Strings

1. Text needs quotes

Quotes tell Python “this is text, not code”. Single or double both work; just close what you open.

food = "pizza"
feeling = 'happy'

print(food)
print("food")   # quotes: prints the word food, not the box

That last line is the classic slip: food opens the variable box, "food" is just the four letters f-o-o-d.

2. Joining strings with +

On strings, + means stick together (the fancy word is concatenation). Python glues exactly what you give it, so spaces are your job:

first = "Hallam"
second = "Coder"

print(first + second)         # HallamCoder, squashed!
print(first + " " + second)   # with a space glued between

3. Stretch, shout, whisper

Three tools you will use constantly:

word = "echo"

print(word * 3)        # * repeats a string
print(word.upper())     # SHOUT IT
print("HELLO".lower())  # whisper it

.upper() and .lower() are written with a dot after the string, and give back a changed copy: the original stays as it was.

4. Measuring with len()

len() counts the characters, spaces included:

print(len("cat"))        # 3
print(len("hello there"))  # 11: the space counts too

name = "Alexandra"
print("Your name has", len(name), "letters")

5. The "55" trap

Here is the sneakiest beginner trap in Python. input() always gives back a string, even when the user types a number. And + on strings joins:

number = input("Type a number: ")
print(number + number)   # surprise!

Type 5 and you get 55, because Python joined the string "5" to the string "5". To do real maths, convert the string into a number with int():

number = int(input("Type a number: "))
print(number + number)   # now it is 10

6. Quick check Part 1 of 2

Six quick questions. This is half of completing the module. The coding task below is the other half.