PHP variable Under what circumstances braces {}

Such as:
$sql = "INSERT into article (' channel_id ', ' title ', ' Detail ', ' pub_time ') values (' {$cid} ', ' {$title} ', ' {$detail} ', ' {$ Time} '); ";

What does it mean to add {}?
And why do you include the field name?

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Best Answer

The meaning of the PHP variable placed in curly braces

2. //The following is okay as it ' s inside a string. Constants is not
4. //looked for within strings so no E_notice error here
6. print "Hello $arr [fruit]"; //Hello Apple
8.      
10. //With one exception, braces surrounding arrays within strings
12. //allows constants to being looked for
14. Print "Hello {$arr [fruit]}"; //Hello carrot
16. Print "Hello {$arr [' Fruit ']}"; //Hello Apple

Here are some explanations for why:

1. Represents a variable inside {}, which is handled by variable when executed
2. Refer to the special inclusion of variables in a string, so that you can reduce the amount of code input by not using the. operator.

In fact, the output of the block is equivalent to print "Hello". $arr [' fruit '];

PHP: The role of curly braces (curly braces {}) in string variables

The PHP variable is appended with a curly brace {}, which is filled with numbers, which refers to the character of the corresponding ordinal of the PHP variable.
For example:
$str = ' Hello ';
echo $str {0}; Output is H
echo $str {1}; Output to E
If you want to check how much length a string satisfies, consider replacing the strlen function with this curly brace (curly brace) and isset, because Isset is a language structure and strlen is a function, so using isset is more efficient than using strlen.
For example, determine whether a string is less than 5 in length:
if (!isset ($str {5})) is better than if (strlen ($STR) < 5).

PHP variable Under what circumstances braces {}