Flow of control determines the order in which statements are executed in a Python program. It is controlled using conditional statements, loops, and function calls.
1. Conditional Statements
Conditional statements allow a program to make decisions based on conditions.
1.1 if Statement
Executes a block of code if the condition is True.
x = 10
if x > 5:
print("x is greater than 5")
1.2 if-else Statement
Executes one block of code if the condition is True, otherwise executes another block.
x = 10
if x % 2 == 0:
print("Even number")
else:
print("Odd number")
1.3 if-elif-else Statement
Used when multiple conditions need to be checked.
score = 85
if score >= 90:
print("Grade: A")
elif score >= 80:
print("Grade: B")
elif score >= 70:
print("Grade: C")
else:
print("Grade: F")
2. Looping Statements
Loops are used to execute a block of code multiple times.
2.1 for Loop
Iterates over a sequence (list, tuple, string, etc.).
for i in range(5):
print(i) # Output: 0 1 2 3 4
Iterating over a list:
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
print(fruit)
2.2 while Loop
Repeats a block of code while a condition remains True.
x = 5
while x > 0:
print(x)
x -= 1 # Decrement x
2.3 break and continue
break: Exits the loop early.continue: Skips the current iteration and moves to the next one.
Example using break:
for num in range(10):
if num == 5:
break # Stop loop when num is 5
print(num)
Example using continue:
for num in range(5):
if num == 2:
continue # Skip when num is 2
print(num)
3. Nested Control Structures
Control statements can be nested inside each other.
Example: Nested if Statements
x = 10
y = 5
if x > 5:
if y > 2:
print("Both conditions are True")
Example: Nested Loops
for i in range(3):
for j in range(2):
print(f"i={i}, j={j}")
4. pass Statement
The pass statement is a placeholder used when a statement is syntactically required but no action is needed.
for i in range(5):
if i == 3:
pass # Placeholder for future implementation
print(i)
5. Summary
✅ Conditional statements (if, if-else, if-elif-else) control decision-making.
✅ Loops (for, while) allow repeated execution of code blocks.
✅ break and continue modify loop execution.
✅ Nested control structures enable complex decision-making.
✅ pass is used as a placeholder.
