（$ LogIncrease == true）始终求值为true

Question

I have just installed the latest version of LAMP on Debian 7.0.0.

For some reason, the following code

    if ($LogIncrease==true) echo "true" . "<br\>";
    else echo "false" . "<br\>";
    echo "LogIncrease=" . $LogIncrease . "<br\>";

returns

true
LogIncrease=false

when $LogIncrease is actually false and

true
LogIncrease=true

when $LogIncrease is actually true

When I use

    if ($LogIncrease===true) echo "true" . "<br\>";
    else echo "false" . "<br\>";

I always get false. Could someone tell me what is wrong with the way I am using the conditional statement?

Answer 1

This is probably* happening because $LogIncrease is string "false" versus the boolean false.

According to the documentation, only the following are converted to boolean false:

When converting to boolean, the following values are considered FALSE:

• the boolean FALSE itself
• the integer 0 (zero)
• the float 0.0 (zero)
• the empty string, and the string "0"
• an array with zero elements
• an object with zero member variables (PHP 4 only)
• the special type NULL (including unset variables)
• SimpleXML objects created from empty tags

The string "false" doesn't evaluate to false. In other words, "false" == true.

Therefore, if var_dump($LogIncrease) outputs the following:

string(5) "false"

It is normal that your condition is evaluated as true.

^{* Saying probably here because I do not have enough information from your snippet of code to be sure.}