The effect of adding braces {} to output variables in PHP_PHP Tutorial

 　　php输出变量加大括号,这是什么写法?看下面一段代码：

代码如下	复制代码
代码如下	复制代码
header("Content-Type:text/html; charset=utf-8"); $test="1变量1"; //echo "前面有字符串aa ".$test." bb后面字符串"; echo "前面有字符串aa {$test} bb后面字符串"; ?>

header("Content-Type:text/html; charset=utf-8");

$test="1变量1";

//echo "前面有字符串aa ".$test." bb后面字符串";

echo "前面有字符串aa {$test} bb后面字符串";

?>

It can be seen that the effect of adding braces to PHP output variables is the same as using the . operator to output variable strings. The following three points are summarized to help understand the role of adding braces {} to PHP output variables:

1. Indicates that the value inside {} is a variable and will be processed according to the variable during execution;

2. The special inclusion method used to reference variables in a string, so that the . operator can be used without using it, thereby reducing the amount of code input;

　3. Prevent the variable name from being concatenated with the following string.

Attachment:

The role of braces {} in string variables:

Add a brace {} after the PHP variable and fill in the numbers, which refers to the characters corresponding to the corresponding serial numbers of the PHP variable.

For example:

The code is as follows

$str = 'hello';
echo $str{0}; // The output is h
echo $str{1}; // The output is e

代码如下
$str = 'hello'; echo $str{0}; // 输出为 h echo $str{1}; // 输出为 e

If you want to check whether a string meets a certain length, you can consider using braces {} plus isset to replace the strlen function. Because isset is a language structure and strlen is a function, using isset is more efficient than using strlen. high.

For example, to determine whether the length of a string is less than 5:

The code is as follows

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

代码如下
if ( !isset ( $str{5} ) ) 就比 if ( strlen ( $str ) < 5 ) 好。

http://www.bkjia.com/PHPjc/372084.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/372084.htmlTechArticlephp output variables are enclosed in curly brackets. What is the writing method? Look at the following code: Copy the code as follows? php header (Content-Type: text/html; charset=utf-8); $test=1 variable 1; //echo is preceded by...