The if statement executes code only when a condition is true.

Syntax (C and Python)

In C:

if (condition) {
    // code to execute if condition is true
}

In Python:

if condition:
    # code to execute if condition is true

Example

A program that checks if a student passed an exam:

Python:

score = 75

if score >= 50:
    print("You passed the exam!")

C:

int score = 75;

if (score >= 50) {
    printf("You passed the exam!\n");
}

In both examples, the message prints only when the score is 50 or more.

The if-else statement provides two paths: one when the condition is true, another when it is false.

Syntax (C and Python)

In C:

if (condition) {
    // code if true
} else {
    // code if false
}

In Python:

if condition:
    # code if true
else:
    # code if false

Example

Checking if a number is positive or negative:

Python:

number = -5

if number >= 0:
    print("The number is positive or zero.")
else:
    print("The number is negative.")

Output: The number is negative.

C:

int number = -5;

if (number >= 0) {
    printf("The number is positive or zero.\n");
} else {
    printf("The number is negative.\n");
}

When there are more than two possible outcomes, we use the else-if ladder (or elif in Python).

Syntax (C and Python)

In C:

if (condition1) {
    // code for condition1
} else if (condition2) {
    // code for condition2
} else {
    // code if none are true
}

In Python:

if condition1:
    # code for condition1
elif condition2:
    # code for condition2
else:
    # code if none are true

Example: Grading System

A program that assigns grades based on marks:

Python:

marks = 72

if marks >= 80:
    print("Grade: A")
elif marks >= 60:
    print("Grade: B")
elif marks >= 40:
    print("Grade: C")
else:
    print("Grade: F")

Output: Grade: B

C:

int marks = 72;

if (marks >= 80) {
    printf("Grade: A\n");
} else if (marks >= 60) {
    printf("Grade: B\n");
} else if (marks >= 40) {
    printf("Grade: C\n");
} else {
    printf("Grade: F\n");
}

We often need to check multiple conditions together. The logical operators are:

Example: Voting Eligibility

A person can vote if they are 18 or older and are a citizen.

Python:

age = 20
is_citizen = True

if age >= 18 and is_citizen:
    print("You are eligible to vote.")
else:
    print("You cannot vote.")

Output: You are eligible to vote.

C:

int age = 20;
int is_citizen = 1;  // 1 means true, 0 means false

if (age >= 18 && is_citizen) {
    printf("You are eligible to vote.\n");
} else {
    printf("You cannot vote.\n");
}

A shop in Dar es Salaam gives discounts based on purchase amount:

• TZS 10,000 or more: 10% discount
• TZS 5,000 to 9,999: 5% discount
• Below TZS 5,000: no discount

Python:

amount = int(input("Enter purchase amount (TZS): "))

if amount >= 10000:
    discount = amount * 0.10
    final_price = amount - discount
    print(f"Discount: TZS {discount}")
    print(f"Final price: TZS {final_price}")
elif amount >= 5000:
    discount = amount * 0.05
    final_price = amount - discount
    print(f"Discount: TZS {discount}")
    print(f"Final price: TZS {final_price}")
else:
    print("No discount applied.")
    print(f"Final price: TZS {amount}")

If the user enters 8000, the output is:

Discount: TZS 400.0
Final price: TZS 7600.0

1. Forgetting to indent in Python – indentation defines which code belongs to which branch
2. Using single = instead of == – = assigns a value, == compares values
3. Forgetting parentheses in C – conditions must be inside ( )
4. Not handling all cases – always consider what happens when no condition is true

In Tanzania, branching is used in mobile money systems like M-Pesa. When you buy airtime, the system checks if you have enough balance; if yes, it processes the transaction and deducts the amount, otherwise it displays an error message. Similarly, when applying for a loan through mobile banking, the system uses branching to check your age, income, and existing balance before deciding whether to approve or reject your request.