Note that using Incrementing/Decrementing operators on string is legal
<?php
$str = "";
echo ++$str; // output: 1
?>
New E_WARNING and E_NOTICE errors
have been introduced when invalid strings are coerced using operators
expecting numbers (+ -
* / **
% << >>
| & ^) or their
assignment equivalents. An E_NOTICE is emitted when the
string begins with a numeric value but contains trailing non-numeric
characters, and an E_WARNING is emitted when the string
does not contain a numeric value.
<?php
'1b' + 'something';
以上例程会输出：
Notice: A non well formed numeric value encountered in %s on line %d Warning: A non-numeric value encountered in %s on line %d
Previously, 3-octet octal string escape sequences would overflow silently.
Now, they will still overflow, but E_WARNING will be
emitted.
<?php
var_dump("\500");
以上例程会输出：
Warning: Octal escape sequence overflow \500 is greater than \377 in %s on line %d string(1) "@"
$this 不一致的修正
Whilst $this is considered a special variable in PHP, it
lacked proper checks to ensure it wasn't used as a variable name or
reassigned. This has now been rectified to ensure that
$this cannot be a user-defined variable, reassigned to a
different value, or be globalised.
Session ID 将不再在生成时进行哈希。这一变化，会导致以下四个 ini 设置不再使用：
session.entropy_file
session.entropy_length
session.hash_function
session.hash_bits_per_character
并增加以下两个 ini 设置：
session.sid_length - 定义会话 ID 的长度（为了向后兼容，默认为 32 个字符）
session.sid_bits_per_character - 定义了每个字符的存储位数（即增加了会话
ID 中可使用的字符范围），为了向后兼容，默认为 4
precisionIf the value is set to -1, then the dtoa mode 0 is used. The default value is still 14.
serialize_precisionIf the value is set to -1, then the dtoa mode 0 is used. The value -1 is now used by default.
gd.jpeg_ignore_warningThe default of this php.ini setting has been changed to 1, so by default libjpeg warnings are ignored.
opcache.enable_cliThe default of this php.ini setting has been changed to 1 (enabled) in PHP 7.1.2, and back to 0 (disabled) in PHP 7.1.7.
Session IDs will now only be generated with a CSPRNG.
null is allowed
TypeError exceptions for arg_info type checks will
now provide more informative error messages. If the parameter type or return
type accepts null (by either having a default value of null or being a
nullable type), then the error message will now mention this with a message
of "must be ... or null" or "must ... or be null."
Note that using Incrementing/Decrementing operators on string is legal
<?php
$str = "";
echo ++$str; // output: 1
?>