Nice to meet you. I'm Koizumi from the Development Department.
\nIn this article, I will explain how to make 0-10 without using numbers in PHP.
\n <\/p>\n
PHP. \n1. type must be int (confirmed by var_dump) If you know PHP, please try to predict what the code will be. I indicated at the beginning <\/p>\n 2 is not 1+1, but the bitwise negation operator <\/p>\n Speaking of 3, Pi. <\/p>\necho true<\/code> will output \"1\".
\nIt occurred to me that I could use this to create other numbers without using any numbers at all, so I tried it out.
\nIt's not interesting to just make one, so I added the following restrictions.<\/p>\n
\n2. be as short as possible
\n3. don't use constants (because it's too easy)\n<\/p>\n
\nIf you want to test whether the code in the text is correct, you can easily try it by copying and pasting it into the following site.
\n\u21d2https:\/\/3v4l.org\/<\/a><\/p>\n1 and 0<\/h2>\n
echo true<\/code> looks like 1, but internally it is of type bool.
\nYou'll need to cast it to an int, but you can use the commonly-usedintval()<\/code>is long, so the operator + is used.
\nAlso, \"true\" is 4 characters long, so you can shorten it to 3 characters by adding \"(empty string)\" and \"! to shorten it to 3 characters.
\nYou can create false as well and cast it to int to create 0 as well.
\nThe result is the following code.<\/p>\nvar_dump(+!'') ; \/\/0\r\nvar_dump(+!'') ; \/\/1\r\n<\/pre>\n
Bit negation(2)<\/h2>\n
~<\/code>to make it.
\nIt's complicated, so I won't explain it, but bitwise negating an integer n results in -(n+1). (If you are curious, please look it up in 2's complement)
\nThe sign can be reversed by adding a -, so-~<\/code>can \"cast a positive number to an int and add one\".
\nThis is a frequent technique, so please keep it in mind.<\/p>\nvar_dump(-~+!'') ; \/\/2\r\n<\/pre>\n
Pi (3 to 5)<\/h2>\n
pi()<\/code>I know. As it is, it is a float type and becomes 3.14... so cast it to int.
\nThe bitwise operators will cast to int, so~~<\/code>You can truncate by putting two bit negations in a row, such as
\nBy combining pi and bit negation, we can make 3 to 5.<\/p>\nvar_dump(~~pi()); \/\/3\r\nvar_dump(-~pi()); \/\/4\r\nvar_dump(-~-~pi()); \/\/5\r\n<\/pre>\n
Bit shift (6 to 9)<\/h2>\n