Is there a way to test if a string/char is numeric

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martin.j asked Aug 22, '22 Jordan Johnson answered Aug 22, '22

Is there a way to test if a string/char is numeric

I have been looking for a way to test if a string or character is a digit or alphanumeric value. In most programming languages there is a function called IsDigit, IsNumeric or something similar, but I cant find that feature in flexscript.

I can use the stringtonum or .tonum methods, but since they always return 0 which is a numeric value rather than NULL, that is rather unhelpfull and a bit of an error in my opinion. You cant tell if the character you converted was actually a 0 or any other character that isnt numeric.

This would be rather usefull when trying to rename autogenerated objects that automatically get a number at the end of their name. I want to find out how many characters the numer at the end of the name is and then replace it with a code of my own choosing.

Software Version:

FlexSim 22.2.0

string conversion isdigit isnumeric

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Answer 1 · 2022-08-22T15:55:34Z

Jordan Johnson answered Aug 22, '22

If you want to split text from a number, I'd do that with a regex:

string name = "Processor23";
var matches = name.match(/(.*[^\d])(\d+)$/);
Array parts;
while ((parts = matches.findNextMatch()).length) {
  print("whole match:", parts[1]);
  print("name:", parts[2]);
  print("number:", parts[3]);
}

I often use https://regex101.com/ to help me get the regex right.

If you use code like the code above, you can strip off the number from the name part, and then combine the name with some other value.

As far as generally testing a string to see if it is a number, I'd probably use code like this:

string test = "123.4";
if (test.match(/^[+-]?([0-9]*[.])?[0-9]+$/).length) {
  return "isNumber";
} else {
  return "not a number";
}

You could improve this regex to include scientific notation, if needed.

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Answer 2 · 2022-08-22T13:15:10Z

Lars Jacobsen answered Aug 22, '22 Felix Möhlmann commented Aug 22, '22

A possibility is to cast the string in question to a Variant. That provides some opportunities for testing the datatype. See Variant Doc

Example code

1661174081057.png (9.4 KiB)

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Felix Möhlmann commented · Aug 22, 2022 at 02:53 PM

If the string only consists of ASCII characters, you can check each one by comparing it to the relevant range of ASCII indexes with the [] operator.

if(str[i] >= 48 && test[i] <= 57)
{
    // char is numerical
}

For the purpose of removing/replacing numbers in an autogenerated name, the replace() method could be useful.

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