Core csharp and net quick reference

Core C# and .NET
Quick Reference
1. Data Types
Primitive Size Example
string 2 bytes/char s = “reference”;
bool b = true;
char 2 bytes ch = ‘a’;
byte 1 byte b = 0x78;
short 2 bytes Ival = 54;
int 4 bytes Ival = 540;
long 8 bytes ival = 5400;
float 4 bytes val = 54.0F;
double 8 bytes val = 54.0D;
decimal 16 bytes val = 54.0M;
2. Arrays
Declaration
int[] numArray = {1903, 1907, 1910};
int[] numArray = new int[3];
// 3 rows and 2 columns
int[ , ] nums = {{1907, 1990}, {1904, 1986}, {1910, 1980}};
Array Operations
Array.Sort(numArray); // sort ascending
// Sort begins at element 4 and sorts 10 elements
Array.Sort(numArray, 4,10);
// Use one array as a key and sort two arrays
string[] values = {“Cary”, “Gary”, “Barbara”};
string[] keys = {“Grant”, “Cooper”, “Stanwyck”};
Array.Sort(keys, values);
// Clear elements in array (array, 1st
element, # elements)
Array.Clear(numArray, 0, numArray.Length);
// Copy elements from one array to another
Array.Copy(src, target, numelements);
3. String Operations
Method Description
Compare String.Compare(stra, strb, case, ci)
bool case – true for case insensitive
ci – new CultureInfo(“en-US”)
returns: <0 if a<b, 0 if a=b, 1 if a>b
IndexOf str.IndexOf(val, start, num)
val – string to search for
start – where to begin in string
num – number of chars to search
returns (–1) if no match.
LastIndexOf Search from end of string.
Replace newstr= oldstr.Replace(“old”,”new”);
Split Char[] delim= {‘ ‘, ‘,’};
string w = “Kim, Joanna Leslie”;
// create array with three names
string[] names= w.Split(delim);
6. Formatting Numeric and Date Values
Format Item Syntax: {index[,alignment] [:format string]}
index – Specifies element in list of values to which format is applied.
alignment – Indicates minimum width (in characters) to display value.
format string – Contains the code that specifies the format of the displayed value.
Example: String.Format(“Price is: {0:C2}”, 49.95); // output: Price is: $ 49.95
a. Numeric Formatting
Format
Specifier
Pattern Value Description
C or c {0:C2}, 1388.55 $ 1388.55 Currency.
D or d {0:D5}, 45 00045 Must be integer value.
E or e {0,9:E2}, 1388.55 1.39+E003 Must be floating point.
F or f {0,9:F2}, 1388.55 1388.55 Fixed Point representation.
N or n {0,9:N1}, 1388.55 1,388.6 Insert commas
P or p {0,9:P3}, .7865 78.650% Converts to percent.
R or r {0,9:R}, 3.14159 3.14159 Retains all decimal places.
X or x {0,9:X4}, 31 001f Converts to Hex
Example: CultureInfo ci = new CultureInfo("de-DE"); // German culture
string curdt = String.Format(ci,"{0:M}",DateTime.Now); // 29 Juni
b. DateTime Formatting: (January 19, 2005 16:05:20) en-US
Format Value Displayed Format Value Displayed
d 1/19/2005 Y or y January, 2005
D Wednesday, January
19, 2005
t 4:05 PM
f Wednesday, January
19, 2005 4:05:20 PM
T 4:05:20 PM
F Wednesday, January
19, 2005 4:05 PM
s 2005-01-19T16:05:20
g 1/19/2005 4:05 PM u 2005-01-19 16:05:20Z
G 1/19/2005 4:05:20 PM U Wednesday, January
19, 2005 21:05:20PM
M or m January 19
7. Using the System.Text.RegularExpressions.Regex class
string zipexp = @"d{5}((-|s)?d{4})?$";
string addr="W.44th St, New York, NY 10017-0233";
Match m = Regex.Match(addr,zipexp); // Static method
Regex zipRegex= new Regex(zipexp);
m= zipRegex.Match(addr); // Use Regex Object
Console.WriteLine(m.Value); // 10017-0233
Pattern Description Example
+ Match one or more occurrence ab+c matches abc, abbc
* Match zero or more occurrences ab*c matches ac, abbc
? Matches zero or one occurrence ab?c matches ac, abc
d D Match decimal digit or non-digit (D) dd matches 01, 55
w W Match any word character or non-char w equals [a-zA-Z0-9_]
s S Match whitespace or non-whitespace d*sd+ matches 246 98
[ ] Match any character in set [aeiou]n matches in, on
[^ ] Match any character not in set [^aeiou] matches r or 2
a | b Either a or b jpg|jpeg|gif matches .jpg
n r t New line, carriage return, tab
Method Description
Substring mystring.Substring(ndx, len)
string alpha = “abcdef”;
// returns “cdef”
string s= alpha.Substring(2);
// returns “de”
s = alpha.Substring(3,2);
ToCharArray Places selected characters in a string
in a char array:
String vowel = “aeiou”;
// create array of 5 vowels
char[] c = vowel.ToCharArray();
// create array of ‘i’ and ‘o’.
char[] c = vowel.ToCharArray(2,2);
4. System.Text.StringBuilder
Constructor
StringBuilder sb = new StringBuilder();
StringBuilder sb = new StringBuilder(mystring);
StringBuilder sb = new StringBuilder(mystring,capacity);
mystring – Initial value of StringBuilder object
capacity – Initial size (characters) of buffer.
Using StringBuilderMembers
decimal bmi = 22.2M;
int wt=168;
StringBuilder sb = new StringBuilder(“My weight is ”);
sb = sb.Append(wt); // can append number
sb= sb.Append(“ and my bmi is ”).Append(bmi);
// my weight is 168 and my bmi is 22.2
sb= sb.Replace(“22.2”,”22.4”);
string s = sb.ToString();
// Clear and set to new value
sb.Length=0;
sb.Append(“Xanadu”);
5. DateTime and TimeSpan
DateTime Constructor
DateTime(yr, mo, day)
DateTime(yr, mo, day, hr, min, sec)
DateTime bday = new DateTime(1964,12,20,11,2,0);
DateTime newyr= DateTime.Parse(“1/1/2005”);
DateTime currdt = DateTime.Now;
// also AddHours, AddMonths, AddYears
DateTime tomorrow = currdt.AddDays(1);
TimeSpan diff = currdt.Subtract(bday);
// 14795 days from 12/20/64 to 6/24/05
Console.WriteLine(“{0}”, diff.Days);
// TimeSpan(hrs, min, sec)
TimeSpan ts = new TimeSpan(6, 30, 10);
// also FromMinutes, FromHours, FromDays
TimeSpan ts = TimeSpan.FromSeconds(120);
TimeSpan ts = ts2 – ts1; // +,-,>,<,==, !=

8. Using the C# Compiler at the Command Line
C:>csc /t:library /out:reslib.dll mysource.cs
csc /t:winexe /r:ctls1.dll /r:ctls2.dll winapp.cs
csc /keyfile:strongkey.snk secure.cs
Option Description
/addmodule Import metadata from a file that does
not contain a manifest.
/debug Tells compiler to emit debugging info.
/doc Specifies an XML documentation file
to be created during compilation.
/keyfile Specifies file containing key used to
create a strong named assembly.
/lib Specifies directory to search for
external referenced assemblies.
/out Name of compiled output file.
/reference (/r) Reference to an external assembly.
/resource Resource file to embed in output.
/target (/t) /t:exe /t:library /t:module /t:winexe
9. C# Language Fundamentals
Control Flow Statements
switch (expression)
{ case expression:
// statements
break / goto / return()
case ...
default:
// statements
break / goto / return()
}
expression may be
integer, string, or enum.
switch (genre)
{
case “vhs”:
price= 10.00M;
break;
case “dvd”:
price=16.00M;
break;
default:
price=12.00M:
break;
}
if (condition) {
// statements
} else {
// statements
}
if (genre==”vhs”)
price=10.00M;
else if (genre==”dvd”)
price=16.00M;
else price=12.00M;
Loop Constructs
while (condition)
{ body }
do { body }
while (condition);
while ( ct < 8)
{ tot += ct; ct++; }
do { tot += ct; ct++;}
while (ct < 8);
11. Delegates and Events
Delegates
[modifiers] delegate result-type delegate name ([parameter list]);
// (1) Define a delegate that calls method(s) having a single string parameter
public delegate void StringPrinter(string s);
// (2) Register methods to be called by delegate
StringPrinter prt = new StringPrinter(PrintLower);
prt += new StringPrinter(PrintUpper);
prt(“Copyright was obtained in 2005”); / / execute PrintLower and PrintUpper
Using Anonymous Methods with a Delegate
Rather than calling a method, a delegate encapsulates code that is executed:
prt = delegate(string s) { Console.WriteLine(s.ToLower()); };
prt += delegate(string s) { Console.WriteLine(s.ToUpper()); };
prt(“Print this in lower and upper case.”);
Events
// class.event += new delegate(event handler method);
Button Total = new Button();
Total.Click += new EventHandler(GetTotal);
// Event Handler method must have signature specified by delegate
private void GetTotal( object sender, EventArgs e) {
Commonly used Control Events
Event Delegate
Click, MouseEnter
DoubleClick, MouseLeave
EventHandler( object sender, EventArgs e)
MouseDown, Mouseup,
MouseMove
MouseEventHandler(object sender,
MouseEventArgs e)
e.X, e.Y – x and y coordinates
e.Button – MouseButton.Left, Middle, Right
KeyUp, KeyDown KeyEventHandler(object sndr, KeyEventArgs e)
e.Handled – Indicates whether event is handled.
e.KeyCode – Keys enumeration, e.g., Keys.V
e.Modifiers – Indicates if Alt, Ctrl, or Shift key.
KeyPress KeyPressEventHandler(object sender,
KeyPressEventArgs e)
12. struct
[attribute][modifier] struct name [:interfaces] { struct-body}
Differences from class:
• is a value type • cannot inherit from a class or be inherited
• fields cannot have initializer • explicit constructor must have a parameter
13. enum (Enumerated Type)
enum enum Operations
enum Fabric: int {
cotton = 1,
silk = 2,
wool = 4,
rayon = 8
}
int cotNum = (int) Fabric.cotton; // 1
string cotName = Fabric.cotton.ToString(); // cotton
string s = Enum.GetName(typeof(Fabric),2); // silk
// Create instance of wool enum if it is valid
if(Enum.IsDefined(typeof(Fabric), “wool”) Fabric woolFab
= (Fabric)Enum.Parse(typeof(Fabric),”wool”);
Loop Constructs (Continued)
for (initializer;
termination condition;
iteration;)
{ // statements }
foreach (type identifier in
collection)
{ // statements }
for (int i=0;i<8;i++)
{
tot += i;
}
int[] ages = {27, 33, 44};
foreach(int age in ages)
{ tot += age; }
10. C# Class Definition
Class
[public | protected | internal | private]
[abstract | sealed | static]
class class name [:class/interfaces inherited from]
Constructor
[access modifier] class name (parameters) [:initializer]
initializer – base calls constructor in base class.
this calls constructor within class.
public class Shirt: Apparel {
public Shirt(decimal p, string v) : base(p,v)
{ constructor body }
Method
[access modifier]
[static | virtual | override | new | sealed | abstract ]
method name (parameter list) { body }
virtual – method can be overridden in subclass.
override – overrides virtual method in base class.
new – hides non-virtual method in base class.
sealed – prevents derived class from inheriting.
abstract – must be implemented by subclass.
Passing Parameters:
a. By default, parameters are passed by value.
b. Passing by reference: ref and out modifiers
string id= “gm”; // caller initializes ref
int weight; // called method initializes
GetFactor(ref id, out weight);
// ... other code here
static void GetFactor(ref string id, out int wt)
{
if (id==”gm”) wt = 454; else wt=1;
return;
}
Property
[modifier] <datatype> property name {
public string VendorName
{
get { return vendorName; }
set { vendorName = value; } // note value keyword
}

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