Comparing two strings in which one starts with a zero

Question

I wanted to check two strings with each other, one which starts with a zero and one without. But this seems to result in a true. An example:

if("098" == "98"){
   return true;
}

Can somebody explain why this statement results to true with PHP?

if you add === it implies strict checking and it should be false — Rotimi, Mar 30 '17 at 09:39
Yes that works but I was wondering why == won't work. Thanks for your comment. — Nuri Ensing, Mar 30 '17 at 09:40

score 1 · Accepted Answer · answered Mar 30 '17 at 09:43

The simple reason i can think of is that The operator == casts between two different types if they are different, while the === operator performs a 'typesafe comparison'. That means that it will only return true if both operands have the same type and the same value.

So from your example,

if("098" == "98"){
   //true
}

Also a couple of PHP functions also have parameters to imply strict checking. An example is in_array

score 1 · Answer 2 · answered Mar 30 '17 at 09:44

if you compare with ==, php tries to compare them without respecting the type. So what actually happens, php converts the two numbers to an integer, and as 98 is equal to 98, "098" == "98" is also true.

The best way to avoid this is, use ===, which compares also the type without any conversions.

if("098" === "98"){
    return true;
}

Comparing two strings in which one starts with a zero

2 Answers2