Control Flow

Control Flow is used to determine what code gets executed.

Conditions

Conditions are statements that result in a boolean.

ans = "the sky red?"
# ans = No

Conditional Statements

If-Else Statements

If-else are statement in which if the condition is true, the if block code is executed. For values where condition is false, the else block is executed.

graph LR
  A[Start]
  B{"Am I Tired"}
  C["Sleep"]
  D["Code More"]
  E["Do Something"]

  A --> B
  B -- Yes --> C --> E
  B -- No --> D ---> E

ans = 2
if ans >= 0:
  return "Yes"
else:
  return "No"
# Output: Yes

In this example, 2>0, hence return Yes.

Loops

For Loop

For loop goes through a sequence of element one by one, executing the block of code within itself

graph LR
  A[Start]
  B{"For Condition"}
  C["Execute<br>code below"]
  D["Exit the loop"]
  E["Move on"]

  A --> B
  B -- In range ---> C --> B
  B -- Out of range --> D --> E

friends = ["alice","bella","charlie"]
for i in friends:
  print (i)
''' Output: alice
            bella
            charlie
'''

While Loop

While loop executes the block of code within itself as long as the condition holds true

graph LR
  A[Start]
  B{"While Sunny"}
  C["Go out for a run"]
  D["Exit while loop"]
  E["Move on to other code segments"]

  A --> B
  B -- Sunny ---> C --> B
  B -- Rainy(not sunny) --> D --> E

number = 5
while number > 0: 
  print (number)
  number -= 1  #reduces number by one each time, i.e. 5-1=4, 4-1=3, etc
''' Output: 5
            4
            3
            2
            1
'''

In this case, as long as number>0, the number gets printed. At the point where number =0, while loop terminates. Hence, the final number printed is 1.