Operator Shorthand

Incrementing the value of a variable is a pretty common occurrence, and there are a way different ways we can do so. Here are a few different examples, all which result in window_count increasing in value by 1.

window_count = window_count + 1;
window_count += 1;
window_count++;     // this means "give me the value THEN add 1"
++window_count;     // this means "add 1 THEN give me the value

Be very careful with the two variations of ++. For example, here:

int i = 2, j;
j = ++i;           // j has the value of 3

Please note: i and j are terrible variable names. You should use something more descriptive in your actual code.

Pre-test loops

These are loops where the test happens before the process, so the process can execute 0 or more times.

while loops

We generally use while loops for loops that are controlled by some condition.

Syntax:

while (boolean expression) {
	// statements
	// including something to prevent an infinite loop!
}

For example, maybe we have a segment of code that is filling something, and we want to iterate until our container is full:

bool isFull = false;
while (!isFull) { // this is the same as: while (isFull == false)
    ...
    // code to conditionally set isFull to true
    ...
} // end while

We will keep iterating through the loop until something sets isFull to true.

for loops

for loops are best used when we (or the user) know how many times we will iterate through our loop.

Syntax:

for (initalize; test; modify)
	process;

• There may be zero, one, or multiple initializations, separated by commas
• There may be only one test (although it can be compound using && or ||)
• There may be zero, one, or multiple modifications, separated by commas
• There may be many process statements if braces are used

For example, we can translate this while loop into a for loop:

int count = 10;
while (count > 0) {
    Console.WriteLine(count);
    count--;
} // end while

for (int count = 10; count > 0; count--) {
    Console.WriteLine(count);
} // end for

Both of these have the same output.

Post-test loops

The test happens after the process, so the process will always execute at least once:

do-while loops

We’ll use a do while loop if we know the code in our loop needs to execute at least one time.

Syntax

do {
    // process
} while (test_condition) ;

For example:

long num, nFactorial, count;
char response;
Console.WriteLine("Welcome to the factorial calculator!");

do {
    Console.Write("Enter positive n value: ");
    num = long.Parse(Console.ReadLine());

    if (num >= 0)
    {
        nFactorial = 1;
        count = num;
        for (count = num; count > 1; count--)
            nFactorial *= count;
        Console.WriteLine($"N = {n}, N! = {nFactorial}");
    } // end if
    else
    {
        Console.WriteLine("ERROR: N must be at least 0.");
    } // end else

    Console.WriteLine("Enter 'Y' to continue or 'N' to exit.");
    response = char.Parse(Console.ReadLine());
} while (response == 'Y' || response == 'y');

Console.WriteLine("Thanks, please come again.");