This question already has answers here:
Understanding PHP type coercion
(4 answers)
Closed 7 years ago.
Why does this code echo Yes. even though variables are not equal!
$a = '0e462097431906509019562988736854';
$b = '0e830400451993494058024219903391';
if( $a == $b ) echo 'Yes.';
else echo 'No!';
Both will treated as numbers, and PHP had limitations in number storage before.
So check that.
Try to use '==='. it will check the type also, so those will not convert to numbers.
Refer this question and its answers.
You want strcmp, not the equality operator.
try it, with using strcmp function:
if(int strcmp ($a,$b)===0) echo 'Yes.';
else echo 'No!';
Try using '===' instead of '=='.
'==' has a "weaker" comparison because it does not check for type.
'===' on the other hand, checks for the type as well, and it is generally good practice to be more explicit when you compare two things.
Related
This question already has answers here:
Comparing String to Integer gives strange results
(5 answers)
How does PHP compare strings with comparison operators?
(4 answers)
Closed 3 years ago.
This is my code
$preference = '151000';
$range = 'above';
if($preference <= $range){
echo "Yes"; die;
}else{
echo "No"; die;
}
This provides 'Yes', i want to know why.
You can see it in the php manual. https://www.php.net/manual/en/language.operators.comparison.php
When comparing a string, number or resource with another string, number or resource:
Translate strings and resources to numbers, usual math
Btw: '151000' is a string, not a number. 15100 would be a number.
Here you basically compare two strings and php uses their ASCII codes to compare them. The first symbol 1 is lower than 'a'.
If you want to compare two strings properly, use function:
strcmp()
If you want compare different types, you can read about PHP type comparison tables.
If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically.
Read more here.
This question already has answers here:
Why does PHP consider 0 to be equal to a string?
(9 answers)
Closed 8 years ago.
When I run the follow code in PHP
if('yes' == 0)
echo 'a';
else
echo 'b';
The output is a.
I don't understand what happen?
And can I convert the php code to C source code to have a look what real happening?
PHP is a dynamically typed language, and == is a loose comparison operator, meaning it will first cast values it compares to one type, int for that matter, and then compare them; strings are being cast to integers by taking numericals from the left part, so 1abc casts to 1. By that logic yes cast to 0, and 0 == 0 yields true.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
The 3 different equals
Can anyone tell me why, when using the code below, I am getting redirected to elephant.com rather than seeing a 'giraffe!
<?php
$foo="giraffe";
if($foo="elephant"){
header("location:http://www.elephant.com");
exit();
}else{
echo $foo;}
?>
Thanks for looking
J
if($foo="elephant")
You're assigning $foo here, rather than comparing it; you should be doing:
if($foo=="elephant")
The result of an assignment operation is the value that's just been assigned; in this case, 'elephant' is evaluating to true.
Your if() statement has a single equal sign. This doesn't do a comparison in PHP; it sets the value and returns true.
In order to do a comparison, you need to use either a double-equal or a triple-equal sign:
if($foo == "elephant") { .... }
or
if($foo === "elephant") { .... }
The difference between the two is that double-equal doesn't care about the variable's data type, whereas triple-equal does. In this case, there's not much difference between them, but it's worth learning and understanding the differences because they can bite you if you don't know them. More info here: http://php.net/manual/en/language.operators.comparison.php
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Why does PHP consider 0 to be equal to a string?
php string comparasion to 0 integer returns true?
it seems that as one has in PHP an if-statement where a function some_function() returns zero
<?php
if( some_function() == "whatever_you_want" ) { ... }
the statement will always be executed since
<?php
echo some_function() == "whatever_you_want";
is then TRUE.
Why behaves PHP in such a counter intuitive way?
This is a defined behavior of PHP when you compare a number value and a string value:
If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically. These rules also apply to the switch statement. The type conversion does not take place when the comparison is === or !== as this involves comparing the type as well as the value.
Use strict value comparison with === or !== and you’re getting the expected result.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Javascript === vs == : Does it matter which “equal” operator I use?
Not really relative to any type of code, just in general?
usually === also represents equality of type.
so:
1 == "1" //true
1 === "1" //false
=== is the identical operator; it returns true when both the value and the type of the two operands are the same. == is the equal operator; it does not check types, just values.
Read more here.
=== compares the value as well as type of variable
== doesn't compare type