Control Statements in Programming

Control statements decide how code runs, how many times it runs, and which path it follows.

There are 3 main types:

1. Decision Making (Conditions)

2. Loops (Repetition)

3. Jump Statements (Flow control)

Examples use Java-style syntax, but the logic is similar in most languages.

1) Decision Making Statements

These run code based on conditions (true/false).

if statement
Runs code only if condition is true.

Syntax:

if (condition) {
    // code to execute
}

Example:

int age = 18;

if (age >= 18) {
    System.out.println("You are eligible to vote.");
}

if–else statement
Chooses between two blocks.

Syntax:

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

Example:

int number = 5;

if (number % 2 == 0) {
    System.out.println("Even number");
} else {
    System.out.println("Odd number");
}

if–else if ladder
Checks multiple conditions.

Syntax:

if (condition1) {
    // block 1
} else if (condition2) {
    // block 2
} else {
    // default block
}

Example:

int marks = 75;

if (marks >= 90) {
    System.out.println("Grade A");
} else if (marks >= 60) {
    System.out.println("Grade B");
} else {
    System.out.println("Grade C");
}

switch statement
Used when comparing one variable with many values.

Syntax:

switch (variable) {
    case value1:
        // code
        break;
    case value2:
        // code
        break;
    default:
        // code if no match
}

Example:

int day = 2;

switch (day) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    default:
        System.out.println("Invalid day");
}

2) Looping Statements (Repetition)

Used to repeat code multiple times.

for loop
Best when number of repetitions is known.

Syntax:

for (initialization; condition; update) {
    // code
}

Example:

for (int i = 1; i <= 5; i++) {
    System.out.println(i);
}

while loop
Runs while condition is true.

Syntax:

while (condition) {
    // code
}

Example:

int i = 1;

while (i <= 5) {
    System.out.println(i);
    i++;
}

do–while loop
Runs at least once, then checks condition.

Syntax:

do {
    // code
} while (condition);

Example:

int i = 1;

do {
    System.out.println(i);
    i++;
} while (i <= 5);

for-each loop
Used with arrays/collections.

Syntax:

for (datatype variable : array) {
    // code
}

Example:

int[] numbers = {10, 20, 30};

for (int num : numbers) {
    System.out.println(num);
}

3) Jump Statements

Used to change loop flow.

break → stops loop
continue → skips current iteration
return → exits method

Example:

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue; // skips 3
    }
    System.out.println(i);
}