CS50P W0 - Functions & Variables

Concatenation

print("hello, " + name)

F-string

print(f"hello, {name}")

Adds space automatically sep=" "

print("hello, ", name)

Replace automatic new line end="\n"

print("hello, ", end="")
print(name)

Print "" inside of " "

print('hello, "friend"') or print("hello, \"friend\"")

Remove char from string

name = name.remove("c")
print(f"hello, {name}")

Remove whitespace before and after word

name = name.strip()
print(f"hello, {name}")

Remove prefix

str.removeprefix("$")

Remove suffix

str.removesuffix("%")

Replace one argument by another

s = "hello world"
s = s.replace(" ", "...")

Output:

`hello…world`

Capitalize first letter of first word

name = name.capitalize()
print(f"hello, {name}")

Capitalize first letter of each word

name = name.title()
print(f"hello, {name}")

Combine several methods

name = name.strip().title()
or
name = input("What's your name? ").strip().title()

Split sentences

first, last = name.split(" ")
print(f"hello, {first}")

Python interactive mode >>>

`python` to enter
`ctrl + d` to exit

Convert user input to int or float

x = int(input("What's x? "))
x = float(input("What's x? "))

Round float to the nearest integer

x = float(input("What's x? "))
y= float(input("What's y "))
z = round(x + y)

Specify the number of digits to round to

round(number[n, ndigits])
z = round(x / y, 2)
or
print(f"{z:.2f}")

Format long numbers to include commas or points

print(f"{z:,}")

Define our own function

def function_name():
	...
	...
def hello(to):
    print("hello,", to)

Assign a default value to the parameter to

def hello(to="world")
    print("hello,", to)

hello()
name = input("What’s your name? ")
hello(name)

Define a main() function

def main():
	name = input("What's your name? ")
	hello(name)

def hello(to="world"):
	print("hello,", to)

main()

Very important to call main() at the end of the file and to pass the variable between functions (scope)

Define a function that returns square of n

def square(n):
	return n * n
	or
	return pow(n, 2) 	#(number, exponent)

Define a function to raise to the power of 2

def power(n):
	return n ** 2

Split a camel case string (camelCaseString) into several substrings (regex)

import re

def split_camel_case(s):
    return re.split("(?=[A-Z])", s)

Concatenate all elements of a list into a single string

"<Separator>".join(list)

Iterate through a string to find vowels

def vowelless():
	vowels = ["A", "a", "E", "e", "I", "i", "O", "o", "U", "u"]
	for c in txt:
    	if c in vowels:
	    	…

Irritate through each index [i] and character c in a string

for i, c in enumerate(string):
    …

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