Control structures allow you to manage the flow of your Python program. They help you make decisions, repeat tasks, and control loop execution. This lesson will cover:<\/p>\n\n\n\n
Operators: Perform operations on values.<\/p><\/li>\n\n\n\n
If, Else, and Elif Statements: Conditional statements for decision-making.<\/p><\/li>\n\n\n\n
For-loop and While-loop Statements: Repeating code execution.<\/p><\/li>\n\n\n\n
Python supports various operators that allow you to manipulate data and evaluate conditions.<\/p>\n\n\n\n
These perform basic mathematical operations.<\/b><\/p>\n\n\n\n + : Addition<\/p><\/li>\n\n\n\n – : Subtraction<\/p><\/li>\n\n\n\n * : Multiplication<\/p><\/li>\n\n\n\n \/ : Division<\/p><\/li>\n\n\n\n ** : Exponentiation<\/p><\/li>\n\n\n\n % : Modulus (remainder after division)<\/p><\/li>\n\n\n\n \/\/ : Floor division (integer division, without remainder)<\/p><\/li>\n<\/ul>\n\n\n\n Example:<\/b><\/p>\n\n\n\n These are used to compare two values and return True or False.<\/b><\/p>\n\n\n\n == : Equal to<\/p><\/li>\n\n\n\n != : Not equal to<\/p><\/li>\n\n\n\n > : Greater than<\/p><\/li>\n\n\n\n < : Less than<\/p><\/li>\n\n\n\n >= : Greater than or equal to<\/p><\/li>\n\n\n\n <= : Less than or equal to<\/p><\/li>\n<\/ul>\n\n\n\n Example:<\/p>\n\n\n\n These are used to combine conditional statements.<\/p>\n\n\n\n and<\/strong> : Returns True if both statements are true.<\/p><\/li>\n\n\n\n or<\/strong> : Returns True if one of the statements is true.<\/p><\/li>\n\n\n\n not<\/strong> : Reverses the result.<\/p><\/li>\n<\/ul>\n\n\n\n Example:<\/p>\n\n\n\n These conditional statements are used to control the flow of execution based on conditions. Python evaluates conditions and executes the corresponding block of code.<\/p>\n\n\n\n Syntax:<\/p>\n\n\n\n Example:<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The if block executes if the first condition (age < 18) is true. <\/p>\n\n\n\n The elif block executes if the if condition is false but the second condition (age == 18) is true.<\/p>\n\n\n\n The else block executes if none of the conditions are true.<\/p>\n\n\n\n Loops allow you to repeat blocks of code multiple times.<\/p>\n\n\n\n A for loop is used to iterate over a sequence such as a list, tuple, dictionary, string, or range of numbers. The loop runs once for each item in the sequence. Explanation:<\/p>\n\n\n\n The loop iterates over each item in the islands list and prints it.<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop iterates over each character in the string word and prints it.<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop iterates through each key-value pair in the person dictionary and prints them.<\/p>\n\n\n\n The Basic Range Example:<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop runs for each number in the range from 0 to 4.<\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop starts at 2, increments by 2 each time, and stops before reaching 10.<\/p>\n\n\n\n A while loop executes as long as a given condition is true. If the condition never becomes false, the loop will continue indefinitely (becoming an “infinite loop”).<\/p>\n\n\n\n Syntax:<\/p>\n\n\n\n Example:<\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop will keep executing as long as count <= 5 is true. The count variable increments on each iteration.<\/p>\n\n\n\n The break statement immediately terminates the loop, regardless of the loop condition.<\/p>\n\n\n\n Syntax:<\/b><\/p>\n\n\n\n Example:<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The loop stops when number equals 5, even though the loop was designed to run until 9.<\/p>\n\n\n\n The continue statement skips the current iteration and moves to the next iteration of the loop.<\/p>\n\n\n\n Syntax:<\/b><\/p>\n\n\n\n Example:<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n The number 2 is skipped, and the loop continues with the next iteration.<\/p>\n\n\n\n The pass statement is a null operation. It does nothing and is used as a placeholder when a statement is syntactically required but you don’t want to execute any code.<\/p>\n\n\n\n Syntax:<\/b><\/p>\n\n\n\n Example:<\/b><\/p>\n\n\n\n Explanation:<\/p>\n\n\n\n When number equals 1, the pass statement is executed, which does nothing, and the loop continues.<\/p>\n\n\n\n\n
x = 10\ny = 3\n\nprint(x + y)\u00a0 # 13\nprint(x - y) \u00a0 # 7\nprint(x * y) \u00a0 # 30\nprint(x \/ y) \u00a0 # 3.333...\nprint(x % y) # 1\nprint(x \/\/ y)\u00a0 # 3<\/pre><\/div>\n\n\n\n
\n\n\n\nComparison Operators:<\/h3>\n\n\n\n
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x = 5\ny = 10\n\nprint(x == y) \u00a0 # False\nprint(x != y) \u00a0 # True\nprint(x < y)\u00a0 \u00a0 # True\nprint(x > y)\u00a0 \u00a0 # False<\/pre><\/div>\n\n\n\n
\n\n\n\nLogical Operators:<\/h3>\n\n\n\n
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x = 5\ny = 10\n\nprint(x > 3 and y < 15)\u00a0 # True\nprint(x < 3 or y > 15) \u00a0 # False\nprint(not(x == y)) \u00a0 \u00a0 \u00a0 # True<\/pre><\/div>\n\n\n\n
If, Else, and Elif Statements<\/span><\/h2>\n\n\n\n
if condition1:\n \u00a0\u00a0\u00a0# Code to execute if condition1 is True\nelif condition2:\n # Code to execute if condition1 was False and condition2 is True\nelse:\n\u00a0\u00a0\u00a0\u00a0# Code to execute if all conditions are False<\/pre><\/div>\n\n\n\n
age = 20\n\nif age < 18:\n \u00a0\u00a0\u00a0print("You are a minor.")\nelif age == 18:\n \u00a0\u00a0\u00a0print("You are exactly 18 years old.")\nelse:\n\u00a0\u00a0\u00a0\u00a0print("You are an adult.")<\/pre><\/div>\n\n\n\nFor-loop and While-loop Statements<\/h2>\n\n\n\n
For-loop<\/h3>\n\n\n\n
<\/b><\/p>\n\n\n\nLooping through a List:<\/h4>\n\n\n\n
islands = ["Luzon", "Visayas", "Mindanao"]\n\nfor island in islands:\n\u00a0\u00a0\u00a0\u00a0print(island)<\/pre><\/div>\n\n\n\n
\n\n\n\nLooping through a String:<\/h4>\n\n\n\n
word = "Philippines"\n\nfor letter in word:\n \u00a0\u00a0\u00a0print(letter)<\/pre><\/div>\n\n\n\n
\n\n\n\nLooping through a Dictionary:<\/h4>\n\n\n\n
person = {"name": "Maria", "age": 25, "city": "Cebu"}\n\nfor key, value in person.items():\n\u00a0\u00a0\u00a0\u00a0print(f"{key}: {value}")<\/pre><\/div>\n\n\n\n
\n\n\n\nUsing
range()<\/code> in For-loops<\/h4>\n\n\n\nrange()<\/code> function generates a sequence of numbers, often used in for-loops. It can take up to three arguments: start, stop, and step.<\/b><\/p>\n\n\n\nfor i in range(5):\u00a0 # Iterates from 0 to 4\n\u00a0\u00a0\u00a0\u00a0print(i)<\/pre><\/div>\n\n\n\n
\n\n\n\nSpecifying Start, Stop, and Step:<\/h4>\n\n\n\n
for i in range(2, 10, 2):\u00a0 # Iterates from 2 to 8, stepping by 2\n \u00a0\u00a0\u00a0print(i)<\/pre><\/div>\n\n\n\n
\n\n\n\nWhile-loop<\/h3>\n\n\n\n
while condition:\n\u00a0\u00a0\u00a0\u00a0# Code to execute while the condition is True<\/pre><\/div>\n\n\n\n
count = 1\n\nwhile count <= 5:\n \u00a0\u00a0\u00a0print("Count:", count)\n \u00a0\u00a0\u00a0count += 1<\/pre><\/div>\n\n\n\nControl Flow Statements: break, continue, and pass<\/h2>\n\n\n\n
break Statement<\/h3>\n\n\n\n
for variable in sequence:\n \u00a0\u00a0\u00a0if condition:\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0break\n\u00a0\u00a0\u00a0\u00a0# Other code to execute<\/pre><\/div>\n\n\n\n
for number in range(10):\n \u00a0\u00a0\u00a0if number == 5:\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0break\n\u00a0\u00a0\u00a0\u00a0print(number)<\/pre><\/div>\n\n\n\n
\n\n\n\ncontinue Statement<\/h3>\n\n\n\n
for variable in sequence:\n \u00a0\u00a0\u00a0if condition:\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0continue\n\u00a0\u00a0\u00a0\u00a0# Code to execute if condition is not met<\/pre><\/div>\n\n\n\n
for number in range(5):\n \u00a0\u00a0\u00a0if number == 2:\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0continue\n\u00a0\u00a0\u00a0\u00a0print(number)<\/pre><\/div>\n\n\n\n
\n\n\n\npass Statement<\/h3>\n\n\n\n
if condition:\n \u00a0\u00a0\u00a0pass\nelse:\n\u00a0\u00a0\u00a0\u00a0# Code to execute if condition is False<\/pre><\/div>\n\n\n\n
for number in range(3):\n \u00a0\u00a0\u00a0if number == 1:\n \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0pass\u00a0 # Placeholder\n \u00a0\u00a0\u00a0else:\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0print(number)<\/pre><\/div>\n\n\n\n