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- Synopsis:
- $isalpha(<text>)
- $isdigit(<text>)
- $isnumber(<text> <base>>)
-
- Technical:
- These function test whether the first character in the given string is
- an alphabetical character or a digit. Only the first character is
- tested.
-
- The function $isnumber() is very similar to $isdigit(), except that
- it takes two arguments, the second specifying the numeric base of <text>.
- The second argument must be prefixed with a 'b'; eg. "b8" for base 8, "b16"
- for base 16. And as always, numbers in base 16 may be prefixed with "0x".
-
- Practical:
- These functions are useful for testing an input string to see whether it
- is a number or a text string. One use for this might be to check if it
- would be suitable input for $iptoname() or $nametoip(). Keep in mind
- that only the first character is tested, so this isn't a reliable way
- to see if the entire string is a number.
-
- Returns:
- "true" or "false" value if first character is a letter or a digit
-
- Examples:
- $isalpha(hello) returns true
- $isalpha(2hello) returns false
- $isdigit(123) returns true
- $isdigit(2abc) returns true
- $isdigit(a123) returns false
- $isnumber(0x9FF b16) returns true
-
-