String
Info:
String is a data type in Python that includes plain text. You can include numbers too, but you can NOT use numbers as a string in mathematical operations.
Example 1:
print("Astonish Academy")
This will result in this:
Astonish Academy
Example 2:
What if you want to create a new line inside the string? You can do it by adding \n between the words like in the example below:
print("Astonish\nAcademy")
And the result will be like this:
Astonish
Academy
Single Quotes and Double Quotes:
You can write strings with both single or double cotation marks. Here's an example:
print("Astonish Academy")
and
print('Astonish Academy')
will both result in this outpui:
Astonish Academy
This can be useful if you have to use " inside your string, this way it will NOT end the the string. For example:
print('Astonish "Academy"')
and this will result in
Astonish "Academy"
Or else if you want to use double quotation mark inside a double quoation mark string, you can use \ because it has escape character value. For example:
print("Astonish\"Academy")
will output as
Astonish"Academy
What if you don't want to escape the character with \ but instead you want to include it in your string?
Well you can do it by inserting r before the first quote. Here's an example:
message = r'C:\python\bin'
In the example above, the character \ will be used as it is.
Triple Quotes:
You can also use triple single quotes or triple double quotes in your strings. They are used for multiple line strings.
Here is an example below:
s = ''' string can span
multiple line '''
print(s)
The example above will output as:
string can span
multiple line
String Variables:
You can also create string variables too. For example:
phrase = "Giraffe Academy"
print(phrase)
And this will output as:
Giraffe Academy
Concatenation:
This means taking a string and appending an other string onto it.
phrase = "Giraffe Academy"
print(phrase + " is cool.")
which will result as:
Giraffe Academy is cool.
Note the white space left in the beginning of the " is cool." string to add a space after the word Academy.
F-strings:
F-strings, let's you use the value of a variable, inside an other variable. You do it by placing the letter f before the opening quotation mark and put the brace around the variable name.
For example:
name = 'Garo'
message = f'Hi {name}'
And the output will be:
Hi Garo
This feature was introduced with the Python version 3.6.
Slicing Stings:
Slicing allows you to get a substring from a string. For example:
car = 'Astonish'
print(str[0:5])
will slice the string and give you as an output the range between the index 0 and 5:
Aston
The car[0:5] returns a substring that includes the character from the index 0 (included) to 5 (excluded).
The syntax for slicing is as follows:
string[start:end]
The substring always includes the character at the start and excludes the string at the end.
While slicing, putting the start or the end is optional. If you don't put the start, then it will default to zero. If you don't put the end, then it will default to the string's length.
How to modify the strings with slicing?
It is easier to explain it with an example.
string = 'Lamborghini'
string_new = 'W' + string[1:]
print(string.new)
So basically, strings are immutable. You can NOT modify a string. If you need to do it, you have to create a new string.
If you check the example above, it is NOT modifying the original string. Instead, it is creating a new string called string_new . The new string is created with the concatenation of the letter W and the original string without the first letter by slicing it because we did not specify the end of the slice, so it takes the full length of the string after the first letter.
So the output will be like the following:
Wamborghini
Functions Example 1:
You can use functions to modify your strings or to get information about our strings.
Here's an example:
phrase = "Giraffe Academy"
print(phrase.lower())
and this will output as:
giraffe academy
As you can see. It took the string and converted it all to lowercase letter.
Functions Example 2:
Now let's convert them all to upper case.
phrase = "Giraffe Academy"
print(phrase.upper())
and here's the output:
GIRAFFE ACADEMY
Functions Example 3:
You can also check if a string is entirely upper case. This will give you a True or False result. Here's an example:
phrase = "Giraffe Academy"
print(phrase.isupper())
and the output is:
False
Functions Example 4:
You can also use the functions in combination to each other. For example:
phrase = "Giraffe Academy"
print(phrase.upper().isupper())
So the example above will first run the upper function, converting it all to the upper case and then will check with the isupper function to see if all the letters are upper case. And this is the output:
True
Function Example 5:
We can also figure out the length of our string. For example:
phrase = "Giraffe Academy"
print(len(phrase))
And the example above will count the number of characters that are inside the string and give the result as:
15
Function Example 6:
We can also grab an individual character from the string. For example:
phrase = "Giraffe Academy"
print(phrase[0])
Using the [] (open and close square bracket), we can specify the index of the character that we want to grab. The example above will result in:
G
Function Example 7:
An other interesting function is index. This will tell use where a specific character is located in our string.
phrase = "Giraffe Academy"
print(phrase.index("G")
And the example above will return as the index of the character G and since it is the first letter in our string, the result should be:
0
The function above shows us the first time that the character appears in our string. You can also put words into it if you prefer:
phrase = "Giraffe Academy"
print(phrase.index(Acad))
and this will result in:
8
Function Example 8:
You can also replace characters or words with this function. For example:
phrase = "Giraffe Academy"
print(phrase.replace("Giraffe", "Garo"))
Note that here we have to put 2 arguments. This will result in:
Garo Academy