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The second pattern disallows leading and trailing spaces and is shorter because in uses the metacharacter \d for digits.If the data is trimmed before validating with an alltrim covered previously, data otherwise valid will pass this test.A valid integer value should contain only digits and possibly a leading minus or plus sign.A regular expression to check that would look like this: These regular expressions are similar to the three above.Returns true if it does, false otherwise % logical procedure is Numeric( string(32) value text ) ; begin logical ok; % the "number" cannot be blank % ok := ( text not = " " ); if ok then begin % there is at least one non-blank character % % must have either an integer or real/immaginary number % % integer: [ |-]digit-sequence % % real: [ |-][digit-sequence].digit-sequence['integer][L] % % or: [ |-]digit-sequence[.[digit-sequence'integer[L] % % imaginary: % % [ |-][digit-sequence].digit-sequence['integer][L]I% % or: [ |-]digit-sequence[.[digit-sequence]]'integer[L]I% % The "I" at the end of an imaginary number can appear % % before or after the "L" (which indicates a long number) % % the "I" and "L" can be in either case % procedure next Char ; char Pos := char Pos 1; logical procedure have( string(1) value ch ) ; ( char Pos 0 and text(max Char//1) = " " do max Char := max Char - 1; % skip leading spacesx % while have( " " ) do next Char; % skip optional sign % if have( " " ) or have( "-" ) then next Char; if have Digit then begin % have a digit sequence % had Digits := true; while have Digit do next Char end if_have_sign ; if have( "." ) then begin % real or imaginary number % next Char; is Real := true; had Digits := had Digits or have Digit; while have Digit do next Char end if_have_point ; % should have had some digits % ok := had Digits; if ok and have( "'" ) then begin % the number has an exponent % is Real := true; next Char; % skip optional sign % if have( " " ) or have( "-" ) then next Char; % must have a digit sequence % ok := have Digit; while have Digit do next Char; end if_ok_and_have_exponent ; % if it is a real number, there could be L/I suffixes % if ok and is Real then begin integer LCount, ICount; LCount := 0; ICount := 0; while have( "L" ) or have( "l" ) or have( "I" ) or have( "i" ) do begin if have( "L" ) or have( "l" ) then LCount := LCount 1 else ICount := ICount 1; next Char end while_have_L_or_I ; % there can be at most one L and at most 1 I % ok := ( LCount = max Char end if_ok ; ok end is Numeric ; % test the is Numeric procedure % procedure test Is Numeric( string(32) value n ; logical value expected Result ) ; begin logical actual Result; actual Result := is Numeric( n ); write( s_w := 0 , """", n, """ is " , if actual Result then "" else "not " , "numeric " , if actual Result = expected Result then "" else " NOT " , "as expected" ) end test Is Numeric ; test Is Numeric( "", false ); test Is Numeric( "b", false ); test Is Numeric( ".", false ); test Is Numeric( ".'3", false ); test Is Numeric( "3.'", false ); test Is Numeric( "0.0z44", false ); test Is Numeric( "-1IL", false ); test Is Numeric( "4.5'23ILL", false ); write( "---------" ); test Is Numeric( "-1", true ); test Is Numeric( " .345", true ); test Is Numeric( "4.5'23I", true ); test Is Numeric( "-5' 3i", true ); test Is Numeric( "-5'-3l", true ); test Is Numeric( " -.345LI", true ); end." " is not numeric as expected "b " is not numeric as expected ". Erlang also has two functions to transform a string to either a floating number or an integer, which will be used in conjunction with The 'from Str' methods return a parsed number or given an error. then then ; s" 1234" is-numeric \ 1234 as integer = 1234s" 1234." is-numeric \ 1234.

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The second pattern disallows leading and trailing spaces and is shorter because in uses the metacharacter \d for digits.

If the data is trimmed before validating with an alltrim covered previously, data otherwise valid will pass this test.

A valid integer value should contain only digits and possibly a leading minus or plus sign.

A regular expression to check that would look like this: These regular expressions are similar to the three above.

Returns true if it does, false otherwise % logical procedure is Numeric( string(32) value text ) ; begin logical ok; % the "number" cannot be blank % ok := ( text not = " " ); if ok then begin % there is at least one non-blank character % % must have either an integer or real/immaginary number % % integer: [ |-]digit-sequence % % real: [ |-][digit-sequence].digit-sequence['integer][L] % % or: [ |-]digit-sequence[.[digit-sequence]]'integer[L] % % imaginary: % % [ |-][digit-sequence].digit-sequence['integer][L]I% % or: [ |-]digit-sequence[.[digit-sequence]]'integer[L]I% % The "I" at the end of an imaginary number can appear % % before or after the "L" (which indicates a long number) % % the "I" and "L" can be in either case % procedure next Char ; char Pos := char Pos 1; logical procedure have( string(1) value ch ) ; ( char Pos 0 and text(max Char//1) = " " do max Char := max Char - 1; % skip leading spacesx % while have( " " ) do next Char; % skip optional sign % if have( " " ) or have( "-" ) then next Char; if have Digit then begin % have a digit sequence % had Digits := true; while have Digit do next Char end if_have_sign ; if have( "." ) then begin % real or imaginary number % next Char; is Real := true; had Digits := had Digits or have Digit; while have Digit do next Char end if_have_point ; % should have had some digits % ok := had Digits; if ok and have( "'" ) then begin % the number has an exponent % is Real := true; next Char; % skip optional sign % if have( " " ) or have( "-" ) then next Char; % must have a digit sequence % ok := have Digit; while have Digit do next Char; end if_ok_and_have_exponent ; % if it is a real number, there could be L/I suffixes % if ok and is Real then begin integer LCount, ICount; LCount := 0; ICount := 0; while have( "L" ) or have( "l" ) or have( "I" ) or have( "i" ) do begin if have( "L" ) or have( "l" ) then LCount := LCount 1 else ICount := ICount 1; next Char end while_have_L_or_I ; % there can be at most one L and at most 1 I % ok := ( LCount = max Char end if_ok ; ok end is Numeric ; % test the is Numeric procedure % procedure test Is Numeric( string(32) value n ; logical value expected Result ) ; begin logical actual Result; actual Result := is Numeric( n ); write( s_w := 0 , """", n, """ is " , if actual Result then "" else "not " , "numeric " , if actual Result = expected Result then "" else " NOT " , "as expected" ) end test Is Numeric ; test Is Numeric( "", false ); test Is Numeric( "b", false ); test Is Numeric( ".", false ); test Is Numeric( ".'3", false ); test Is Numeric( "3.'", false ); test Is Numeric( "0.0z44", false ); test Is Numeric( "-1IL", false ); test Is Numeric( "4.5'23ILL", false ); write( "---------" ); test Is Numeric( "-1", true ); test Is Numeric( " .345", true ); test Is Numeric( "4.5'23I", true ); test Is Numeric( "-5' 3i", true ); test Is Numeric( "-5'-3l", true ); test Is Numeric( " -.345LI", true ); end." " is not numeric as expected "b " is not numeric as expected ". Erlang also has two functions to transform a string to either a floating number or an integer, which will be used in conjunction with The 'from Str' methods return a parsed number or given an error. then then ; s" 1234" is-numeric \ 1234 as integer = 1234s" 1234." is-numeric \ 1234.

" is not numeric as expected ".'3 " is not numeric as expected "3.' " is not numeric as expected "0.0z44 " is not numeric as expected "-1IL " is not numeric as expected "4.5'23ILL " is not numeric as expected --------- "-1 " is numeric as expected " .345 " is numeric as expected "4.5'23I " is numeric as expected "-5' 3i " is numeric as expected "-5'-3l " is numeric as expected " -.345LI " is numeric as expected String numeric String = '123456'; String partly Numeric String = '123DMS'; String decimal String = '123.456'; System.debug(numeric Numeric()); // this will be true System.debug(partly Numeric Numeric()); // this will be false System.debug(decimal Numeric()); // this will be false System.debug(decimal String.remove('.')Numeric()); // this will be true Auto Hotkey has no explicitly defined variable types. cc -c c cc -o isnumber o -lbacon -lm Done, program 'isnumber' ready. The 'false' tells each method to return null if the string does not parse as a number of given type, otherwise, the 'from Str' method throws an exception. as double = 1234s" 1234e" is-numeric \ 1234e as float = 1234.s" $1234" is-numeric \ $1234 as integer = 4660 ( hex literal )s" 10" is-numeric \ 10 as integer = 10 ( binary literal )s" beef" is-numeric \ beef isn't numeric in base 10hexs" beef" is-numeric \ beef as integer = BEEFs" &1234" is-numeric \ &1234 as integer = 4D2 ( decimal literal ) Free BASIC has a built-in Val() function which converts numeric strings to doubles.

A number with leading and trailing spaces can be considered valid because conversion to numeric data will ignore the spaces.

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begin % determnines whether the string contains an integer, real or imaginary % % number. exp); ( out$float2fraction$"1.2"& out$float2fraction$"1.02"& out$float2fraction$"1.01"& out$float2fraction$"10.01"& out$float2fraction$"10.01e10"& out$float2fraction$"10.01e1"& out$float2fraction$"10.01e2"& out$float2fraction$"10.01e-2"& out$float2fraction$"-10.01e-2"& out$float2fraction$"-10e-2"& out$float2fraction$"0.000"); is Numeric("12"): true is Numeric(" 12 "): true is Numeric("hello12"): false is Numeric("-12"): true is Numeric("02"): true is Numeric("0-12"): false is Numeric(" 12"): true is Numeric("1.5"): true is Numeric("1,000"): true is Numeric("1_000"): true is Numeric("0x10"): false is Numeric("0b10101111_11110000_11110000_00110011"): false is Numeric("-0b10101"): false is Numeric("0x10.5"): falseis Numeric("12"): true is Numeric(" 12 "): true is Numeric("hello12"): false is Numeric("-12"): true is Numeric("02"): true is Numeric("0-12"): false is Numeric(" 12"): true is Numeric("1.5"): true is Numeric("1,000"): true is Numeric("1_000"): true is Numeric("0x10"): true is Numeric("0b10101111_11110000_11110000_00110011"): true is Numeric("-0b10101"): false is Numeric("0x10.5"): false, which will return true if the argument passed is either an integer or a float.The following three different formats are demonstrated The first regular expression allows one or more characters in the set [0-9] preceded or followed by any number of spaces within the length of the string.The metacharacters ^ and $ meaning beginning and end of string respectively excludes any characters other than specified in the pattern.The second regular expression is nearly the same as the first with one difference.It not only allows leaving off the cents, but will accept part of a decimal: the decimal point followed by zero, one, or two digits.

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