Summarize object notes about attributes

Reply content: Refer to the PHP documentation: empty - Check whether a variable is empty. Obviously obj is not empty~Test it: print_r($obj); Game Object () is empty or non-empty. Don’t guess. Ah... the objects have been instantiated, so empty will definitely not be empty. What I understand is emptyempty(''); //true empty(0); //true empty('0'); //true empty(NULL); //true empty([]); //true empty(array(array())); //false $a;//Only definition and no assignment empty($a);//true class AA {} $aa = new AA(); emp

1. php empty is not an object without attributes and will return true?

Introduction: Tested: {code...}

2. PHP comparison operations and logic Operation

Introduction: PHP comparison operation and logical operation: 1. The following values ​​are judged as true using empty(): unassigned variables, undeclared variables, 0, "0", "", false, null, empty array array(), the value returned by the object's magic method __get(). In versions lower than PHP5.0, objects without any attributes are also judged as empty by empty. Note :empty() only accepts variables or the index value or attribute value of a variable. Constants cannot be passed in directly, nor operation expressions can be passed in. After PHP 5.5, expression 2 is supported, and is i

3. Detailed explanation of comparison operations and logical operations of PHP Camera Logic Logistic Regression Formal Logic

##Introduction: PHP, Logic: Detailed explanation of comparison operations and logical operations of PHP : 1. The following values ​​are judged as true using empty(): unassigned variables, undeclared variables, 0, "0", "", false, null, empty array array(), and the object's magic method __get() returns In versions lower than PHP5.0, objects without any attributes are also judged as true by empty. Note: empty() only accepts variables or index values ​​or attribute values ​​of variables. Constants cannot be passed in directly, nor can they be passed in. Operation expression, PHP 5.5 and later supports expression 2, is

4. eigendecomposition php empty checks whether a variable is empty

Introduction: eigendecomposition:eigendecomposition php empty Check whether a variable is empty: empty - Check whether a variable is empty Report a bug Description bool empty (mixed $var) If var is a non-empty or non-zero value, then empty () returns FALSE. In other words, "", 0, "0", NULL, FALSE, array(), var $var; and objects without any properties will be considered empty, and TRUE is returned if var is empty. Except that it does not occur when the variable is not set.

5. empty String exception prompts the difference between empty and isset

Introduction: empty String exception prompt: empty String exception prompt The difference between empty and isset: empty is to determine whether a variable is empty. If the variable is non-empty or non-zero, empty() returns FALSE. In other words, "", 0, "0", NULL, FALSE, array(), var $var, undefined; and objects without any attributes will be considered empty. If var is empty, TRUE will be returned. . (1) Number 0; (2) Empty character; (3) Variable defined as null; (4) Variable defined as false; (5) Empty array; (6) Undefined variable

6. When php detects whether a variable is set, can empty() replace isset()? _PHP Tutorial

#Introduction: When PHP detects whether a variable is set, can empty() replace isset()? . Let’s review empty and isset empty first. Check whether a variable is empty, 0, 0, NULL, FALSE, array(), var $var; and objects without any attributes will be considered empty, such as

7. The difference between empty() and isset() in PHP

Introduction: 1. Purpose of empty function: detect variables Empty judgment: If var is a non-empty or non-zero value, empty() returns FALSE. In other words, "", 0, "0", NULL, FALSE, array(), var $var; and objects without any properties will be considered empty if...

8. The difference between empty, isset and is_null in PHP

Introduction: The difference between empty, isset and is_null in PHP empty() returns FALSE if variable is a non-empty or non-zero value. In other words, "", 0, "0", NULL, FALSE, array(), var $var, undefined; and objects without any properties will be considered empty, and TRUE will be returned if var is empty . isset returns

9 if the variable exists (not NULL). PHP’s empty function that is easily used abnormally

Introduction: PHP’s empty function is easily used incorrectly ? In the official manual of php it is written, ? Checks whether a variable is empty. If var is a non-empty or non-zero value, empty() returns FALSE. In other words, "", 0, "0", NULL, FALSE, array(), var $var; and objects without any properties will be considered empty, and TRUE is returned if var is empty. ? ? Then in his hands

10. empty function that is easily used abnormally

Introduction: php is prone to errors The empty function used is written in the official manual of PHP to check whether a variable is empty. empty() returns FALSE if var is a non-empty or non-zero value. In other words, "", 0, "0", NULL, FALSE, array(), var $var; and objects without any properties will be considered empty, and TRUE is returned if var is empty. ??Then he solemnly explained in his manual

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#php empty is not an object without attributes and will return true?

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