C# CheatSheet Cheat Sheet

A Programming › Nope cheat sheet in English by pao361

programming code, basics

15,857 views 2,423 downloads 8 Jan 2022 History

PRs

Data Types

string	2 bytes/char
bool
char	2 bytes
byte	1 byte
short	2 bytes
int	4 bytes
long	8 bytes
float	4 bytes
double	8 bytes
decimal	16 bytes

Float: Can hold up to seven significant digits of accuracy
Double: Can hold 15 or 16 significant digits of accuracy
Decimal: Has a greater precision and a smaller range. Suitable for financial and monetary calculations

Displaying Variable Values

using System;
public class DisplaySomeMoney
[
       public static void Main()
       {
              double someMoney = 39.45;
              Console.WriteLine(someMoney);
        }
[

Operators

+	Addition	-	Subtraction
*	Multiplication	/	Division
%	Remainder

Suffixes

Put an F after a number to make it a float
float pocketchange = 4.87F;
Put a D after it to make it a double (default)
float pocketchange = 4.87D;
Put an M (money) after it to make it a decimal
float pocketchange = 4.87M;
Scientific notation
Includes an E (for exponent)

Methods

Define it – takes 4 steps
Declaration (or method header, or signature)
{
Code (method body)
Return value;
}

Call it (invoke it)

Method declarations

Method with no return value, and passes no parameters
public static void DisplayHelloText()
DisplayHelloText();

Method with no return value, and passes one parameter
public static void DisplaySalesTax(double pAmt)
DisplaySalesTax(1243.00);

Method with no return value, and passes two parameters
public static void DisplaySalesTax(double pAmt, double ptaxRate)
DisplaySalesTax (1243.00, .09);

Method that returns a value, and passes two parameters
public static double DisplaySalesTax(double pAmt, double ptaxRate)
Amount = DisplaySalesTax (1243.00, .09);
return Answer;

(if no return, then void, else, return type, e.g. integer32, string, double, etc)

Convert Methods

ToBoolean()	to an equivalent Boolean value	ToInt16()	to a 16-bit signed integer
ToByte()	to an 8-bit unsigned integer	ToInt32()	to a 32-bit signed integer
ToChar()	to a Unicode character	ToInt64()	to a 64-bit signed integer
ToDecimal()	to a decimal number	ToString()	to its equivalent String representation
ToDouble()	to a double-precision floating-point number	ToUInt16()	to a 16-bit unsigned integer

Arrays Functions

Array.Sort(arrayName)	Arranges array items in ascending order
Array.Length	Length of the array
Array.Reverse(arrayName)	Reverses the order of items in an array
Array.BinarySearch(ArrayName, value)	Finds a requested value in a sorted array

Do not use BinarySearch() under these circumstances
If your array items are not arranged in ascending order
If your array holds duplicate values and you want to find all of them
If you want to find a range match rather than an exact match

Array

Assigning values to array elements
double[] sales = new double[20];
sales[0] = 2100.00;
sales[1] = 3256.06;
Printing an element value
Console.WriteLine(sales[1]);

*for loop to search a Parallel Array
for (int i = 0; i < nameArray.Length; i++)
{
if (nameArray[i] == dwarfName)
{
do something*
}
}

Multidimensional Arrays

One-dimensional or single-dimensional array	Picture as a column of values. Elements can be accessed using a single subscript
Multidimensional arrays	Require multiple subscripts to access the array elements

Conditional Operators

Conditional AND operator
-Determines whether two expressions are both true
-Written as two ampersands (&&)
-You must include a complete Boolean expression on each side of the operator
Written as If (age >= 0 && age < 120)

Conditional OR operator
Used when you want some action to occur even if only one of two conditions is true
Written as if (a == 1 || b+c > 3)

Loops

if stataments
if (statement)
{
do something
}

while loop
while (statement)
{
do something
}//end loop

-Definite loop or counted loop
Loop for which the number of iterations is predetermined
-Indefinite loop
Value of a loop control variable is not altered by arithmetic, but instead, is altered by user input (ask user a question inside the loop, exit based on a particular answer)

do-while loop
do
{
do something in the loop
}
while (statement)

for loop
When using a for statement, you can indicate in one place:
Starting value for the loop control variable
Test condition that controls loop entry
Expression that alters the loop control variable
for (statement)
do something

DateTime and TimeSpan

DateTime(yr, mo,day)	currdt.AddDays(1)
DateTime(yr, mo,day, hr, min, sec)	currdt.SubtractDays(1)
DateTime.Parse("1/1/2015")	TimeSpan(hrs,min,sec)
DateTime.Now	TimeSpan.FromSeconds(120)

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