public class CompSci{

}

All C# programs start with a class.

public class CompSci{ public static void Main(String[] args) { Console.WriteLine("Comp Sci!"); }} OUTPUT

Comp Sci!

public class CompSci{ //open brace

public static void Main(String[] args) { Console.WriteLine ("Comp Sci!"); }} //close brace

Braces – You gotta have ‘em! Every classand every method must have a { and a } .

public class CompSci{ public static void main(String[] args) { Console.WriteLine("Comp Sci!"); }}You must put a semi-colon at the end of all C# program statements ( ; ).

Never put a ; before an open { brace

;{ //illegal}; //legal

public class CompSci{ public static void Main(String[] args) { Console.WriteLine("Comp Sci!"); }}

Indent all code 3 spaces to make it easier to read.

Console.frequently used methods

Name UseConsole.Write print x and stay on the current line

Console.WriteLine

print x and move to next line down

Console.Write("compsci");

reference command / method

OUTPUTcompsci

Console.Write("compsci");Console.Write("compsci");

OUTPUTcompscicompsci

Console.WriteLine("compsci");

OUTPUTcompsci

Console.WriteLine("compsci");Console.WriteLine("compsci");

OUTPUTcompscicompsci

Console.WriteLine("c\tompsci");

\n newline\t tab\r carriage return\b backspace

OUTPUTc ompsci

Console.WriteLine("com\tpsci");

OUTPUTcom psci

\n newline\t tab\r carriage return\b backspace

Console.WriteLine("comp\nsci");

OUTPUTcompsci

\n newline\t tab\r carriage return\b backspace

\\ outs \\" outs "\’ outs ’

Console.WriteLine("\\compsci\"/");

OUTPUT\compsci"/

\\ outs \\" outs "\’ outs ’

Console.WriteLine("\\'comp\'sci\'/");

OUTPUT\'comp'sci'/

Escape Sequencesfrequently used combinations

Name Use

\t tabs over five spaces

\n moves to front of next line

\b deletes previous character

\r moves to front of current line

\\ nets one backslash \

\" nets one double quote "

\’ nets one single quote ’

// single-line comments/* */ block comments

//this line prints stuff on the screenConsole.WriteLine("stuff");

// single-line comments/* */ block comments

/* this line prints stuff on the screen*/Console.WriteLine("stuff");

Syntax errors occur when you type something in wrong, causing the code to not compile.

//missing semicolon - ; expectedConsole.WriteLine("stuff")

//case problem – should be SystemConsole.WriteLine("stuff")

Runtime errors occur when something goes wrong while the program is running.

//an out of bounds exception is thrownString s = "runtime_error";Console.WriteLine( s[15] );