Python Strings

Strings can be expressed using single quotes (') or double quotes (")

first_name = 'John'
last_name = "Doe"
about = 'John is 21 years old'

Strings are like Lists

Characters in a string can be accessed using the standard [ ] syntax

print(first_name[0])
print(last_name[0])
print(len(first_name))

J
D
4

String Methods

Here are some other commonly used String methods.

1) s.lower(), s.upper() -- returns the lowercase or uppercase version of the string

2) s.strip() -- returns a string with whitespace removed from the start and end

3) s.isalpha()/s.isdigit()/s.isspace() -- tests if all the string chars are in the various character classes

4) s.startswith('other'), s.endswith('other') -- tests if the string starts or ends with the given other string

5) s.find('other') -- searches for the given other string within s, and returns the first index where it begins or -1 if not found

6) s.replace('old', 'new') -- returns a string where all occurrences of 'old' have been replaced by 'new'

7) s.split('delim') -- returns a list of substrings separated by the given delimiter. As a convenient special case s.split() (with no arguments) splits on all whitespace chars.

9) s.join(list) -- opposite of split(). Joins the elements in the given list together using the string as the delimiter.

first_name.lower()      

'john'

last_name.upper()

'DOE'

print(first_name.startswith('A'))
print(first_name.startswith('j'))
print(first_name.startswith('J'))
print(first_name.startswith('Jo'))

False
False
True
True

print(about.find('o'))
print(about.find('u'))

1
-1

split_values = about.split()
split_values 

['John', 'is', '21', 'years', 'old']

rejoin = ' '.join(split_values) 
rejoin

'John is 21 years old'