I created a coding diary blog to share my progress with you. We started the first day with c# course.

10/11/2021 notes

Firstly, we started with variables and types of variables. Defining a variable is not rocket science. I'll show you how to define a varible and assign it a value; for instance, we specify the type and asign it a value. 

int num = 10;
string helloWorld = "Hello World!";
double thisIsADouble = 42.42d;

Data types: char, string, decimal, float, double, sbyte, float…
Here is a short version of data types table:

Type Ranger
int -2,147,483,648 to 2,147,483,647
byte 0 to 255
sbyte -128 to 127
short -32,768 to 32,767
double -1.79769313486232E+308 to 1.79769313486232E+308

We find their max and min value using MaxValue and MinValue.

sbyte num = -45;
num = 45;
byte byteMaks = byte.MaxValue;
byte byteMin = byte.MinValue;

Console.WriteLine($"The largest value of the byte type: {byteMaks}");
Console.WriteLine($"The smallest value of the byte type: {byteMin}");

short shortSayiMaks = short.MaxValue;
short shortSayiMin = short.MinValue;

long longMaks = long.MaxValue;
long longMin = long.MinValue;

double doubleNum = double.MaxValue;
Console.WriteLine($"The largest value of the double type = {doubleNum}");

To learn the type of a variable use GetType() method; for instance, x.GetType().

var x= 55;
var y =34.23d; 

Console.ReadLine() //  get user inputs.

Reference Type

These reference types hold a reference to the location of the data. if you change the variable value, the latest value is your new variable value. String and string are not the same things. String: create String Object string: data type. When you define a value using var, it retains the first attributed value type.

Arithmetic Operators

+, -, *, /, %, ++, – </b>

int a, b, c, d, result;
a = 2;b = 3; c = 4; d = 6;
result = a+b*(c+d)-a;
Console.WriteLine($"Result:{result}")

Logical Operators

Logical Or Operator : ||
Logical And Operator : &&
Logical Not Operator :!

Bitwise Operators

They work on bits.The table below show you why num1 & num2;// => 0001

& 0 1
0 0 0
1 0 1 


byte num1 = 5; //0101
byte num2 = 3; //0011
int control7 = num1 & num2;// =>    0001
int control8 = num1 | num2;// =>    0111
byte control9 = (byte)~num2;
Console.WriteLine(control7);
Console.WriteLine(control8);
Console.WriteLine(control9);

Type conversions

Here, we are converting a type to an other type. To give an example, we can convert an integer to a float.

int num = 305;
byte byteNum = (byte)num;
byte byteNum2 = Convert.ToByte(num)

11/11/2021

int intNum = 256;
byte byteNum = (byte)intNum; // takes the rightmost 8 bits 
Console.writline($"byte number: {byteNum}");

To avoid loses during type casting, we used checked{}.

checked{
    int intNum = 256;
    byte byteNum = (byte)intNum;// takes the rightmost 8 bits 
    Console.writline($"byte number: {byteNum}");

    unchecked{
        int ıntNum2 = 256;
        byte =byteNum = (byte)intNum2 // even we lose some bites, casting does not stop.
    }

}

Type casting with Parse method

Here, we are parsing strings and convert them to an int, double and short.

int variable1 = int.Parse("365");
double variable2 = double.Parse("34");
short variable3 = short.Parse("4321");

Boxing and Unboxing

Object is the base class for all derived classes

Boxing

This is the process of converting a value type to an object.

int limit = 120;
object box = limit;

Boxing with type conversion

object box2 = (object)limit;

Unboxing

To unboxe an object, it should be boxed and object type should be the same as the taget type.

float floatNum = 94.5f;

Boxing

object obj = floatNum ;

Unboxing

floatNum = (float)obj;