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($"GPA : {studentGpa}"); |
Line |
Description |
1 |
{ and } enclose the variable name to display |
You can use multiple placeholders in one string.
Logical operators
| |
Page 62 |
Operand |
Description |
A==B |
checks two operands to see if equal. false |
A!=B |
check operands to see if not equal. true |
A<B |
is A less than B? false |
A>=B |
is A greater than or equal to B. true |
A<=B |
is A less than or equal to B? false |
An operand is variable or value involved in operation. In examples above - A=10, B=5
Loops - While Loop
/*
* loop through a statement block 10 times
* if condition is not satisfied, statements will not be executed
*/
int counter=0;
while (counter <=10)
{
Console.WriteLine($"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 |
$"{x:c} {y:p} {z:n3}" |
Code |
Format |
Output |
C or c |
currency |
€1,245.44 |
P or p |
percent |
4.00% |
N or n |
Number |
103,423.346 |
Formatting improve the output for the user.
Above x=1245.443, y=0.04 and z=103423.3456.
If stements - combining expressions
if ((condition1 && condtion2)
{
// execute if condition1 AND condition2 true
}
else if ((condition3 II condtion4)
{
// execute if condition3 OR condition4
}
else
// then execute this statement
Loops - Do While
/*
* loop through a statement block 10 times
* statement block will always execute at least once
* even if counter was initially 11!!
*/
int counter=0;
do
{
Console.WriteLine($"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}" |
$"{"Name",-20} :{studentName}" |
Line |
Description |
1 |
right justify, 20 leading spaces before student name |
2 |
left justify, 20 spaces after label "Name" |
If statements - Examples
if (studentGpa>=70)
{
Console.WriteLine("Honours");
}
else if (studentGpa<70 && studentGpa>=50)
{
Console.WriteLine("Distinction");
}
else Console.WriteLine("Fail");
Loops - For Loop
/*
* initial value of counter set in for statement
* counter is incremented then statement block complete
*/
int counter;
for (counter=0; counter <=10; counter++)
{
Console.WriteLine($"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 |
|
Created By
Metadata
Comments
No comments yet. Add yours below!
Add a Comment
Related Cheat Sheets