C sharp help

What you have listed above are datatypes. If your question is which datatype to use when, the main thing to know is how much space each datatype takes and what the types are. For example, a double would be used if you need a numeric value with decimal places where an int would be used for whole numbers. Other examples of choices would be between a short, int, or uint. Short and int would both allow for whole integers, but a short takes up half the space of an int. The tradeoff you get is that a short will only allow values from -32k to 32k where an int will allow values from like -2 billion to 2 billion. The difference between the uint and int is that the uint will only take positive numbers but give you a range from 0 to 4 billion. Rule of thumb is use what you can get away with. In a classroom environment, I am sure the teacher would want you to pick the minimum size value needed to satisfy the scope of the requirement. There are similiar differences between values like ushort and short (the u is for unsigned). char and string are your literals where char is one character and string is n characters.

Hope that helps.