Validating numeric values in c
Useful to state these odd cases, for when you see code that checks for an empty string and is_numeric, you can tell it's a waste of a comparison. is_numeric will also return true if the number begins with a decimal point and/or a space, provided a number follows (rather than a letter or punctuation). All of the following are valid numbers to is_numeric():- 1- 1.123- 0x FF- 0123.45e6See the problem?So, it doesn't necessarily have to start with a digit. If we really want just an integer, this function is too broad."Source: Be careful when using is_numeric() to escape SQL strings. - no Referring to previous post "Be aware if you use is_numeric() or is_float() after using set_locale(LC_ALL,'lang') or set_locale(LC_NUMERIC,'lang')": This is totally wrong!PHP interprets 0123 without quotes as a literal octal number; but SQL just throws a syntax error. Anything greater than approximately 1.8e308 is too large for a double, so it becomes infinity, i.e. What that means is that, for each string with more than 308 characters, is_numeric() will return FALSE, even if all chars are digits.
Folglich ist '42' ist numerisch '1337' ist numerisch '1337' ist numerisch '1337' ist numerisch '1337' ist numerisch '1337' ist numerisch 'not numeric' ist NICHT numerisch ' Array' ist NICHT numerisch '9.1' ist numerisch The above script will output:bool(true)So this function is not intimidated by super-big numbers. PS: Also note that if you write is_numeric (45thg), this will generate a parse error (since the parameter is not enclosed between apostrophes or double quotes). The documentation does not clarify what happens if you the input is an empty string - it correctly returns false in my experience. However the problem with is_numeric() isn't that it can't detect an integer, it is that it detects a lot more than just integers.Regarding renimar at yahoo's function to yield ordinal numbers, the function lacks one thing.It accounts for numbers in the teens only if the number is below 100. adjustments: i'm sure this still isn't optimal, but it should also cover japanese-style numerals and it fixed a couple of other issues with the other regexen. also nadim's regexen are slightly suboptimal at one point having an unescaped '.' operator, and the whole thing could easily be combined into a single regex (speed and all).
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Please note that this function will work properly unless the user fat fingers an extra decimal in the wrong place. american numeral notations, it should be noted that at least in japanese, numbers aren't grouped with an extra symbol every three digits, but rather every four digits (for example 1,0000 instead of 10.000).