## Introduction

Each time through the loop, multiply the current value by 2 and add the next digit's integer value:

## Demo

B = '1101' # Convert binary digits to integer with ord
I = 0 # from ww w .j a va 2 s . co m
while B != '':
I = I * 2 + (ord(B[0]) - ord('0'))
B = B[1:]
print( I )

## Result

A left-shift operation (I << 1) would have the same effect as multiplying by 2 here.

You can use the following function to convert int to binary back and forth.

## Demo

print( int('1101', 2) ) # Convert binary to integer: built-in
print( bin(13) ) # Convert integer to binary: built-in

## Result

## Related Topic