se unen dosĮxpresiones juntas.

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Orden de operaciones definicion