Single-Branch Selection

Executes a statement or block if a condition evaluates to true.

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

Example: Check if a number is positive.

int number = 10;
if (number > 0) {
    // This block will run
}

Dual-Branch Selection

Provides an alternative path when the initial condition is false.

if (condition) {
    // Code for true case
} else {
    // Code for false case
}

Example: Determine if a number is even or odd.

int value = 7;
if (value % 2 == 0) {
    // Even
} else {
    // Odd
}

Multi-Branch Selection

Chains multiple conditions to handle several cases.

if (condition1) {
    // Case 1
} else if (condition2) {
    // Case 2
} else {
    // Default case
}

Switch Statement

Evaluates an integer expression and jumps to a matching case label.

switch (expression) {
    case constant1:
        // Code for case 1
        break;
    case constant2:
        // Code for case 2
        break;
    default:
        // Code if no case matches
}

The break statement prevents fall-through to subsequent cases.

While Loop

Repeats a block of code as long as a condition remains true. The condition is checked before each iterration.

while (condition) {
    // Loop body
}

Example: Summing integers from 1 to 5.

int idx = 1, total = 0;
while (idx <= 5) {
    total += idx;
    idx++;
}

For Loop

A compact loop structure combining initialization, condition, and update.

for (init; condition; update) {
    // Loop body
}

Example: Print numbers from 0 to 4.

for (int i = 0; i < 5; i++) {
    // Print i
}

Do-While Loop

Executes the loop body once before checking the condition. Ensures the body runs at least once.

do {
    // Loop body
} while (condition);

Example: Read input until a sentinel value is entered.

int input;
do {
    // Read input
} while (input != -1);

Loop Control Statements

• break: Immediately exits the innermots loop.
• continue: Skips the remainder of the current iteration and proceeds to the next one.

Clearing Input Buffer

A common pattern to discard remaining characters in the input buffer.

int ch;
while ((ch = getchar()) != '\n' && ch != EOF);