How to Slice Strings in Python

In Python, when you need to get a sequence of characters from a string (i.e., a substring), you get a slice of the string using the following syntax:

substring = original_string[first_pos:last_pos]

When slicing in Python, note that:

1. The slice begins with the character at first_pos and includes all the characters up to but not including the character at last_pos.
2. If first_pos is left out, then it is assumed to be 0. So "hello"[:3] would return "hel".
3. If last_pos is left out, then it is assumed to be the length of the string, or in other words, one more than the last position of the string. So "hello"[3:] would return "lo".

The following code shows how to get substrings using slicing.

phrase = "Monty Python"

first_5_letters = phrase[0:5]
#[Monty] Python
print(first_5_letters)

letters_2_thru_4 = phrase[1:4]
#M[ont]y Python
print(letters_2_thru_4)

letter_5_to_end = phrase[4:]
#Mont[y Python]
print(letter_5_to_end)

last_3_letters = phrase[-3:]
#Monty Pyt[hon]
print(last_3_letters)

first_3_letters = phrase[:3]
#[Mon]ty Python
print(first_3_letters)

three_letters_before_last = phrase[-4:-1]
#Monty Py[tho]n
print(three_letters_before_last)

copy_of_string = phrase[:]
#[Monty Python]
print(copy_of_string)

The expected output for each print statement is shown in square brackets in the preceding comment.