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PHP

jough
jough
12,984 Points
Posted by jough
jough
12,984 Points

basic PHP Quiz question: Why does this evaluate to true?

Why does this evaluate to true? <?php $a = "Alena"; if ($a = "Treehouse") { echo "Hello Alena, "; } echo "Welcome to Treehouse!"; ?>

The feedback given by the quiz is "Unfortunately, The value "Treehouse" is ASSIGNED to the variable $a INSTEAD of COMPARING $a to the string 'Treehouse'. Therefore the expression is evaluated as true."

I get that it's not a comparison. But it looks to me like $a is assigned to "Alena" and never reassigned. Isn't the conditional saying "IF it's true that $a = 'treehouse' (which it isnt) then perform the function, otherwise, dont, and simply echo 'welcome to treehouse'" ?

Ntokozo Ncube
Ntokozo Ncube
17,435 Points
Ntokozo Ncube
Ntokozo Ncube
17,435 Points

I m not fully getting your question but to compare use ==

2 Answers

Ntokozo Ncube
Ntokozo Ncube
17,435 Points
Ntokozo Ncube
Ntokozo Ncube
17,435 Points

I m not fully getting your question but to compare use ==

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Hi there, jough ! Let's take a look again at that code. This is a tricky one:

<?php 
     $a = "Alena"; 
     if ($a = "Treehouse") { 
        echo "Hello Alena, "; 
     } 
    echo "Welcome to Treehouse!"; 
?>

As you correctly pointed out, the = there is an assignment and not a comparison. It might not be immediately obvious, but when you do an assignment there is a boolean value returned. Now, this is where we get into the concept of "truthy" and "falsey". Here are some values that are considered "truthy": a non-empty string (which is the case here), a non-zero integer, a non-empty array. Here are some values that are considered "falsey": zero, an empty string, an empty array.

Because the value assigned was a non-empty string it is "truthy". This means that the assignment inside the if evaluates to true. But now, the value of $a has changed from "Alena" to "Treehouse".

Hope this clarifies things! :sparkles:

edited for additional clarification

You stated:

IF it's true that $a = 'treehouse' (which it isnt)

No, that would be what the comparison would say. What this is saying is "IF $a was assigned a "truthy" value" :smiley: