ArrayIteration

Question 1

What is the syntax for a while loop?

Answer 1

A while statement has the following syntax:

while(condition) {
statement(s);
}

● If the condition is true, the while loop executes the statement(s).
● Then the condition is evaluated again. If it is still true, the while loop executes the statement(s) again.
● This continues until the condition evaluates to false. If it’s never true, it never executes.

Question 2

What is the syntax for a do while loop?

Answer 2

do {
statement(s);
} while(condition);

The statement(s) are executed once first and then the condition is evaluated.
● If the condition is true, the statement(s) are executed again.
● This continues until the condition is false.
● This is also often called a do loop.

Question 3

What is the syntax for a for loop?

Answer 3

for(initialize; condition; modify) {
statement(s);
}

The initialization section can be used to declare a variable.
If a variable already exists, it can be left blank (;).
In fact, any of the parts of the for loop header may be left blank.
○ e.g. for(;;){}
● Like a while loop, the condition is tested before executing the statement(s) in the body.
○ If initially false, the statement(s) are never executed.

Question 4

What is an array?

Answer 4

Fixed length data structure.
Data in the array is accessed via index.
Initialized with null or 0.

Question 5

What is the for each loop?

Answer 5

To iterate over an array.

for(int i : numbers) {
System.out.println( i );
}
This kind of loop only works with iterable types, including arrays.

Question 6

How do you initialize and access a 2-D Array?

Answer 6

int[][] table= new int[3][5];
int value = table[2][3];

Question 7

How do you iterate through a 2-D Array?

Answer 7

Nested for loop.

for(int row=0; row<array.length; row++) {
for(int col=0; col<array[row].length; col++) {
System.out.print(array[row][col]);
}
}
One loop iterates over the rows, each
of which is an array of values…
…the nested loop iterates over each
column in the row.
Both indices are needed to retrieve a
value from the array.