In PowerShell how can I test if a variable holds a numeric value

Question

In PowerShell  how can I test if a variable holds a numeric value   Currently  I m trying to do it like this  but it always seems to return false   add-type -Language CSharpVersion3        public class Helpers           public static bool IsNumeric object o                return o is byte     o is short     o is int     o is long                    o is sbyte    o is ushort    o is uint    o is ulong                    o is float    o is double    o is decimal                                       filter isNumeric  InputObject         Helpers   IsNumeric  InputObject     PS gt  1   isNumeric False

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If you are testing a string for a numeric value then you can use the a regular expression and the -match comparison  Otherwise Christian s answer is a good solution for type checking   function Is-Numeric   Value        return  Value -match     d          Is-Numeric 1 23 True Is-Numeric 123 True Is-Numeric    False Is-Numeric  asdf123  False

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You can do something like     testvar -match    0-9       or   testvar -match    d      Returns True if  testvar is a number

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Each numeric type has its own value  See TypeCode enum definition  https   docs microsoft com en-us dotnet api system typecode view netframework-4 8 Based on this info  all your numeric type-values are in the range from 5 to 15  This means  you can write the condition-check like this   typeValue    x getTypeCode   value   if   typeValue -ge 5 -and  typeValue -le 15    quot x has a numeric type  quot

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Testing if a value is numeric or a string representation of a numeric value   function Test-Number        Param                Parameter Mandatory  true                     Position 0            ValidatePattern     d                  Number             Number -is  ValueType  -or  Double   TryParse  Number  ref  null      Testing if a value is numeric   function Test-Number        Param                Parameter Mandatory  true                     Position 0            ValidatePattern     d                  Number             Number -is  ValueType

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-123 456e-789  -match    -   d     d   e -  d      0x 0-9a-f       or   0xab789  -match    -   d     d   e -  d      0x 0-9a-f       will check for numbers  integers  floats and hex    Please note that this does not cover the case of commas dots being used as separators for thousands

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I ran into this topic while working on input validation with read-host  If I tried to specify the data type for the variable as part of the read-host command and the user entered something other than that data type then read-host would error out  This is how I got around that and ensured that the user enters the data type I wanted   do           try                    int  thing   read-host -prompt  Enter a number or else           GotANumber    true               catch                    GotANumber    false                 until       gotanumber

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Thank you all who contributed to this thread and helped me figure out how to test for numeric values   I wanted to post my results for how to handle negative numbers  for those who may also find this thread when searching     Note  My function requires a string to be passed  due to using Trim     function IsNumeric  value      This function will test if a string value is numeric     Parameters          value   - String to test      return     value Trim    -match    -   0-9

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If you want to check if a string has a numeric value  use this code    a    44 4   b    ad   rtn       double   TryParse  a  ref  rtn   double   TryParse  b  ref  rtn    Credits go here

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itisint  true try    int  vartotest  catch    error converting to int    itisint  false     this is more universal  because this way you can test also strings  read from a file for example  if they represent number  The other solutions using -is  int  result in false if you would have  123  as string in a variable  This also works on machines with older powershell then 5 1

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PS gt  Add-Type -Assembly Microsoft VisualBasic PS gt   Microsoft VisualBasic Information   IsNumeric 1 5  True   http   msdn microsoft com en-us library microsoft visualbasic information isnumeric aspx

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You can check whether the variable is a number like this   val -is  int   This will work for numeric values  but not if the number is wrapped in quotes   1 -is  int  True  1  -is  int  False

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Modify your filter like this   filter isNumeric        Helpers   IsNumeric         function uses the  input variable to contain pipeline information whereas the filter uses the special variable    that contains the current pipeline object   Edit   For a powershell syntax way you can use just a filter  w o add-type    filter isNumeric         return    -is  byte   -or    -is  int16   -or    -is  int32   -or    -is  int64            -or    -is  sbyte  -or    -is  uint16  -or    -is  uint32  -or    -is  uint64           -or    -is  float  -or    -is  double  -or    -is  decimal

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-is and -as operators requires a type you can compare against  If you re not sure what the type might be  try to evaluate the content  partial type list     Invoke-Expression  1 5   GetType   Name -match  byte short int32 long sbyte ushort uint32 ulong float double decimal    Good or bad  it can work against hex values as well  Invoke-Expression  0xA

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filter isNumeric          -is  ValueType      -  1 -is  ValueType  True  1  -is  ValueType  False   -  function isNumeric   Value        return  Value -is  ValueType     isNumeric 1 23 True isNumeric 123 True isNumeric    False isNumeric  asdf123  False   -   Invoke-Expression  1 5   -is  ValueType

[powershell] In PowerShell, how can I test if a variable holds a numeric value?

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