Question

PHP文档中的类型comparison chart显示了严格===和松散==比较的结果。没有关于不平等比较的事情：

true < 0 => false
0 < true => true
true < 1 => false
1 < true => false
true < -1 => false
-1 < true => false

false < 0 => false
0 < false => false
false < 1 => true
1 < false => false
false < -1 => true
-1 < false => false

有人可以合理化上述结果吗？

Answer 1

将布尔值转换为整数时，true将转换为1，false将转换为0

来自PHP手册：http://php.net/manual/en/language.types.integer.php

来自布尔值

FALSE将产生0（零），而TRUE将产生1（一）。

另外：

-1被视为TRUE，与任何其他非零（无论是负数还是正数）一样！

true  < 0 => false => true < (bool)(0) => true < false => 1 < 0 = false
0 < true => true  => (bool)(0) < true => false < true => 0 < 1 = true
true < 1 => false => true < (bool)(1) => true < true => 1 < 1 = false
1 < true => false => (bool)(1) < true => => true < true => 1 < 1 = false
true < -1 => false => true < (bool)(-1) => true < true => 1 < 1 = false
-1 < true => false => (bool)(-1) < true => true < true = > 1 < 1 = false

false < 0 => false => false < (bool)(0) => false < false => 0 < 0 = false
0 < false => false => (bool)(0) < false => false < false => 0 < 0 = false
false < 1 => true => false < (bool)(1) => false < true => 0 < 1 = true
1 < false => false => (bool)(1) < false => true < false => 1 < 0 = false
false < -1 => true => false < (bool)(-1) => false < true => 0 < 1 = true
-1 < false => false => (bool)(-1) <  false => true < false => 1 < 0 =  false

Answer 2

true＆lt; 0 =＆gt; false ===＆gt; 1＆lt; 0 =＆gt; false（0 == 0 ==＆gt; true）
0＆lt; true =＆gt;是= =＆gt; 0＆lt; 1 =＆gt;真正
真实＆lt; 1 =＆gt; false ===＆gt; 1＆lt; 1 =＆gt; false（1 == 1 ==＆gt; true）
1＆lt; true =＆gt; false ===＆gt; 1＆lt; 1 =＆gt; false（1 == 1 ==＆gt; true）
真实＆lt; -1 =＆gt; false ===＆gt; 1＆lt; -1 =＆gt;假
-1＆lt; true =＆gt; false ===＆gt; -1＆lt; 1 =＆gt; false ======＆gt; 1＆lt; 1 =＆gt; false（布尔类型被视为无符号）
===＆GT; 假＆lt; 0 =＆gt; false ===＆gt; 0＆lt; 0 =＆gt;假
0＆lt; false =＆gt; false ===＆gt; 0＆lt; 0 =＆gt;假
假＆lt; 1 =＆gt;是= =＆gt; 0＆lt; 1 =＆gt;真正
1＆lt; false =＆gt; false ===＆gt; 1＆lt; 0 =＆gt;假
假＆lt; -1 =＆gt;是= =＆gt; 0＆lt; -1 =＆gt;是======＆gt; 0＆lt; 1 =＆gt; true（布尔类型被视为无符号）
-1＆lt; false =＆gt; false ===＆gt; -1＆lt; 0 =＆gt; false ======＆gt; 1＆lt; 0 =＆GT; false（布尔类型被视为无符号）

理解数字和布尔值之间的不等式比较

2 个答案: