What does it mean to add a dot before and after a variable in php?

PHP is a popular server-side scripting language that is widely used in the field of web development. In PHP, you can often see a dot added before and after a variable. So what do these dots mean?

Adding a dot before and after the variable is actually an operator in PHP, called the concatenation operator. Its function is to concatenate two strings and generate a new string. For example:

$var1 = "Hello";
$var2 = "World";
$var3 = $var1 . $var2; // $var3现在的值是"HelloWorld"

In this example, the value of variable $var3 is concatenated by the strings in variables $var1 and $var2.

In addition to concatenating strings, the concatenation operator can also be used to concatenate arrays. For example:

$array1 = array("John", "Doe");
$array2 = array("Jane", "Smith");
$array3 = $array1 . $array2; // $array3现在的值是array("John", "Doe", "Jane", "Smith")

In this example, the array in variable $array3 is concatenated by the arrays in variables $array1 and $array2.

It should be noted that the connection operator can only be used to connect strings and arrays, and cannot be used to connect numbers or other types of data. Additionally, if one of the operands is null, the concatenation operator treats it as an empty string.

In addition to the connection operators with one dot before and after, PHP also provides a simpler way to connect strings, that is, using the .= operator. For example:

$var1 = "Hello";
$var2 = "World";
$var1 .= $var2; // $var1现在的值是"HelloWorld"

In this example, the value of variable $var1 is concatenated by the strings in variables $var1 and $var2. This method is more concise than the connection operator with one dot before and after. Clearly.

To sum up, adding a dot before and after a variable is a connection operator, and its function is to connect strings or arrays. When doing string concatenation, this can also be done using the .= operator. Mastering these basic string concatenation methods will help improve PHP programming efficiency and bring more convenience to Web development work.

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