In_array (' "", Array (' 1 ')) Why return True

echo in_array('01',array('1'))

When using In_array not to use strict, why return 1, how to judge?

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echo in_array('01',array('1'))

When using In_array not to use strict, why return 1, how to judge?

In_array ($needle, $haystack)-checks if a value exists in the array

You can understand that by taking the values in the array sequentially, and then comparing them with the $needle. Returns true if = = is determined. Pseudo-code like:

function in_array($needle, $haystack) {    foreach($haystack as $val) {        if ($val == $needle) {            return true;        }    }    return false;}

Note: the difference between = = = = = = In PHP.

var_dump(("01" == 1));var_dump((" 1 " == 1));

And then you get it.

Add:

In the case of landlord problem, in_array the input string "01" When judging whether the string and the number are equal. Details can be found in: PHP type comparison table-PHP official website php.net

• '01' == '1';The result is TRUE
• echo TRUEThe result is 1.

Attach a "PHP type comparison table" http://php.net/manual/zh/types.comparisons.php

in_arrayThe source code is defined in HTTPS://GITHUB.COM/PHP/PHP-SRC/BLOB/MASTER/EXT/STANDARD/ARRAY.C

/* {{{ proto bool in_array(mixed needle, array haystack [, bool strict])   Checks if the given value exists in the array */PHP_FUNCTION(in_array){    php_search_array(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);}/* }}} */

Continue to search php_search_array the source code, when using non-strict mode, call the fast_equal_check_function function, with the help of GitHub search function, quickly navigate to the Zend/zend_operators.h file

static zend_always_inline int fast_equal_check_function (zval *result, Zval *op1, Zval *op2 tsrmls_dc) {if (EXPECTED (Z_T Ype_p (OP1) = = Is_long)) {if (Expected (z_type_p (OP2) = = Is_long)) {return z_lval_p (OP1) = = Z_lval_p (op2        );        } else if (Expected (z_type_p (OP2) = = is_double)) {return (DOUBLE) z_lval_p (OP1)) = = Z_dval_p (OP2); }} else if (Expected (z_type_p (OP1) = = is_double)) {if (expected (z_type_p) = = Op2)) {is_double        RN z_dval_p (OP1) = = Z_dval_p (OP2);        } else if (Expected (z_type_p (OP2) = = Is_long)) {return z_dval_p (OP1) = = ((double) z_lval_p (OP2)); }} else if (Expected (z_type_p (OP1) = = is_string)) {if (expected (z_type_p) = = OP2)) {if (            Z_str_p (OP1) = = Z_str_p (OP2)) {return 1; } else if (z_strval_p (OP1) [0] > ' 9 ' | | Z_strval_p (OP2) [0] > ' 9 ') {if (Z_strlen_p (OP1)! = Z_strlen_p (OP2)) {return 0;                } else {return memcmp (z_strval_p (OP1), z_strval_p (OP2), Z_strlen_p (OP1)) = = 0;                }} else {zendi_smart_strcmp (result, OP1, OP2);            return z_lval_p (Result) = = 0;    }}} compare_function (result, OP1, OP2 tsrmls_cc); return z_lval_p (Result) = = 0;}

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