How does PHP compare strings with comparison operators?

php string compare operators type-coercion

Shakti Singh · Oct 15, 2012 · Viewed 10.3k times · Source

I'm comparing strings with comparison operators.

I needs some short of explanations for the below two comparisons and their result.

if('ai' > 'i')
{
    echo 'Yes';
}
else
{
    echo 'No';
}

output: No

Why do these output this way?

if('ia' > 'i')
{
    echo 'Yes';
}
else
{
    echo 'No';
}

Output: Yes

Again, why?

Maybe I forgot some basics, but I really need some explanation of these comparison examples to understand this output.

Answer

PHP will compare alpha strings using the greater than and less than comparison operators based upon alphabetical order.

In the first example, ai comes before i in alphabetical order so the test of > (greater than) is false - earlier in the order is considered 'less than' rather than 'greater than'.
In the second example, ia comes after i alphabetical order so the test of > (greater than) is true - later in the order being considered 'greater than'.