Ivan R
0
Q:

python what is the syntax for loops

#x starts at 1 and goes up to 80 @ intervals of 2
for x in range(1, 80, 2):
  print(x)
38
# For Loops — In Python, for loops are used for iterating over a 
# sequence (a list, a tuple, a dictionary, a set, or a string)
# Basic syntax:
for variable in sequence_youre_iterating_over:
  something you want to do each iteration
  something else you want to do each iteration

# Note, you don't need to define an indexing variable in Python
# Note, "variable" takes the value of the current item in the 
# 	sequence_youre_iterating_over. If you want it to take on numbers 
# 	(E.g. 0,1,2,3,4...) use: for variable in range(end_number):
# Note, the stuff you do during each iteration is indicated by indenting
# 	it (tab or 4 spaces) - you don't need to surround it in braces { }
# Note, use break to exit the loop entirely if some condition is true and
# 	use continue to skip to the next iteration if some condition is true

# Example usage:
my_list = ["some", "crazy", "text"]
for words in my_list:
  print(words)
--> some
--> crazy
--> text

# Example usage 2:
for i in range(1, 6, 2): # Range takes arguments (start, stop, step)
  print(i)
--> 1
--> 3
--> 5

# Example usage 3:
for i in range(7):
  if i == 2:
    i += 1   # += is shorthand for: i = i + 1
    continue # If i = 2, continue skips to the next iteration of the loop
  if i == 4:
    break # If i = 4, break exits the loop entirely
  print(i)
  i += 1
--> 0
--> 1
--> 3

# While Loops
# Basic syntax:
while condition_to_check:
  something you want to do as long as condition_to_check is true
  something else you want to do as long as condition_to_check is true

# Note, make sure that the condition_to_check will return false at some
# 	point, otherwise you'll be stuck in an infinite loop
# Note, for more complicated conditions_to_check, you may need to use
# 	parentheses to clarify the argument. E.g.:
#	while (i < 10 and (j >= 5 or k == "some_text")):
# Note, indentation, break, and continue work the same as for for loops
  
# Example usage:
i = 0
while i < 3: # True as long as i is less than 3
  print(i)
  i += 1 # += is shorthand for: i = i + 1
--> 0 # Python is 0-indexed, so zero is printed first
--> 1
--> 2

# Example usage 2:
i = 0
while i < 3:
  print(i)
  i += 1
else:
  print("Something to do once, immediately after the loop terminates")
--> 0
--> 1
--> 2
--> Something to do once, immediately after the loop terminates
2

  fruits = ["apple", "banana", "cherry"]
for 
  x in fruits:

	 
	print(x)
 
8
# Quality 101 with for loops. It's basically a for each loop. 
# I know how frustrating they can be at first so just work with them as mutch as possible

# I use different variables to show that you can use different outputs methods

def forloops():
    list_ = ["a", "b", "c", "d", "e"]

    # Normal for loops
    output_list = []
    for i in list_:
        output_list.append(i)
    print(f"Normal list output: {output_list}")

    # Enumerate [extracting tuples]
    output_list = []
    for i in enumerate(list_):
        output_list.append(i)
    print(f"Enumerate output: {output_list}")

    # Enumerate [extracting seperate values]
    output_list = {}
    for x, y in enumerate(list_):
        output_list[x] = y
    print(f"Enumerate output: {output_list}")

    # Range [Can be used in multiple ways]
    # range(<from>, until, <skips>)
    output_list = []
    for i in range(5):
        output_list.append(i)
    print(f"Range output: {output_list}")

    output_list = []
    for i in range(3, 10, 3):
        output_list.append(i)
    print(f"Range output: {output_list}")

forloops()
0

New to Communities?

Join the community