parse method

Parse source as an integer literal and return its value.

int parse(
String source,
{int radix,
int onError(String source)}
)

Parse source as an integer literal and return its value.

The radix must be in the range 2..36. The digits used are first the decimal digits 0..9, and then the letters 'a'..'z'. Accepts capital letters as well.

If no radix is given then it defaults to 10, unless the string starts with "0x", "-0x" or "+0x", in which case the radix is set to 16 and the "0x" is ignored.

The source must be a non-empty sequence of base-radix digits, optionally prefixed with a minus or plus sign ('-' or '+').

It must always be the case for an int n and radix r that n == int.parse(n.toRadixString(r), radix: r).

If the source is not a valid integer literal, optionally prefixed by a sign, the onError is called with the source as argument, and its return value is used instead. If no onError is provided, a FormatException is thrown.

The onError handler can be chosen to return null. This is preferable to to throwing and then immediately catching the FormatException. Example:

var value = int.parse(text, onError: (source) => null);
if (value == null) ... handle the problem

The onError function is only invoked if source is a String. It is not invoked if the source is, for example, null.