• Ruby

i = s.to_i(2)

• Clojure

(def i (read-string (str "2r" s)))

• C++

int i = std::stoi(s, nullptr, 2);

• C#

int i = int.Parse(s, System.Globalization.NumberStyles.BinaryNumber);

• Dart

var i = int.parse(s, radix: 2);

• Erlang

erlang:list_to_integer(S,2).

• Fortran

character (len=:), allocatable :: s
integer :: i  
s = '1101'
read (s,'(B4)') i

  

• Go

i, err := strconv.ParseInt(s, 2, 0)

• JS

const i = parseInt(s, 2)

• Java

int i = new BigInteger(s, 2).intValue();

• Java

Integer i = Integer.valueOf(s, 2);

• Java

int i = s.chars()
    .map(x -> x - '0')
    .reduce(0, (a, b) -> a * 2 + b);

• PHP

$i = bindec($s);

• Pascal

i := StrToInt('%'+s);

• Perl

$i = oct('0b' . $s);

• Python

i = 0
for x in map(int, s):
    i = i * 2 + x

• Python

i = int(s, 2)

• Rust

let i = i32::from_str_radix(s, 2).expect("Not a binary number!");