在PHP中评估三元运算符

Question

echo strlen('Hello World') > 2 ? '...' : '' . substr('Hello World',0,2);

above code output:

...

what I except was

...He

Can anyone explain how the above code is evaluated in php

EDIT

echo substr('Hello World',0,2) . strlen('Hello World') > 2 ? '...' : '';

OUTPUT

NO OUTPUT

BUT this works

echo substr('Hello World',0,2), strlen('Hello World') > 2 ? '...' : '';

OUTPUT

He...

Answer 1

It's evaluated like this:

echo strlen('Hello World') > 2 ? '...' : ('' . substr('Hello World',0,2));

What you probably want is this:

echo (strlen('Hello World') > 2 ? '...' : '') . substr('Hello World',0,2);