Use of braces (curly braces {}) in PHP

Use of braces (curly braces {}) in PHP

There are basically three cases of using braces in php. The following article summarizes these three cases.

I. function name () {}, for () {} and so on. I will not talk about this situation, but I also know what it is.

2. $ str {4} is followed by the braces ({}) or brackets ([]) after the variable of the string. Enter a number. Here is the string variable as an array. For example:

<? Php $ str = 'phpernote. com '; echo $ str {0}; // output pecho $ str [1]; // output h $ str = '000 '; $ str {0} = '1'; echo $ str; // output 100

Note: This feature can be used to check whether the length of a string is sufficient. The strlen function is replaced by isset because isset is a language structure and strlen is a function, therefore, using isset is more efficient than using strlen. For example, to determine whether the length of a string is less than 5, see the following:

If (! Isset ($ str {5}) is better than if (strlen ($ str) <5.

3. Use braces for variable variables, such as {$ val}. In this case, braces tell PHP that the enclosed parts should be processed as variables. Example:

<? Php $ array = array ('www ', 'name' => 'phpernote', 'com'); echo "$ array ['name']"; // The syntax error echo "{$ array ['name']}" will be reported using this sentence; // This sentence is normal, and the characters in braces are processed as variables.

Note: $ {$ a [1]} and $ {$ a} [1] are completely different:

$ {$ A [1]} $ a [1] is a variable;

$ {$ A} [1] $ a is a variable;

The advantage of this method is that when a variable is referenced in a string, you can avoid using the. Operator to reduce the input of code.