Number Parsing in Wolfram Language

Parsing numbers from strings is a basic but common task in many programs; here’s how to do it in Wolfram Language.

(* The StringCases function provides the number parsing *)
Needs["StringCases`"]

(* With ToExpression, we can parse floating-point numbers *)
f = ToExpression["1.234"]
Print[f]

(* For parsing integers, we can use ToExpression or IntegerString *)
i = ToExpression["123"]
Print[i]

(* Wolfram Language recognizes hex-formatted numbers *)
d = ToExpression["16^^1c8"]
Print[d]

(* For parsing unsigned integers, we can use FromDigits *)
u = FromDigits["789"]
Print[u]

(* StringCases with NumberString can be used for basic number parsing *)
k = First[StringCases["135", NumberString]]
Print[k]

(* Parsing functions will return $Failed on bad input *)
e = Check[ToExpression["wat"], $Failed]
Print[e]

When you run this script, you should see the following output:

1.234
123
456
789
135
$Failed

In Wolfram Language, we use ToExpression for general parsing of numerical strings. For specific types:

• ToExpression can handle both floating-point and integer parsing.
• Hexadecimal numbers are represented using base notation (e.g., “16^^1c8”).
• FromDigits is useful for parsing unsigned integers.
• StringCases with NumberString can be used for flexible number parsing.

Error handling in Wolfram Language is often done using Check, which allows you to specify a value to return if an error occurs.

Next, we’ll look at another common parsing task: URLs.