parse method Null safety
- String source,
- {int? radix,
- @deprecated int onError(
- String source
Parse source
as a, possibly signed, integer literal and return its value.
The source
must be a non-empty sequence of base-radix
digits,
optionally prefixed with a minus or plus sign ('-' or '+').
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' with
values 10 through 35. Also accepts upper-case letters with the same
values as the lower-case ones.
If no radix
is given then it defaults to 10. In this case, the source
digits may also start with 0x
, in which case the number is interpreted
as a hexadecimal integer literal,
When int
is implemented by 64-bit signed integers,
hexadecimal integer literals may represent values larger than
263, in which case the value is parsed as if it is an
unsigned number, and the resulting value is the corresponding
signed integer value.
For any int n
and valid radix r
, it is guaranteed that
n == int.parse(n.toRadixString(r), radix: r)
.
If the source
string does not contain a valid integer literal,
optionally prefixed by a sign, a FormatException is thrown
(unless the deprecated onError
parameter is used, see below).
Instead of throwing and immediately catching the FormatException, instead use tryParse to handle a parsing error.
Example:
var value = int.tryParse(text);
if (value == null) {
// handle the problem
// ...
}
The onError
parameter is deprecated and will be removed.
Instead of int.parse(string, onError: (string) => ...)
,
you should use int.tryParse(string) ?? (...)
.
When the source string is not valid and onError
is provided,
whenever a FormatException would be thrown,
onError
is instead called with source
as argument,
and the result of that call is returned by parse.
Implementation
external static int parse(String source,
{int? radix, @deprecated int onError(String source)?});