isset syntax

What is the difference between isset and is_null? in the manual, the functions of isset and is_null are almost the same .. is isset the opposite alias of is_null? Well, there are many differences ~ Everything is different because: is_null... "> What

PHP determines whether an array of key values exists, using empty or isset or array_key_existsPurpose of this articleThe first few days of work, it is necessary to frequently judge the existence of the key values in the array, initially using the

Isset is a statement. like echo and print, isset is a language structure of PHP, while is_null is a function. it can be called as a variable function, just like a common function. What is the difference between isset and is_null,In the manual, isset

Isset is a statement. like echo and print, isset is a language structure of PHP, while is_null is a function. it can be called as a variable function, just like a common function. What is the difference between isset and is_null,In the manual, isset

[PHP Source Code Reading] empty and isset functions, emptyisset Recently, I was asked how to judge variables when using empty and isset functions in PHP. At the beginning, I was very frustrated, because I was just a bit confused, in order to

PHP Performance Optimizations: Use Isset () to determine string length faster than strlen () How to determine the length of a string in PHP? The first thing many people think about is strlen () Mb_strlen () these functions. But in terms of program

Many programmers like to use strlen () Mb_strlen () These functions when judging the length of a string, although they have always been a professional test string length, but they do not know Strlen () Mb_strlen () These functions are not optimal.

Php performance optimization: using isset () to determine the string length is faster than strlen. How can I determine the length of a string in php? Many people think of strlen () mb_strlen () functions first. However, in terms of program

PHP source code reading: the empty and isset functions have recently been asked how to judge the variables when the empty and isset functions are in PHP. at first, I was overwhelmed, because I was just a bit confused, in order to understand its true

How can I determine the length of a string in php? Many people think of strlen () mb_strlen () functions first. However, in terms of program performance, these two functions are not optimal in determining the length of a string, although they are