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Knowing how to use and manipulate strings is an essential skill for any programmer, regardless of the coding language you use. This includes the ability to convert data of other types, like integers or float type numbers, into strings. Sometimes, while solving problems, you might have to output/store a string that must contain, as part of the string, a piece of current, updated information stored in some integer variable.
For example, the string may store the number of new sign-ups to a website that day, the number of units of electricity used till now for this month, etc. In such cases, the conversion skills we learn in this article will come in handy.
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In this article, we’ll cover:
There are many in-built tools in Python that facilitate the conversion of an Integer to a String. Note that Python does not support type coercion or any implicit conversion, so we must do it explicitly. Let us look at some of the ways we can convert an Integer to a String in Python. We will use the type() function to check the type of data we’re dealing with before and after attempting conversion.
The str() function is an in-built function in Python that converts an object into a String by internally calling the __str__() method. You can also use __str__() instead of str() directly, but using special methods, which have the format __x__() directly, is generally discouraged. The str() function takes three parameters:
Here’s the syntax to help you understand the format better:
str(object, encoding=encoding, errors=errors)
Let us look at an example to see how it works:
int_to_convert = 10
# printing the type of int_to_convert variable
print(type(int_to_convert))
print(int_to_convert)
# converting the number int_to_convert to string
int_converted_via_str = str(int_to_convert)
# checking the type of int_converted_via_str
print(type(int_converted_via_str))
print(int_converted_via_str)
Output:
<class 'int'>
10
<class 'str'>
10
We can also achieve this conversion from integer to string using the "%s" keyword. This method first converts the object type to a string and then replaces the occurrence of "%s" in the string. It is also used to add a string within another string.
Example:
int_to_convert = 10
# In this example, int_to_convert will be converted into a string
# and will replace the occurrence of "%s" in the passed string.
# checking the type of int_to_convert
print(type(int_to_convert))
print(int_to_convert)
# converting the number int_to_convert to a string
int_converted_via_s = "%s" % int_to_convert
print(type(int_converted_via_s))
print(int_converted_via_s)
<class 'int'>
10
<class 'str'>
10
Yet another way to convert an integer into a string in Python would be using the format function. The format function takes two parameters: The value to format and the format specification on how the value needs to be formatted.
This format specification involves using a placeholder position {} into which the desired value(s) must go. For more information on the format function, check out our page on Python Format Function.
Here’s an example of converting integer to string in Python using format() function:
int_to_convert = 10
# checking type of int_to_convert
print(type(int_to_convert))
print(int_to_convert)
# converting int_to_convert to string using format
int_converted_via_format = "{}".format(int_to_convert)
print(type(int_converted_via_format))
print(int_converted_via_format)
<class 'int'>
10
<class 'str'>
10
The last method on our list that you can use to convert integer to string in Python 3 uses f-string. In Python’s source code, f-string is a literal string, with a prefix f, which stores expressions inside {} braces and provides a way to embed these expressions inside strings, using minimal syntax. Note that you can only use f-string Python 3 onward. It’s not available in Python 2. Let us see how:
int_to_convert = 10
# checking the type of int_to_convert
print(type(int_to_convert))
print(int_to_convert)
# converting int_to_convert to string
int_converted_via_fstring = f'{int_to_convert}'
# printing the type of int_converted_via_fstring
print(type(int_converted_via_fstring))
print(int_converted_via_fstring)
<class 'int'>
10
<class 'str'>
10
Let us look at an example where we concatenate a String and an Integer by converting the integer into a string using the str() function. We can use this when we want to, say, print a string that also contains information stored in an integer variable.
int_to_concatenate = 7
int_to_concatenate_converted = str(7)
# Concatenating the string with the string version of int_to_concatenate
print("A week has " + int_to_concatenate_converted + " days.")
# Returning empty string if no argument is provided
print(str())
Output:
A week has 7 days.
Some better, more succinct ways to concatenate strings than just using str() would include using the format function or, even better: f-strings, which is a new addition in Python 3.
Here’s how we can achieve the same goal using these two tools:
int_to_concatenate = 7
# Concatenates using the format function, without conversion
print("A week has {x} days.".format(x=int_to_concatenate))
Output:
A week has 7 days.
int_to_concatenate = 7
# Concatenates using f-string function, without conversion
print(f"A week has {int_to_concatenate} days.")
Output:
A week has 7 days.
Here are a few examples of technical interview questions that will require you to convert an integer into a string:
Question 1: How can I concatenate multiple integers into part of the same string using the format function?
You can use all of the four methods that we have provided above for this purpose; here’s an example using the format function with multiple placeholders:
Syntax: {}{}{}.format(value_a, value_b, value_c)
Example:
str_one = "String with {} multiple {} placeholders {}! "
str_formatted = str_one.format(5, 6, 7)
print(str_formatted)
Output:
String with 5 multiple 6 placeholders 7!
Question 2: When would we need to convert int to string?
Converting an integer to a string can be useful in the following cases:
Question 3: What are some cases where we need to do the opposite: convert a string to an integer? How can we convert a string into an integer in Python?
One common case of need to convert a string to an integer is that if the input is an integer read as a string, we need to convert the string to an integer to do numerical operations using the input. This conversion can be achieved using the int() function using the syntax: print(int(“String”))
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