lecture 2 review of 1301 and c# richard gesick. common data types int, long, double, float, char,...
DESCRIPTION
To declare a variable ; Example: int myNum; You can also initialize it when you delcare it: int myNum = 42; string myString="josh";TRANSCRIPT
Lecture 2
Review of 1301 and C#
Richard Gesick
Common data types
int, long, double, float, char, bool, string
To declare a variable <type> <name>;Example:int myNum;You can also initialize it when you delcare it:int myNum = 42;string myString="josh";
Console I/O Console.Write(X);Console.WriteLine(X);string A = Console.ReadLine();
Note that ReadLine() returns a string, so if you want to get something else from the user (and int for example), you would have to convert it. For 1302, you may assume the user will give valid input, but later in the course we will explore exception handling.
Conversion int myNum = Int32.Parse(Console.ReadLine());
This takes in input from the user (as a string) and then passes this string to the Parse method of the Int32 class; this Parse method returns an int, so this is a valid assignment since now the left and the right side of the assignment (=) operator are of the same type.
User interactionstring name;Console.Write("What is your name? ");name = Console.ReadLine();Console.WriteLine("Hello " + name);
Notice in the above that the + operator acts as string concatenation.
ConditionalsConsole.Write("How old are you? ");int age = Int32.Parse(Console.ReadLine());
if (age < 18) Console.WriteLine("You cannot drink or vote.");else if (age < 21) Console.WriteLine("You can vote but not drink.");else Console.WriteLine("You can vote and drink, but
don't vote shortly after drinking!");
{ }Notice in the previous that we don't have to use curly-brackets to define the block in the if-else because we only want to control one line of code, but if you wanted to do more than one statement, use { } to mark the body of the if-else statement blocks.
Declaring Methods You declare a method in C# using the following pattern:<return type> <name> (<parameter(s)>){ <body of method>}
Method examples 1 a menu
void PrintMenu(){ Console.WriteLine("1. Display result"); Console.WriteLine("2. Add a number"); Console.WriteLine("3. Delete a number"); Console.WriteLine("4. QUIT");}
Method examples 2 choice
int GetChoice(){ int choice; do { Console.Write("Enter your choice (1-4) : "); choice = Int32.Parse(Console.ReadLine()); } while ((choice < 1) || (choice > 4)); return choice;}
for loops
for(<initialize>; <conditional>; <post-activity>){ <body/work>}
for ( int i=0; i < 100; i += 2){ Console.WriteLine(i);}
do while loop
do { <body/work>} while (<conditional>);
int i = 10;do { Console.WriteLine(i); i--;} while (i > 0);
while loop
while (<conditional>){ <body/work>}
int i = 0;while (i != 0){ Console.WriteLine(i); i -= 1;}