Programming 1 Cheat Sheet

A Programming › C cheat sheet in English by programming1

Sept-Dec, Introduction to C#

C-

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PRs

Variable types

	Page 35
A variable stores a value during the running of a program
Type	Description
string	contains alpha numeric characters, persons name
int	a number value without decimal points, persons age
double	a number with decimal points, an amount of money
boolean	either true or false

c# is a strongly typed language. All variables must have a type.
We cannot "mix" types.

Simple Print to Console

	Page 45
Examples Console.WriteLine("Hello World"); Console.Write("and Hello Moon");
Line	Description
1	insert a carriage return and leave cursor on next line
2	leave cursor on same line

Placeholders

	Page 49
$"{varName1} {varName2}"
Examples Console.WriteLine(${"Name : {studentName}"); Console.WriteLine($"GPA : {studentGpa}");
Line	Description
1	{ and } enclose the variable name to display

You can use multiple placeholders in one string.

Logical operators

	Page 62
Operand	Description
A==B	checks two operands to see if equal. false
A!=B	check operands to see if not equal. true
A<B	is A less than B? false
A>=B	is A greater than or equal to B. true
A<=B	is A less than or equal to B? false

An operand is variable or value involved in operation. In examples above - A=10, B=5

Loops - While Loop

Pages 79-83,86-87

/
loop through a statement block 10 times
if condition is not satisfied, statements will not be executed
/
int counter=0;
while (counter <=10)
{
Console.WriteLine($"Counter value is {counter}");
counter ++;
}

Methods - declaration

	Page 93
[static] [public\|private] return-type MethodName ([param-list]}
Type	Description
[static]	no need to create instance, call directly
[public \| private]	can only be called from within this class
[void \| int \| double \| string]	return type, void infers nothing returned
MethodName	use PascalCase for naming the method
([param-list])	specify paramater type, separate with commas

Tips n' Tricks for CA #1

Tip	Reason
Comment your code	allows you or someone else to more easily understand the code now or in the future
Watch your variables and constant naming convention	Use camelCase for ordinary variables, and UPPERCASE for constants - it's easy then to tell them apart

Variable Definition & Assignment

	Pages 43-45
[type] <varName> = <value>;
Examples int studentAge=19; string studentName="Walter"; double studentGpa=78.68; boolean studentRegistered;
Item	Description
type	common types int, string, double, boolean
<varName>	the name of variable in which we store value

studentRegisterd is not initialised at declaration time above. it could be true or false.

Read Keyboard Input - Strings

	Page 54
Example studentName=Console.ReadLine();
Line	Description
1	read input from keyboard, assign to studentName

Console.ReadLine() is a method without parameters.
It takes input from the keyboard as a string

Common Formatting Codes

		Page 58-59
$"{x:c} {y:p} {z:n3}"
Code	Format	Output
C or c	currency	€1,245.44
P or p	percent	4.00%
N or n	Number	103,423.346

Formatting improve the output for the user.

Above x=1245.443, y=0.04 and z=103423.3456.

If stements - combining expressions

Page 64-65

if ((condition1 && condtion2)
{
// execute if condition1 AND condition2 true
}
else if ((condition3 II condtion4)
{
// execute if condition3 OR condition4
}
else
// then execute this statement

Loops - Do While

Page 84

/
loop through a statement block 10 times
statement block will always execute at least once
even if counter was initially 11!!
*/
int counter=0;
do
{
Console.WriteLine($"Counter value is {counter}");
counter ++; //
} while (counter <=10)

Methods - related terminology

	Page 92
Item	Description
return type	a method can return a value - of type int, double, string. if nothing returned, then return-type is void
sharing data between methods	parameters - values passed to a method call. also known as arguments. class level variables - available to all methods, scope is global
calling a method	We must call the method to invoke it.
predefined methods	Includes Console.WriteLine("Hello) - has parameters Console.Readline() - no parameters

Tips n' Tricks for CA #2

Tip	Reason
Use code indentation	When using conditional (If), Loops (While, Do While, For) and Methods - indent your code. Make it easier to read for everyone.
Follow the recipe	Make your input and output actually look like what is presented on the CA question.

Using naming conventions, comments

	Pages 39,53,93,30
Type	Description
variables	camelCase, first letter is lowercase, other words first letter uppercase
constants	use uppercase, e.g. VATRATE
methods	PascalCase, first letter of each word is uppercase
comment our code	// what does this code do? /* reminds colleagues, our future selves */

Coding conventions are important within a team.

It is part of the common language of writing software code.

Read Keyboard input - Numbers

	Page 55
Example studentAge = int.Parse(Console.ReadLine()); studentGrade = double.Parse(Console.ReadLine());
Line	Description
1	Integer value is returned and assigned
2	Double value may contain decimals

Extract a number from the keyboard input with .Parse()

Neater Printing in Tables

	Page 57
$"<text>{<expression>,<field-width>}<text>..."
Examples
$"Name :{studentName,20}"
$"{"Name",-20} :{studentName}"
Line	Description
1	right justify, 20 leading spaces before student name
2	left justify, 20 spaces after label "Name"

If statements - Examples

Pages 66-73

if (studentGpa>=70)
{
Console.WriteLine("Honours");
}
else if (studentGpa<70 && studentGpa>=50)
{
Console.WriteLine("Distinction");
}
else Console.WriteLine("Fail");

Loops - For Loop

Pages 85,87

/
initial value of counter set in for statement
counter is incremented then statement block complete
/
int counter;
for (counter=0; counter <=10; counter++)
{
Console.WriteLine($"Counter value is {counter}");
}

Methods - full example

class Program
{
 static void Main(string[] args)
 {
  static string salutation="Hello"; 
  string name=GetName();
  PrintGreeting(name);
 } 

 static private string GetName() 
 {
   Console.WriteLine("Enter First Name : ");
   string firstName=nameConsole.ReadLine();
   return firstName;
 }
static private void PrintGreeting(string name)
 {
  Console.WriteLine($"{salutation} {name}!");
 }
}} // end class

Bits and pieces

Console.OutputEncoding=System.Text.Encoding.UTF8; // display special symbols like currency

Carriage Return or "\n" // A carriage return moves the cursor onto the next line in our console display.

Lab worksheet is a solution. Each question is a project

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