Loops

Loops allows the lines of code to run over and over again

for Loops

Iterable - list, dictionary, tuple, set, string An iterable is any Python object capable of returning its elements one at a time.
Iterate -> one by one check each item in the collection

for loops allow us to iterate over anything that has a collection of items

for item in 'Zero':
    print (item)                    #creates a variable, givies iterable item Z      e        r       o

Nested Loops

for item in (1,2,3,4,5):
    for x in ('a', 'b', 'c'):       #nesting in loop
        print(item, x)

Loops using Dict

.items() → key-value pairs
.keys() → keys only
.values() → values only

user = {
    'name': 'marwa',
    'age': 22,
    'can_swim': True
}
for i in user.items():              #.items(), .keys(), .values()
    print(i)

for key, value in user.items():     # Tuple unpacking
    print(key, value)

Range in Loops

range(start, stop, step) generates numbers.

for i in range (10,):            #Output: print numbers 1 to 9, it also has stepover option
    print(i)                     #range(start, stop, stepover)2, 4, 6, 8

A negative step makes the loop count backwards.

for i in range(10, 0, -1):
    print(i)                     # Output: 10, 9, 8, ..., 1

Using strings & list

for _ in range (10):
    print('email list')          #prints email list 10 times

for _ in range (2):              #creates loop of 2 list until 10
    print(list(range(10)))

Enumerate in Loops

enumerate() adds an index while looping.
It is used to loop over an iterable (like a list, tuple, or string) while keeping track of the index of each item.

for i, char in enumerate('hellloooo'):
    print(i, char)                      #we are unpacking, and access the index number of each item

for i, char in enumerate([1,2,3,4,5,6]):
    print(i, char)

while Loop

Executes while condition is True.

While is a loop statement that repeatedly executes a block of code as long as a given condition is True.

count = 1

while count <= 5:           # Loop runs while condition is True
    print(count)
    count += 1              # Increment to avoid infinite loop or you can use break
else:
    print('done')           #else will only execute if there isn't a break

myList1 = [1,2,3]

for i in myList1:
    print(i)                #with for loop

i=0
while i < len(myList1):
    print(myList1[i])
    i+= 1                   #with while loop

break, continue, pass

break → exits loop.
continue → skips current iteration.
pass → placeholder, does nothing.

break in loop

while True:
response = input('say something: ')
if (response == 'bye'):
break

continue in loop

Skips rest of the code in the current iteration and moves to the next iteration of the loop.
With a continue, what we're saying is, hey, whatever happens when you hit this line, continue onto the top of the enclosing loop.

for i in range(5):
    if i == 2:
        continue  # Skip when i is 2
    print(i)

pass in loop

One of those placeholders that we can use so that there is a line of code that does absolutely nothing but we can still pass through.