Nested Statements (CIE IGCSE Computer Science)

• Nested statements involve including one statement within another statement. This can be done with both selection (if/else) and iteration (for/while) statements
• In programming languages like Python, Java, and Visual Basic, nested statements are often indicated by indenting the inner statement(s) relative to the outer statement(s)

• Nested selection is an if statement inside an if statement
• If the first if statement is true, it will run the if statement which is nested inside
• Otherwise, it will skip to the "else if" or "else" which is part of that if statement

Pseudocode example:

if a > b then

    if b > c then

        output “a is the largest”

    else

        output “c is the largest”

else

    if a > c then

        output “b is the largest”

    else

        output “c is the largest”

Python example:

if a > b:

    if b > c:

        print("a is the largest")

    else:

        print("c is the largest")

else:

    if a > c:

        print("b is the largest")

    else:

        print("c is the largest")

Java example:

if (a > b) {

if (b > c) {

System.out.println("a is the largest");

} else {

System.out.println("c is the largest");

}

} else {

if (a > c) {

System.out.println("b is the largest");

} else {

System.out.println("c is the largest");

}

}

Visual Basic example:

If a > b Then

If b > c Then

Console.WriteLine("a is the largest")

Else

Console.WriteLine("c is the largest")

End If

Else

If a > c Then

Console.WriteLine("b is the largest")

Else

Console.WriteLine("c is the largest")

End If

End If

Nested iteration refers to a loop inside another loop.

Pseudocode example:

FOR i ← 1 TO 10

    FOR j ← 1 TO 5

        OUTPUT "i = ", i, " j = ", j

    END FOR

END FOR

Python example:

for i in range(1, 11):

    for j in range(1, 6):

        print("i = ", i, " j = ", j)

Java example:

for (int i = 1; i <= 10; i++) {

    for (int j = 1; j <= 5; j++) {

        System.out.println("i = " + i + " j = " + j);

    }

}

Visual Basic example:

For i As Integer = 1 To 10

    For j As Integer = 1 To 5

        Console.WriteLine("i = " & i & " j = " & j)

    Next j

Next i