This function examines the argument (StringExpression) and returns one of the values:

• -1 StringExpression contains an entirely numeric value.
• 0 StringExpression is not a numeric value.
• >0 The first (leftmost) part of StringExpression is numeric. The value returned indicates how many leading characters are numeric.

Note the following points:

• Any leading spaces are included in the returned value.
• Exponential (scientific) number formats are recognised. eg The string "3E2" is recognised as the numeric value 3*102 and the value -1 is returned.
• The function does not perform any conversions. Conversions take place automatically, when required.

The following example shows how the function may be used to separate a string value into numeric and non-numeric parts.

string s
number n, x

s = "123abc"                       | initial String value
n = s                                     | automatic conversion: n = 123
x = IsNumber(s)                 | x = 3: size of numeric part of s
Left(s, IsNumber(s)) = ""  | s = "abc"
s = "123abc"
s = Left(s, IsNumber(s))    | s = "123"