Php assignment and reference assignment instructions _ PHP Tutorial

Php assignment and reference assignment instructions. In php, values are assigned to variables and references. next I will introduce some of their basic usage and differences. 1. value assignment: Copy the value of the value assignment expression to the variable. In php, values are assigned to variables and references. next I will introduce some of their basic usage and differences.

1. value assignment: Copy the value of the value assignment expression to the variable. Example:

The code is as follows:
$ Number = 15; $ Age = 20; $ Sum = 12 + "15"; // $ sum = 27

2. there are two ways to create an array: variable assignment and function call. here we will first talk about the former.

You can assign values to an array variable directly.

Instance:

The code is as follows:
$ Lang [] = "php "; $ Lang [] = "html "; $ Lang [] = "css "; Echo "$ lang [0] "; Echo "$ lang [1] "; Echo "$ lang [2] "; ?>

Array content generated by the three assignment statements:

0 => php

1 => html

2 => css

3. reference value assignment: the created variable is the same as that referenced by another variable. Therefore, if multiple variables reference the same content and modify any of the variables, the other variables will be reflected. Add an & symbol ($ val2 = & $ val1) after the equal sign to complete the reference assignment or put the & symbol before the referenced variable ($ val2 = & $ val1 ):

The code is as follows:
$ Val1 = "hello "; $ Val2 = & $ val1; $ Val2 = "goodby "; Echo '$ val1 is'. $ val1 ." "; Echo '$ val2 is'. $ val2 ." "; ?> $ Val1 is goodby $ Val2 is goodby

Foreach reference assignment

Code:

The code is as follows:
$ A = array ( 'A' => 'A ', 'B' => 'BB ', 'C' => 'CC ', ); Foreach ($ a as & $ v ){ ; } Print_r ($ ); Foreach ($ a as $ v ){ } Print_r ($ );

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If you think about it, it is actually a simple reference. after foreach is completed for the first time, $ v is actually a reference of $ a ['c']. during The Loop, each value assigned to $ v changes the value of $ a ['c']. the last value assigned to $ v is $ v = $ a ['c']. $ a ['c'] is assigned $ a ['B'] for the last time.

Bytes. 1. value assignment: Copy the value of the value assignment expression to the variable ....