The String (str) Data Type#
Computers manipulate data. Data can come in several forms. Not all data is handled the same way, so information is organized into different data types or sets of similar values. The same operations can be used to manipulate the data within data types. Consider the following examples:
100 is a numeric data type that can be used in mathematical computations. The '100' in the sentence, 'I have 100 things in my mind.' Is part of a sequence of characters. A series of characters in computer science is called a string.
In Python, strings are sequences of characters enclosed within either single (' ') or double (" ") quotation marks. They are one of the most commonly used data types in Python and are used to represent text-based data.
Strings in Python are immutable, meaning their contents cannot be modified once created. However, you can make new strings by combining or manipulating existing ones. This immutability ensures the integrity of strings, preventing unintended changes to their values after creation.
Strings support various operations and methods for manipulation, including concatenation (joining two or more strings together), slicing (extracting portions of a string), indexing (accessing individual characters by their position), and formatting (inserting values into a string). Additionally, Python provides a rich set of string manipulation functions and methods for tasks such as searching, replacing, and formatting strings.
Python’s string handling capabilities and immutability make them versatile and efficient for tasks ranging from simple text processing to complex data manipulation and formatting.
Strings and Numeric Data Types#
The three examples below demonstrate how a numeric data type differs from a string.
Note
The examples below use the print() function. This will be covered in TODO:SECTION LINK
Example 1:
In Example 1, the numeric data type and the string data type can use the + operator, but the output is very different. In 1 + 2, the + works as expected with numbers and functions as an addition operator, returning a sum of 3 . In '1' + '2', the result is 12. This is because with strings the + is what is known as a concatenation operator, meaning it links sequences of strings together. In '1 + 2', the + is a character in the string.
Example 2:
In Example 3, when attempting to use a + between a string and an integer, the TypeError displayed below is returned.
TypeError: can only concatenate str (not "int") to str
Python operates from left to right and encounters the string first, expecting another string to follow after the +. It cannot use the + operator as an addition operator or a concatenation operator because the two data types are not of the same data type.
Example 3:
Similarly, when Python encounters the numeric data type first, it returns a different type error, expecting another numeric type after the +. This error can be seen below:
TypeError: unsupported operand type(s) for +: 'int' and 'str'
Operating from left to right, Python encounters a numeric data type first, and expects another numeric data type after +. It cannot use the + operator as an addition operator or a concatenation operator because the two data types are not of the same data type.
Creating Strings#
As mentioned above, strings can be created using single quotation marks ' ' or double quotation marks " ". There is no difference between strings created with the two options mentioned. Some programmers prefer single as it is one less keystroke. Others may prefer double, which is more consistent with other programming languages. However, there may be instances where one may have to choose explicitly one or the other to avoid errors.
Consider the following examples:
'They're on their way there.'
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"Eve said that Alice said, "No.""
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'Bob said that Oscar said, "They're on their way there."'
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"Bob said that Oscar said, "They're on their way there.""
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'Bob said that Oscar said, "They\'re on their way there."'
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"Bob said that Oscar said, \"They're on their way there.\""
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