Python Principles

How to convert an integer to a string

To convert an integer to a string, use the str() built-in function.

The function takes an integer (or other type) as its input and produces a string as its output.

Examples

Here's one example:

>>> str(123)
'123'

If you have a number in a variable, you can convert it like this:

>>> number = 999
>>> number_as_string = str(number)
>>> number_as_string
'999'

Concatenating strings and integers

Sometimes you need to construct a string that contains a number from another variable. Here is an example:

>>> week = 33
>>> greeting = "it is week " + str(week)
>>> greeting
'it is week 33'

Avoiding conversions

Usually, people need the str() function when they want to concatenate a number and a string. This happens right before printing. For example:

>>> name = "Bob"
>>> age = 33
>>> print(name + " is " + str(age) + " years old")
Bob is 33 years old

However it is much cleaner to use the .format() method on strings instead:

>>> print("{name} is {age} years old".format(name=name, age=age))
Bob is 33 years old

It is even cleaner to use f-strings, a new feature in Python 3:

>>> print(f"{name} is {age} years old")
Bob is 33 years old

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