Convert integer to string in Python

In Python an integer can be converted into a string using the built-in str() function. The str() function takes in any python data type and converts it into a string. But use of the str() is not the only way to do so. This type of conversion can also be done using the “%s” keyword, the .format function or using f-string function.

Below is the list of possible ways to convert an integer to string in python:

1. Using str() function

Syntax: str(integer_value)

Example:

Python3

num = 10

# check  and print type of num variable
print("Type of variable before conversion : ", type(num))

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

# check  and print type converted_num variable
print("Type After conversion : ",type(converted_num))

Output:

Type of variable before conversion :  <class 'int'>
Type After conversion :  <class 'str'>

2. Using “%s” keyword

Syntax: “%s” % integer

Example:

Python3

num = 10

# check  and print type of num variable
print("Type of variable before conversion : ", type(num))

# convert the num into string and print
converted_num = "% s" % num
print("Type after conversion : ", type(converted_num))

Output:

Type of variable before conversion :  <class 'int'>
Type after conversion :  <class 'str'>

3. Using .format() function

Syntax: ‘{}’.format(integer)

Example:

Python3

num = 10

# check  and print type of num variable
print("Type before conversion : ", type(num))

# convert the num into string and print
converted_num = "{}".format(num)
print("Type after conversion :",type(converted_num))

Output:

Type before conversion :  <class 'int'>
Type after conversion : <class 'str'>

4. Using f-string

Syntax: f'{integer}’

Example:

Python3

num = 10

# check  and print type of num variable
print("Type before conversion : ",type(num))

# convert the num into string
converted_num = f'{num}'

# print type of converted_num
print("Type after conversion : ", type(converted_num))

Output:

Type before conversion :  <class 'int'>
Type after conversion :  <class 'str'>

5. Using __str__() method 

Syntax:  Integer.__str__()

Python3

num = 10

# check  and print type of num variable
print("Type before conversion : ",type(num))

# convert the num into string
converted_num = num.__str__()

# print type of converted_num
print("Type after conversion : ", type(converted_num))

Output:

Type before conversion :  <class 'int'>
Type after conversion :  <class 'str'> 

                                                                                                6. Using str.isdigit() 

Python3

str_value = "1234"
if str_value.isdigit():
    int_value = int(str_value)
    print(int_value)
    print(type(int_value))
else:
    raise ValueError("Invalid literal for int(): {}".format(str_value))

Output

1234
<class 'int'>

7.Using join() method:

 join() method is used to convert a list of integers to a string. We convert the integer to a list of characters using the list() function and then join them using the join() method.

Python3

num = 10

# check  and print type of num variable
print("Type before conversion : ",type(num))

# convert the num into string
converted_num = ''.join(list(str(num)))

# print type of converted_num
print("Type after conversion : ", type(converted_num))

Output

Type before conversion :  <class 'int'>
Type after conversion :  <class 'str'>

Time Complexity: O(N) where n is the number of digits in the integer. 

Space Complexity:O(N) as we need to create a list of characters that has n elements,