Working with Strings

A string is a piece of text. You write it inside single or double quotes; both work the same way.

greeting = 'Hello'
place = "Kuala Lumpur"

Joining and repeating

The plus sign joins strings (this is called concatenation), and the star repeats one:

full = 'Hello' + ' ' + 'world'   # 'Hello world'
line = 'ab' * 3                  # 'ababab'

Length and indexing

Use len() for the number of characters. Index positions start at 0, and negative indexes count from the end:

word = 'Python'
print(len(word))   # 6
print(word[0])     # P
print(word[-1])    # n

Slicing

A slice takes a range of characters. The start is included and the end is excluded:

word = 'Python'
print(word[0:3])   # Pyt
print(word[2:])    # thon

Useful methods

• upper() and lower() change the case.
• strip() removes spaces from the ends.
• replace(a, b) swaps text a for b.

name = '  ali  '
print(name.strip().upper())   # ALI

f-strings

An f-string lets you drop variables straight into text. Put an f before the quote and wrap the variable in braces:

name = 'Sara'
age = 12
print(f'{name} is {age}')   # Sara is 12

More handy methods

• count(x) counts how many times x appears.
• find(x) gives the index where x first appears, or -1 if not found.
• startswith(x) and endswith(x) return True or False.

text = 'banana'
print(text.count('a'))        # 3
print(text.startswith('ba'))  # True

Splitting and joining

split() breaks a string into a list of pieces, and join() glues a list back into one string:

parts = 'red,green,blue'.split(',')
print(parts)   # ['red', 'green', 'blue']

Checking what is inside

The in keyword tests whether a smaller string appears inside a bigger one:

print('an' in 'banana')   # True
print('z' in 'banana')    # False

This is a quick way to search text without writing a loop.

Escaping quotes

If your text contains a quote, use the other kind of quote around it so Python does not get confused:

sentence = "It's sunny today"
print(sentence)   # It's sunny today

Here double quotes wrap the string so the single quote inside is just an ordinary character.