返回true输出1,但返回false输出什么 [英] returning true outputs 1 but returning false outputs nothing
问题描述
这不是很重要,但我只是好奇,想知道其中的差别。
回声ISA(A); //输出1回声ISA(B); //输出什么。为什么没有输出0?
任何人都可以在这个问题上somelight棚?它似乎把我当成一个双重标准,当你从的角度看它是真输出作为1,但假不输出0。
再次没有什么大不了的,但我认为必须有PHP的理由来设计这样。明知可能给一些更深入地了解这个美丽的语言。
一个真正的价值将自己表现为一个可见的1,但假值不会。那么,告诉我什么是这种方法的优势在哪里?
例如功能我上面提到;
功能ISA($输入){
如果($输入==A):
返回true;
其他:
返回false;
万一;
}
一个布尔值TRUE将被转换为字符串1。布尔值FALSE为
转换为(空字符串)。这使得转换回来,
在布尔值和字符串之间。
块引用><一个href=\"http://us3.php.net/manual/en/language.types.string.php#language.types.string.casting\">http://us3.php.net/manual/en/language.types.string.php#language.types.string.casting
如果您想打印一个布尔值进行调试,您可以用var_dump或print_r的。
It's not very important but I was just curious to know the difference.
echo isA("A"); //outputs 1 echo isA("B"); //outputs nothing. why doesn't it output 0?
Anybody can shed somelight on this matter? It does seem to me as a double standard when you look at it from the point of view that "true" outputs as "1" but "false"does not output "0".
Again, no big deal but I think there must be a reason for PHP to be designed like that. Knowing that may give some more insight into this beautiful language.
A true value will manifest itself as a visible 1, but a false value won't. So, tell me what's the advantage of this method?
example function I referred above;
function isA($input){ if ( $input == "A" ): return true; else: return false; endif; }
解决方案A boolean TRUE value is converted to the string "1". Boolean FALSE is converted to "" (the empty string). This allows conversion back and forth between boolean and string values.
http://us3.php.net/manual/en/language.types.string.php#language.types.string.casting
If you want to print a boolean for debugging you can use var_dump or print_r.
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