Function atoi

pub fn atoi<I>(text: &[u8]) -> Option<I>
where
    I: FromRadix10SignedChecked,

Parses an integer from a slice.

Contrary to its ‘C’ counterpart atoi is generic and will require a type argument if the type inference can not determine its result. It will also check for overflow / underflow and allow for Signs.

Use FromRadix10 or FromRadix10Checked directly if you do not want to allow signs. Use FromRadix10 or FromRadix10Signed if you want to opt out overflow / underflow checking.

Example

use atoi::atoi;
// Parsing to digits from a slice
assert_eq!(Some(42), atoi::<u32>(b"42"));
// Additional bytes after the number are ignored. If you want to know how many bytes were used
// to parse the number use `FromRadix10::from_radix_10`.
assert_eq!(Some(42), atoi::<u32>(b"42 is the answer to life, the universe and everything"));
// `None` is returned if the slice does not start with a digit
assert_eq!(None, atoi::<u32>(b"Sadly we do not know the question"));
// While signed integer types are supported...
assert_eq!(Some(42), atoi::<i32>(b"42"));
// Signs are allowed.
assert_eq!(Some(-42), atoi::<i32>(b"-42"));
// Leading zeros are allowed
assert_eq!(Some(42), atoi::<u32>(b"0042"));
// Overflows will return `None`
assert_eq!(None, atoi::<u8>(b"256"));

Return

Returns a a number if the slice started with a number, otherwise None is returned.