# Topic covered
* Flow Control
* Conditional / Decision Making statements
    * if, if-else, if-elif-else
* Iterative Statements
    * for, while
* Transfer Statements
    * break, continue, pass

3 Flow Control

Flow control describes the order in which statements will be executed at runtime.

Python has 3 types of control-flow

• Conditional Statements or Decision Making statements

if
if-else
if-elif-else

• Iterative Statements

for
while

• Transfer Statements

break
continue
pass

3.1 Conditional (Decision-Making) statements

It is kind of making decision during occurred situation of program execution and action can be taken according to specified conditions.

Structure of decision-making evaluate several expressions that provide True or False as a result.

It is up to you to decide which type of action want to take and execute the statements based upon True and False.

# if Statements
age=18
if age>=18:
    print("You are eligible to vote")

if-else statement have a block of code, where if is executed when it is 1 or True and else when if is 0 or False

# if-else satetements
n1, n2 = 2, 4
if n1>n2:
    print("if")
else:
    print("else")

The elif statement is used to check for the multiple True expressions and so on if the condition is True it execute a block of code.

# if-elif-else statement
n = 2
if n==0:
    print("if")
elif n==1:
    print("elif")
else:
    print('else')

Nested if-else statement is used to check condition inside another check condition

# Nested if-else statement
price = 33
if price > 30:
    if price > 100:
        print("if-if")
    else:
       print("if-else") 
elif price > 20:
    if price > 15:
        print("elif-if")
    else:
       print("elif-else") 
else:
    print("else")

3.2 Iterative Statements

In loop, the statements are sequentially executed, execution of first function statement is done first, then second and so on.

In situation where you need to perform a block of code many times then loop statement will come in to picture.

It allows to execute/run group of statements or a statement multiple time.

for loop

If we want to execute some action for every element present in some sequence(it may be string or collection)then we use for loop.

nlist = ['Amrit', 1, 2, 3, 4, 'apple', 'banana']
for x in nlist:
    print(x, end=', ')
# Amrit, 1, 2, 3, 4, apple, banana,

for i in range(1, 5):
    print(i, end=' ')
# 1 2 3 4

for i in range(0, 7, 2):
    print(i, end=' ')
# 0 2 4 6

# Nested Loops
for i in range(4):
    for j in range(4):
        print((i, j), end=', ')
    print()
# (0, 0), (0, 1), (0, 2), (0, 3), 
# (1, 0), (1, 1), (1, 2), (1, 3), 
# (2, 0), (2, 1), (2, 2), (2, 3), 
# (3, 0), (3, 1), (3, 2), (3, 3)

while loop

If we want to execute a group of statements iteratively until some condition false, then we should go for while loop.

total_amount=200
while total_amount > 0:
    print(total_amount)
    total_amount=total_amount-100
else:
    print("Put more money bank people")
    
# 200
# 100
# Put more money bank people

# Infinite Loops
i=0;
while True:
    i=i+1;
    print("Hello", i)

3.3 Transfer Statements

break

It is used for a premature terminates of current loop immediately and executes the further statement, just like break statement in C language.

for i in range(10):
    if i==7:
        print("processing is enough..plz break")
        break

# processing is enough..plz break

continue

We can use continue statement to skip current iteration ithout performing remaining statements in present iteration and continue next iteration.

for i in range(10):
    if i%2==0:
        continue
    print(i, end=' ')
# 1 3 5 7 9

pass

Used to define an empty block with pass keyword.

The pass statement is considered as a null statement which won't do anything. It is useful when a code (i.e., code required in future) has not written till now, but your code will go eventually.

def m1():
    pass


for i in range(20):
    if i%9==0:
        print(i, end=' ')
    else:
        pass
# 0 9 18