Cstring knowledge point in. net

1. Calculate the length of two bytes (such as Chinese characters)

For example: String STR = '"I love China ";

If Str. length is used directly, the result 9 is found, where "China". Length = 2, which is a bit unconventional. It is especially troublesome to control the string output format.

 

Code
Private   String Getformatedstring ( String P_str, Int P_len)
{
// Method 1: calculate the number of Chinese Characters
// Int ihanzilen = encoding. Default. getbytecount (p_str)-p_str.length;
// Method 2: calculate the number of Chinese Characters
Int Ihanzilen = RegEx. Matches (p_str, @" [\ U4e00-\ u9fa5] " ). Count;
Ilen = P_len - Ilen;
String Sformat =   " {0 ,- "   + Ilen. tostring () +   " } " ;
Return   String . Format (sformat, p_str );
}

 

2. halfwidth and fullwidth Conversion

Code
Public   Static   String Charconverter ( String Source)
{
System. Text. stringbuilder result =   New System. Text. stringbuilder (source. length, source. Length );
For ( Int I =   0 ; I < Source. length; I ++ )
{
If (Source [I] > =   65281   && Source [I] <=   65373 )
{
Result. append (( Char ) (Source [I] -   65248 ));
}
Else   If (Source [I] =   12288 )
{
Result. append ( '   ' );
}
Else
{
Result. append (source [I]);
}
}

ReturnResult. tostring ();
}

 

3. Calculate the pixel information of a string in a specified font.

The calculation results are slightly different using the two methods.
Method 1:
First, reference graphic object G, as shown below:

Code
G. measurestring (STR,NewFont (fontfamily, fontsize, graphicsunit. pixel ));

Create a graphics object
Receives a reference to a graphic object in a form or control paint event as part of painteventargs. Create and draw a widgetCodeThis method is usually used to obtain references to graphic objects.
Call the creategraphics method of a control or form to obtain a reference to the graphics object. This object indicates the drawing of the control or form. Use this method to draw an existing form or control.
Create a graphics object from any object inherited from the image. This method is useful when you need to change an existing image.
Method 2:

Code
Textrenderer. measuretext (STR,NewFont (fontfamily, fontsize, graphicsunit. pixel ));

The system. Windows. Forms namespace must be referenced above.

 

4. Obtain the numbers in the string.

Code
Public   Decimal Getnumber ( String Str)
{
Decimal Result =   0 ;
If (Str ! =   Null   && Str ! =   String . Empty)
{
// Regular Expressions remove non-numeric characters (excluding decimal points .)
Str = RegEx. Replace (STR, @" [^ \ D. \ D] " , "" );

//If it is a number, convert it to decimal type
If(RegEx. ismatch (STR,@"^ [+-]? \ D * [.]? \ D * $"))
{
Result= Decimal. Parse (STR );
}
}

ReturnResult;
}

 

4. Rounding of the Double Type

We often encounter rounding issues. The following two methods are provided:

1. Use the round Method

Using system. Math;
......
Round (3.045, 2) // return value: 3.05
Round (3.044, 2) // return value: 3.04

Ii. String formatting

Double Pi = 3.1415936;
......
String strpi = pi. tostring ("F3"); // return value: 3.142