Convert string to integer in Python

In Python an strings can be converted into an integer using the built-in int() function. The int() function takes in any python data type and converts it into an integer.But use of the int() function is not the only way to do so. This type of conversion can also be done using the float() keyword, as a float value can be used to compute with integers. Below is the list of possible ways to convert an integer to string in python:

1. Using int() function

Syntax: int(string)

Example:

Python3

num = '10'

# check and print type num variable
print(type(num))

# convert the num from string into int
converted_num = int(num)

# print type of converted_num
print(type(converted_num))

# We can check by doing some mathematical operations
print(converted_num + 20)

Output

<class 'str'>
<class 'int'>
30

As a side note, to convert to float, we can use float() in Python

Python3

num = '10.5'

# check and print type num variable
print(type(num))

# convert the num into string
converted_num = float(num)

# print type of converted_num
print(type(converted_num))

# We can check by doing some mathematical operations
print(converted_num + 20.5)

Output

<class 'str'>
<class 'float'>
31.0

2. Using float() function

We first convert to float, then convert float to integer. Obviously the above method is better (directly convert to integer)

Syntax: float(string)

Example:

Python3

a = '2'
b = '3'

# print the data type of a and b
print(type(a))
print(type(b))

# convert a using float
a = float(a)

# convert b using int
b = int(b)

# sum both integers
sum = a + b

# as strings and integers can't be added
# try testing the sum
print(sum)

Output

<class 'str'>
<class 'str'>
5.0

3. converting python string to int using eval() function

Python3

# converting python string to
# int using eval() function
a = "100"
print(eval(a)+12)

Output

112

4. converting python string to float using eval() function

Python3

# converting python string to
# float using eval() function
a = "100.00"
print(eval(a)+12)

Output

112.0

5. Using ast.literal_eval

Python3

from ast import literal_eval

int_value = literal_eval("1234")
print(int_value)
print(type(int_value))

Output

1234
<class 'int'>

6. Using str.isdigit() 

Python3

string = "42"
if string.isdigit():
    integer = int(string)
    print(integer) # Output: 42
else:
    print(f"{string} is not a valid integer.")

Output

42

Note: float values are decimal values that can be used with integers for computation.