A C# array variable is declared similarly to a non-array variable, with the addition of square brackets ([]) after the type specifier to denote it as an array.

The new keyword is needed when instantiating a new array to assign to the variable, as well as the array length in the square brackets. The array can also be instantiated with values using curly braces ({}). In this case the array length is not necessary.

In C#, one way an array can be declared and initialized at the same time is by assigning the newly declared array to a comma separated list of the values surrounded by curly braces ({}). Note how we can omit the type signature and new keyword on the right side of the assignment using this syntax. This is only possible during the array’s declaration.

In C#, the elements of an array are labeled incrementally, starting at 0 for the first element. For example, the 3rd element of an array would be indexed at 2, and the 6th element of an array would be indexed at 5.

A specific element can be accessed by using the square bracket operator, surrounding the index with square brackets. Once accessed, the element can be used in an expression, or modified like a regular variable.

The Length property of a C# array can be used to get the number of elements in a particular array.

A C# for loop executes a set of instructions for a specified number of times, based on three provided expressions. The three expressions are separated by semicolons, and in order they are:

• Initialization: This is run exactly once at the start of the loop, usually used to initialize the loop’s iterator variable.
• Stopping condition: This boolean expression is checked before each iteration to see if it should run.
• Iteration statement: This is executed after each iteration of the loop, usually used to update the iterator variable.

A C# foreach loop runs a set of instructions once for each element in a given collection. For example, if an array has 200 elements, then the foreach loop’s body will execute 200 times. At the start of each iteration, a variable is initialized to the current element being processed.

A for each loop is declared with the foreach keyword. Next, in parentheses, a variable type and variable name followed by the in keyword and the collection to iterate over.

In C#, a while loop executes a set of instructions continuously while the given boolean expression evaluates to true or one of the instructions inside the loop body, such as the break instruction, terminates the loop.

Note that the loop body might not run at all, since the boolean condition is evaluated before the very first iteration of the while loop.

The syntax to declare a while loop is simply the while keyword followed by a boolean condition in parentheses.

In C#, a do while loop runs a set of instructions once and then continues running as long as the given boolean condition is true. Notice how this behavior is nearly identical to a while loop, with the distinction that a do while runs one or more times, and a while loop runs zero or more times.

The syntax to declare a do while is the do keyword, followed by the code block, then the while keyword with the boolean condition in parentheses. Note that a semi-colon is necessary to end a do while loop.

An infinite loop is a loop that never terminates because its stopping condition is always false. An infinite loop can be useful if a program consists of continuously executing one chunk of code. But, an unintentional infinite loop can cause a program to hang and become unresponsive due to being stuck in the loop.

A program running in a shell or terminal stuck in an infinite loop can be ended by terminating the process.

Jump statements are tools used to give the programmer additional control over the program’s control flow. They are very commonly used in the context of loops to exit from the loop or to skip parts of the loop.

Control flow keywords include break, continue, and return. The given code snippets provide examples of their usage.