int() function in Python

Difficulty Level : Medium
Last Updated : 23 Oct, 2020

int() function in Python and Python3 converts a number in given base to decimal.

Syntax :

int(string, base)

Parameter :

string : consists of 1's and 0's
base : (integer value) base of the number.

Returns :

Returns an integer value, which is equivalent 
of binary string in the given base.

Errors :

TypeError : Returns TypeError when any data type other 
than string or integer is passed in its equivalent position.

Code #1 :

# Python3 program for implementation 
# of int() function 
num = 13
  
String = '187'
  
# Stores the result value of
# binary "187" and num addition 
result_1 = int(String) + num 
print("int('187') + 13 = ", result_1, "\n")
  
# Example_2
str = '100'
  
print("int('100') with base 2 = ", int(str, 2))
print("int('100') with base 4 = ", int(str, 4))
print("int('100') with base 8 = ", int(str, 8))
print("int('100') with base 16 = ", int(str, 16))

Output :

int('187') + 13 =  200 

int('100') with base 2 =  4
int('100') with base 4 =  16
int('100') with base 8 =  64
int('100') with base 16 =  256

Code #2 :

# Python3 program for implementation 
# of int() function 
  
# "111" taken as the binary string 
binaryString = "111"
  
# Stores the equivalent decimal 
# value of binary "111" 
Decimal = int(binaryString, 2) 
  
print("Decimal equivalent of binary 111 is", Decimal) 
  
  
# "101" taken as the octal string
octalString = "101"
  
# Stores the equivalent decimal 
# value of binary "101" 
Octal = int(octalString, 8) 
  
print("Decimal equivalent of octal 101 is", Octal)

Output :

Decimal equivalent of binary 111 is 7
Decimal equivalent of octal 101 is 65

Code #3 : Program to demonstrate the TypeError.

# Python3 program to demonstrate  
# error of int() function 
  
  
# when the binary number is not  
# stored in as string 
binaryString = 111
  
# it returns an error for passing an  
# integer in place of string 
decimal = int(binaryString, 2) 
  
print(decimal)

Output :

Traceback (most recent call last):
  File "/home/d87cec4c0c33aad3bb6187858b40b734.py", line 8, in 
    decimal = int(binaryString, 2)  
TypeError: int() can't convert non-string with explicit base

Application :
It is used in all the standard conversions. For example conversion of binary to decimal, octal to decimal, hexadecimal to decimal.

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