C # Compare string and string common functions

C # Comparing string and string Common functions Example August 26, 2007 Sunday 02:29 There are several ways to compare strings in C #, such as:

1. String.Compare (x, y);
2. String. Equals (x, y);

If the comparison is not case-sensitive, the corresponding is:
String.Compare (x, y);
String. Equals (x, y);

Note: String.Compare The meaning of the comparison result:

Value
Meaning

Less than 0
X is less than Y. or x is a null reference (Nothing in Visual Basic).

Zero
x equals Y.

Greater than 0
X is greater than Y. Or y is a null reference (Nothing in Visual Basic).

String. The meaning of the equals comparison result is:
Value
Meaning

True
x equals Y.

False
x does not equal Y.

--------------------------------------------------------------------------------

Other commonly used string operations:

1. Extracting substrings from a string
The StringBuilder class does not have a method to support substrings, so it must be extracted with the string class.
String mystring= "My name is Ynn.";
Displays "name is Ynn."
Console.WriteLine (mystring. Substring (3));
Displays "Ynn"
Console.WriteLine (mystring. Substring (11,3));

2. Comparing strings
There are four methods of the String class: Compare (), CompareTo (), compareordinal (), Equals ().
The Compare () method is a static version of the CompareTo () method. As long as the "=" operator is used, the Equals () method is called, and the Equals () method is equivalent to "=". The CompareOrdinal () method compares two strings to the local language and file.
Example:
int result;
BOOL Bresult;
S1= "AAAA";
S2= "BBBB";
Compare () method
The result value is "0", etc., less than 0 means S1 < S2, greater than 0 means S1 > s2
Result=string.compare (S1,S2);
Result=s1.compareto (S2);
Result=string.compareordinal (S1,S2);
Bresult=s1. Equals (S2);
Bresult=string.equals (S1,S2);
One exception is that two strings are built-in and equal, and the static method is much faster.

3. String formatting

3.1 Formatting numbers
Format character descriptions and associated properties

--------------------------------------------------------------------------------

c, C currency format.
D, d decimal format.
E, E scientific count (exponential) format.
F, f fixed point format.
G, g regular format.
N, n number format.
R, R round-trip format, which ensures that a number converted to a string has the same value as the original number when it is converted back to a number.
x, x hexadecimal format.

--------------------------------------------------------------------------------

Double Val=math.pi;
Console.WriteLine (Val.    ToString ()); Displays 3.14159265358979
Console.WriteLine (Val. ToString ("E"));//displays 3.141593E+000
Console.WriteLine (Val. ToString ("F3");//displays 3.142
int val=65535;
Console.WriteLine (Val.    ToString ("x")); Displays FFFF
Console.WriteLine (Val.    ToString ("X")); Displays FFFF
Single val=0.123f;
Console.WriteLine (Val.    ToString ("P")); Displays 12.30%
Console.WriteLine (Val.    ToString ("P1")); Displays 12.3%
The default formatting puts a space between the numbers and the percent signs. The customization method is as follows:
Where the NumberFormatInfo class is a member of the System.Globalization namespace, the namespace must be imported into the program.
Single val=0.123f;
Object Myobj=numberformatinfo.currentinfo.clone () as NumberFormatInfo;
NumberFormatInfo Myformat=myobj as NumberFormatInfo;
MyFormat. Percentpositivepattern=1;
Console.WriteLine (Val. ToString ("P", MyFormat)); Displays 12.3%;
Console.WriteLine (Val. ToString ("P1", MyFormat)); Displays 12.3%;
Formatting has a lot of flexibility. The following example shows a meaningless currency structure:
Double val=1234567.89;
int [] groupsize={2,1,3};
Object Myobj=numberformatinfo.currentinfo.clone ();
NumberFormatInfo Mycurrency=myobj as NumberFormatInfo;
Mycurrency. Currencysymbol= "#"; Symbol
Mycurrency. Currencydecimalseparator= ":"; Decimal point
Mycurrency.    Currencygroupseparator= "_"; Separator
Mycurrency. Currencygroupsizes=groupsize;
Output #1_234_5_67:89
Console.WriteLine (Val. ToString ("C", mycurrency));

3.2 Formatting Dates
The output form depends on the culture settings of the user's computer.
Using System;
Using System.Globalization;
public class MainClass
{
public static void Main (string[] args)
{
DateTime dt = DateTime.Now;
string[] format = {"D", "D", "F", "F", "G", "G", "M", "R", "s", "T", "T", "U", "U", "Y", "dddd, MMMM dd yyyy", "ddd, MMM d \" \ "yy", "D DDD, MMMM dd "," M/yy "," Dd-mm-yy ",};
String date;
for (int i = 0; i < format. Length; i++)
{
date = dt. ToString (Format[i], datetimeformatinfo.invariantinfo);
Console.WriteLine (String.Concat (Format[i], ":", date));
}
}
}
d:07/11/2004 <======= Output
D:sunday, July 2004
F:sunday, July 2004 10:52
F:sunday, July 2004 10:52:36
g:07/11/2004 10:52
g:07/11/2004 10:52:36
M:july 11
R:sun, Jul 2004 10:52:36 GMT
S:2004-07-11t10:52:36
t:10:52
T:10:52:36
U:2004-07-11 10:52:36z
U:sunday, July 2004 02:52:36
y:2004 July
dddd, MMMM DD Yyyy:sunday, July 11 2004
DDD, MMM D "'" Yy:sun, Jul 11 ' 04
dddd, MMMM dd:sunday, July 11
m/yy:7/04
dd-mm-yy:11-07-04

3.3 Formatting enumerations
Enum Classmen
{
Ynn=1,
yly=2,
Css=3,
C++=4
}
Get the enumeration string information as follows:
Classmen myclassmen=classmen.yly;
Console.WriteLine (Myclassmen.     ToString ()); Displays yly
Console.WriteLine (Myclassmen. ToString ("D")); Displays 2
To get the text from the system enumeration, the person information is as follows:
DayOfWeek Day=dayofweek.friday;
Displays "Day is Friday"
Console.WriteLine (String.Format ("Day was {0:g}", day));
The formatted string "G" displays the enumeration as a string.

C # Compare string and string common functions