Strings and Loops

Now that we know that strings are basically lists in disguise, we can start to harness the power of loops with them.

Using a for loop

This for loop creates a variable called letter. It is used to store each character in the string as the loop goes through it, starting at the first character.
The print statement uses the letter variable and will output the string one character at a time (like a list).

Eg:

myString = "Day 38"
for letter in myString:
print(letter)
# This code outputs:
#D
#a
#y
#3
#8
# this is a comment in the code, the computer will ignore it

if statement inside the loop

This code will examine the lower case version of each character. If it's an 'a', the computer will change the font color to yellow before printing.
Outside of the loop, the last line sets the font color back to default for the next character in the loop

Eg:

myString = "Day 38"
for letter in myString:
if letter.lower() == "a":
print('\033[33m', end='') #yellow
print(letter)
print('\033[0m', end='') #back to default
# This code outputs (with a yellow 'a'):
#D
#a
#y
#3
#8

Using a list to specify search items

If the letters are in my list called vowels, they will print out in yellow.
I changed the print statement on the last line back to the default color with the ending system.

Eg:

vowels = ["a","e","i","o","u"]
myString = "Will my vowels now be yellow?"
for letter in myString:

if letter.lower() in vowels:
print('\033[33m', end='') #yellow

print(letter, end="")
print('\033[0m', end='') #back to default

Comments

FOR LOOP , RANGE

FOR LOOP A while loop is perfect to use when we don't know how many times we want the loop to repeat. If we have an idea of how many times we want the loop to repeat, we can use a for loop to loop code in exactly the same way the while loop did. EXAMPLE : for counter in range(10): print(counter) RANGE The range function creates a list of numbers in the range you create. If you only give it one number, it will start at 0 and move to a state where the final number is one less than the number in the brackets. In this case, the final number would be 9 . EXAMPLE : total = 0 for number in range(100) : total += number print(total)

ALL ABOUT WHILE LOOP

WHILE LOOP A while loop allows your code to repeat itself based on a condition you set. EXAMPLE : counter = 0 while counter < 10: print(counter) counter +=1 Infinite Loop You have to be really careful that you don't accidentally invoke an infinite loop! This is where the computer will loop code until the end of time. Without a break. Forever. This is just saying "count to 10 by 1 each time." to make the loop end. Don't forget, if your condition is a > then you might need to -= . This will subtract from the variable instead of adding to it. EXAMPLE : counter = 0 while counter < 10: print(counter) counter += 1

IF AND ELSE STATEMENT

If Statements These statements are a bit like asking a question. You are telling the computer: if something is true, then do this specific block of code. Double equals ( == ) is asking the computer to compare if these two things are exactly the same. EXAMPLE : myName = input("What's your name?: ") if myName == "David": What is else? IF the condition is not met with the if statement, then we want the computer to do the else part instead. Likewise, if the condition is met in the if statement, then the else bit is ignored by the computer. The else statement must be the first thing unindented after the if statement and in line with it EXAMPLE : myName = input("What's your name?: ") if myName == "David": print("Welcome Dude!") print("You're just the baldest dude I've ever seen...

PYTHON SYNTAX

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