讲述c#中的类型转换

C# ³öÀ´Ò²ÓÐЩÈÕ×ÓÁË£¬×î½üÓÉÓÚ±à³ÌµÄÐèÒª£¬¶Ô C# µÄÀàÐÍת»»×öÁËһЩÑо¿£¬ÆäÄÚÈÝÉæ¼° C# µÄ×°Ïä/²ðÏä/±ðÃû¡¢ÊýÖµÀàÐͼäÏ໥ת»»¡¢×Ö·ûµÄ ASCII ÂëºÍ Unicode Âë¡¢ÊýÖµ×Ö·û´®ºÍÊýÖµÖ®¼äµÄת»»¡¢×Ö·û´®ºÍ×Ö·ûÊý×é/×Ö½ÚÊý×éÖ®¼äµÄת»»¡¢¸÷ÖÖÊýÖµÀàÐͺÍ×Ö½ÚÊý×éÖ®¼äµÄת»»¡¢Ê®Áù½øÖÆÊýÊä³öÒÔ¼°ÈÕÆÚÐÍÊý¾ÝµÄһЩת»»´¦Àí£¬ÔÚÕâÀïÓë´ó¼Ò·ÖÏí¨D¨D

1. ×°Ïä¡¢²ðÏ仹ÊDZðÃû

¡¡¡¡Ðí¶à C#.NET µÄÊéÉ϶¼ÓнéÉÜ int -> Int32 ÊÇÒ»¸ö×°ÏäµÄ¹ý³Ì£¬·´Ö®ÔòÊDzðÏäµÄ¹ý³Ì¡£Ðí¶àÆäËü±äÁ¿ÀàÐÍÒ²ÊÇÈç´Ë£¬È磺short <-> Int16£¬long <-> Int64 µÈ¡£¶ÔÓÚÒ»°ãµÄ³ÌÐòÔ±À´Ëµ£¬´ó¿É²»±ØÈ¥Á˽âÕâÒ»¹ý³Ì£¬ÒòΪÕâЩװÏäºÍ²ðÏäµÄ¶¯×÷¶¼ÊÇ¿ÉÒÔ×Ô¶¯Íê³ÉµÄ£¬²»ÐèҪд´úÂë½øÐиÉÔ¤¡£µ«ÊÇÎÒÃÇÐèÒª¼ÇסÕâЩÀàÐÍÖ®¼äµÄ¹Øϵ£¬ËùÒÔ£¬ÎÒÃÇʹÓá°±ðÃû¡±À´¼ÇÒäËüÃÇÖ®¼äµÄ¹Øϵ¡£
C# ÊÇÈ«ÃæÏò¶ÔÏóµÄÓïÑÔ£¬±È Java µÄÃæÏò¶ÔÏ󶼻¹³¹µ×¨D¨DËü°Ñ¼òµ¥Êý¾ÝÀàÐÍͨ¹ýĬÈϵÄ×°Ï䶯×÷·â×°³ÉÁËÀà¡£Int32¡¢Int16¡¢Int64 µÈ¾ÍÊÇÏàÓ¦µÄÀàÃû£¬¶øÄÇЩÎÒÃÇÊìϤµÄ¡¢¼òµ¥Ò׼ǵÄÃû³Æ£¬Èç int¡¢short¡¢long µÈ£¬ÎÒÃǾͿÉÒÔ°ÑËü³Æ×÷ÊÇ Int32¡¢Int16¡¢Int64 µÈÀàÐ͵ıðÃû¡£
¡¡¡¡ÄÇô³ýÁËÕâÈýÖÖÀàÐÍÖ®Í⣬»¹ÓÐÄÄЩÀàÓС°±ðÃû¡±ÄØ£¿³£ÓõÄÓÐÈçÏÂһЩ£º

bool -> System.Boolean (²¼¶ûÐÍ£¬ÆäֵΪ true »òÕß false)
char -> System.Char (×Ö·ûÐÍ£¬Õ¼ÓÐÁ½¸ö×Ö½Ú£¬±íʾ 1 ¸ö Unicode ×Ö·û)
byte -> System.Byte (×Ö½ÚÐÍ£¬Õ¼ 1 ×Ö½Ú£¬±íʾ 8 λÕýÕûÊý£¬·¶Î§ 0 ~ 255)
sbyte -> System.SByte (´ø·ûºÅ×Ö½ÚÐÍ£¬Õ¼ 1 ×Ö½Ú£¬±íʾ 8 λÕûÊý£¬·¶Î§ -128 ~ 127)
ushort -> System.UInt16 (ÎÞ·ûºÅ¶ÌÕûÐÍ£¬Õ¼ 2 ×Ö½Ú£¬±íʾ 16 λÕýÕûÊý£¬·¶Î§ 0 ~ 65,535)
uint -> System.UInt32 (ÎÞ·ûºÅÕûÐÍ£¬Õ¼ 4 ×Ö½Ú£¬±íʾ 32 λÕýÕûÊý£¬·¶Î§ 0 ~ 4,294,967,295)
ulong -> System.UInt64 (ÎÞ·ûºÅ³¤ÕûÐÍ£¬Õ¼ 8 ×Ö½Ú£¬±íʾ 64 λÕýÕûÊý£¬·¶Î§ 0 ~ ´óÔ¼ 10 µÄ 20 ´Î·½)
short -> System.Int16 (¶ÌÕûÐÍ£¬Õ¼ 2 ×Ö½Ú£¬±íʾ 16 λÕûÊý£¬·¶Î§ -32,768 ~ 32,767)
int -> System.Int32 (ÕûÐÍ£¬Õ¼ 4 ×Ö½Ú£¬±íʾ 32 λÕûÊý£¬·¶Î§ -2,147,483,648 µ½ 2,147,483,647)
long -> System.Int64 (³¤ÕûÐÍ£¬Õ¼ 8 ×Ö½Ú£¬±íʾ 64 λÕûÊý£¬·¶Î§´óÔ¼ -(10 µÄ 19) ´Î·½ µ½ 10 µÄ 19 ´Î·½)
float -> System.Single (µ¥¾«¶È¸¡µãÐÍ£¬Õ¼ 4 ¸ö×Ö½Ú)
double -> System.Double (Ë«¾«¶È¸¡µãÐÍ£¬Õ¼ 8 ¸ö×Ö½Ú)

¡¡¡¡ÎÒÃÇ¿ÉÒÔÓÃÏÂÁдúÂë×öÒ»¸öʵÑ飺

private void TestAlias() {
// this.textBox1 ÊÇÒ»¸öÎı¾¿ò£¬ÀàÐÍΪ System.Windows.Forms.TextBox
// Éè¼ÆÖÐÒѾ­½«Æä Multiline ÊôÐÔÉèÖÃΪ true
byte a = 1; char b = 'a'; short c = 1;
int d = 2; long e = 3; uint f = 4; bool g = true;
this.textBox1.Text = "";
this.textBox1.AppendText("byte -> " + a.GetType().FullName + "\n");
this.textBox1.AppendText("char -> " + b.GetType().FullName + "\n");
this.textBox1.AppendText("short -> " + c.GetType().FullName + "\n");
this.textBox1.AppendText("int -> " + d.GetType().FullName + "\n");
this.textBox1.AppendText("long -> " + e.GetType().FullName + "\n");
this.textBox1.AppendText("uint -> " + f.GetType().FullName + "\n");
this.textBox1.AppendText("bool -> " + g.GetType().FullName + "\n");
}
¡¡¡¡ÔÚ´°ÌåÖÐн¨Ò»¸ö°´Å¥£¬²¢ÔÚËüµÄµ¥»÷ʼþÖе÷Óøà TestAlias() º¯Êý£¬ÎÒÃǽ«¿´µ½ÔËÐнá¹ûÈçÏ£º

byte -> System.Byte
char -> System.Char
short -> System.Int16
int -> System.Int32
long -> System.Int64
uint -> System.UInt32
bool -> System.Boolean

¡¡¡¡Õâ×ãÒÔ˵Ã÷¸÷±ðÃû¶ÔÓ¦µÄÀ࣡

2. ÊýÖµÀàÐÍÖ®¼äµÄÏ໥ת»»

¡¡¡¡ÕâÀïËù˵µÄÊýÖµÀàÐÍ°üÀ¨ byte, short, int, long, fload, double µÈ£¬¸ù¾ÝÕâ¸öÅÅÁÐ˳Ðò£¬¸÷ÖÖÀàÐ͵ÄÖµÒÀ´Î¿ÉÒÔÏòºó×Ô¶¯½øÐÐת»»¡£¾Ù¸öÀýÀ´Ëµ£¬°ÑÒ»¸ö short Ð͵ÄÊý¾Ý¸³Öµ¸øÒ»¸ö int Ð͵ıäÁ¿£¬short Öµ»á×Ô¶¯ÐÐת»»³É int ÐÍÖµ£¬ÔÙ¸³¸ø int ÐͱäÁ¿¡£ÈçÏÂÀý£º

private void TestBasic() {
byte a = 1; short b = a; int c = b;
long d = c; float e = d; double f = e;
this.textBox1.Text = "";
this.textBox1.AppendText("byte a = " + a.ToString() + "\n");
this.textBox1.AppendText("short b = " + b.ToString() + "\n");
this.textBox1.AppendText("int c = " + c.ToString() + "\n");
this.textBox1.AppendText("long d = " + d.ToString() + "\n");
this.textBox1.AppendText("float e = " + e.ToString() + "\n");
this.textBox1.AppendText("double f = " + f.ToString() + "\n");
}
¡¡¡¡Òë˳Àûͨ¹ý£¬ÔËÐнá¹ûÊǸ÷±äÁ¿µÄÖµ¾ùΪ 1£»µ±È»£¬ËüÃǵÄÀàÐÍ·Ö±ð»¹ÊÇ System.Byte ÐÍ¡­¡­System.Double ÐÍ¡£ÏÖÔÚÎÒÃÇÀ´ÊÔÊÔ£¬Èç¹û°Ñ¸³ÖµµÄ˳Ðò·´¹ýÀ´»áÔõôÑùÄØ£¿ÔÚ TestBasic() º¯ÊýÖÐ×·¼ÓÈçÏÂÓï¾ä£º

int g = 1;
short h = g;
this.textBox1.AppendText("h = " + h.ToString() + "\n");

¡¡¡¡½á¹û±àÒ뱨´í£º
¡¡¡¡G:\Projects\Visual C#\Convert\Form1.cs(118): ÎÞ·¨½«ÀàÐÍ¡°int¡±Òþʽת»»Îª¡°short¡±
¡¡¡¡ÆäÖУ¬Form1.cs µÄ 118 Ðм´ short h = g ËùÔÚÐС£

¡¡¡¡Õâ¸öʱºò£¬Èç¹ûÎÒÃǼá³ÖÒª½øÐÐת»»£¬¾ÍÓ¦¸ÃʹÓÃÇ¿ÖÆÀàÐÍת»»£¬ÕâÔÚ C ÓïÑÔÖг£ÓÐÌá¼°£¬¾ÍÊÇʹÓá°(ÀàÐÍÃû) ±äÁ¿Ãû¡±ÐÎʽµÄÓï¾äÀ´¶ÔÊý¾Ý½øÐÐÇ¿ÖÆת»»¡£ÈçÉÏÀýÐÞ¸ÄÈçÏ£º

short g = 1;
byte h = (byte) g; // ½« short Ð굀 g µÄֵǿÖÆת»»³É short ÐͺóÔÙ¸³¸ø±äÁ¿ h
this.textBox1.AppendText("h = " + h.ToString() + "\n");

¡¡¡¡±àÒëͨ¹ý£¬ÔËÐнá¹ûÊä³öÁË h = 1£¬×ª»»³É¹¦¡£
¡¡¡¡µ«ÊÇ£¬Èç¹ûÎÒÃÇʹÓÃÇ¿ÖÆת»»£¬¾Í²»µÃ²»ÔÙ¿¼ÂÇÒ»¸öÎÊÌ⣺short Ð͵ķ¶Î§ÊÇ -32768 ~ 23767£¬¶ø byte Ð͵ķ¶Î§ÊÇ 0 ~ 255£¬ÄÇô£¬Èç¹û±äÁ¿ g µÄ´óС³¬¹ýÁË byte Ð͵ķ¶Î§ÓÖ»á³öÏÖʲôÑùµÄÇé¿öÄØ£¿ÎÒÃDz»·ÁÔÙÒ»´Î¸Äд´úÂ룬½«Öµ¸ÄΪ 265£¬±È 255 ´ó 10

short g = 265; //265 = 255 + 10
byte h = (byte) g;
this.textBox1.AppendText("h = " + h.ToString() + "\n");

¡¡¡¡±àÒëûÓгö´í£¬ÔËÐнá¹ûÈ´²»ÊÇ h = 265£¬¶øÊÇ h = 9¡£
Òò´Ë£¬ÎÒÃÇÔÚ½øÐÐת»»µÄʱºò£¬Ó¦µ±×¢Òⱻת»»µÄÊý¾Ý²»Äܳ¬³öÄ¿±êÀàÐ͵ķ¶Î§¡£Õâ²»½öÌåÏÖÔÚ¶à×Ö½ÚÊý¾ÝÀàÐÍ(Ïà¶Ô£¬ÈçÉÏÀýµÄ short) ת»»ÎªÉÙ×Ö½ÚÀàÐÍ(Ïà¶Ô£¬ÈçÉÏÀýµÄ byte) ʱ£¬Ò²ÌåÏÖÔÚ×Ö½ÚÊýÏàͬµÄÓзûºÅÀàÐͺÍÎÞ·ûºÅÀàÐÍÖ®¼ä£¬È罫 byte µÄ 129 ת»»Îª sbyte ¾Í»áÒç³ö¡£Õâ·½ÃæµÄÀý×Ó´óͬСÒ죬¾Í²»Ïêϸ˵Ã÷ÁË¡£

3. ×Ö·ûµÄ ASCII ÂëºÍ Unicode Âë

¡¡¡¡ºÜ¶àʱºòÎÒÃÇÐèÒªµÃµ½Ò»¸öÓ¢ÎÄ×Ö·ûµÄ ASCII Â룬»òÕßÒ»¸öºº×Ö×Ö·ûµÄ Unicode Â룬»òÕß´ÓÏà¹ØµÄ±àÂë²éѯËüÊÇÄÄÒ»¸ö×Ö·ûµÄ±àÂë¡£ºÜ¶àÈË£¬ÓÈÆäÊÇ´Ó VB ³ÌÐòÐòת¹ýÀ´Ñ§ C# µÄÈË£¬»á±¨Ô¹ C# ÀïΪʲôûÓÐÌṩÏֳɵĺ¯ÊýÀ´×öÕâ¸öÊÂÇé¨D¨DÒòΪÔÚ VB ÖÐÓÐ Asc() º¯ÊýºÍ Chr() º¯ÊýÓÃÓÚÕâÀàת»»¡£
µ«ÊÇÈç¹ûÄãѧ¹ý C£¬Äã¾Í»áÇå³þ£¬ÎÒÃÇÖ»ÐèÒª½«Ó¢ÎÄ×Ö·ûÐÍÊý¾ÝÇ¿ÖÆת»»³ÉºÏÊʵÄÊýÖµÐÍÊý¾Ý£¬¾Í¿ÉÒԵõ½ÏàÓ¦µÄ ASCII Â룻·´Ö®£¬Èç¹û½«Ò»¸öºÏÊʵÄÊýÖµÐÍÊý¾ÝÇ¿ÖÆת»»³É×Ö·ûÐÍÊý¾Ý£¬¾Í¿ÉÒԵõ½ÏàÓ¦µÄ×Ö·û¡£
C# ÖÐ×Ö·ûµÄ·¶Î§À©´óÁË£¬²»½ö°üº¬Á˵¥×Ö½Ú×Ö·û£¬Ò²¿ÉÒÔ°üº¬Ë«×Ö½Ú×Ö·û£¬ÈçÖÐÎÄ×Ö·ûµÈ¡£¶øÔÚ×Ö·ûºÍ±àÂëÖ®¼äµÄת»»£¬ÔòÈÔÑÓÓÃÁË C ÓïÑÔµÄ×ö·¨¨D¨DÇ¿ÖÆת»»¡£²»·Á¿´¿´ÏÂÃæµÄÀý×Ó

private void TestChar() {
char ch = 'a'; short ii = 65;
this.textBox1.Text = "";
this.textBox1.AppendText("The ASCII code of \'" + ch + "\' is: " + (short) ch + "\n");
this.textBox1.AppendText("ASCII is " + ii.ToString() + ", the char is: " + (char) ii + "\n");
char cn = 'ÖÐ'; short uc = 22478;
this.textBox1.AppendText("The Unicode of \'" + cn + "\' is: " + (short) cn + "\n");
this.textBox1.AppendText("Unicode is " + uc.ToString() + ", the char is: " + (char) uc + "\n");
}
¡¡¡¡ËüµÄÔËÐнá¹ûÊÇ

The ASCII code of 'a' is: 97
ASCII is 65, the char is: A
The Unicode of 'ÖÐ' is: 20013
Unicode is 22478, the char is: ³Ç

¡¡¡¡´ÓÕâ¸öÀý×ÓÖУ¬ÎÒÃDZãÄܷdz£Çå³þµÄÁ˽â¨D¨Dͨ¹ýÇ¿ÖÆת»»£¬¿ÉÒÔµÃÒÔ×Ö·ûµÄ±àÂ룬»òÕߵõ½±àÂë±íʾµÄ×Ö·û¡£Èç¹ûÄãÐèÒªµÄ²»ÊÇ short Ð͵ıàÂ룬Çë²Î¿¼µÚ 1 Ìõ½øÐÐת»»£¬¼´¿ÉµÃµ½ int µÈÀàÐ͵ıàÂëÖµ¡£

4. ÊýÖµ×Ö·û´®ºÍÊýÖµÖ®¼äµÄת»»

¡¡¡¡Ê×ÏÈ£¬ÎÒÃǵøãÃ÷°×£¬Ê²Ã´ÊÇÊýÖµ×Ö·û´®¡£ÎÒÃÇÖªµÀ£¬ÔÚ C# ÖУ¬×Ö·û´®ÊÇÓÃÒ»¶ÔË«ÒýºÅ°üº¬µÄÈô¸É×Ö·ûÀ´±íʾµÄ£¬Èç "123"¡£¶ø "123" ÓÖÏà¶ÔÌØÊ⣬ÒòΪ×é³É¸Ã×Ö·û´®µÄ×Ö·û¶¼ÊÇÊý×Ö£¬ÕâÑùµÄ×Ö·û´®£¬¾ÍÊÇÊýÖµ×Ö·û´®¡£ÔÚÎÒÃǵÄÑÛÖУ¬Õâ¼´ÊÇÒ»´®×Ö·û£¬Ò²ÊÇÒ»¸öÊý£¬µ«¼ÆËã»úÈ´Ö»ÈÏΪËüÊÇÒ»¸ö×Ö·û´®£¬²»ÊÇÊý¡£Òò´Ë£¬ÎÒÃÇÔÚijЩʱºò£¬±ÈÈçÊäÈëÊýÖµµÄʱºò£¬°Ñ×Ö·û´®×ª»»³ÉÊýÖµ£»¶øÔÚÁíһЩʱºò£¬ÎÒÃÇÐèÒªÏà·´µÄת»»¡£
¡¡¡¡½«Êýֵת»»³É×Ö·û´®·Ç³£¼òµ¥£¬ÒòΪÿһ¸öÀ඼ÓÐÒ»¸ö void ToString() ·½·¨¡£ËùÓÐÊýÖµÐ굀 void ToString() ·½·¨¶¼Äܽ«Êý¾Ýת»»ÎªÊýÖµ×Ö·û´®¡£Èç 123.ToSting() ¾Í½«µÃµ½×Ö·û´® "123"¡£
ÄÇô·´¹ýÀ´£¬½«ÊýÖµÐÍ×Ö·û´®×ª»»³ÉÊýÖµÓÖ¸ÃÔõô°ìÄØ£¿ÎÒÃÇ×Ðϸ²éÕÒһϣ¬»á·¢ÏÖ short, int, float µÈÊýÖµÀàÐ;ùÓÐÒ»¸ö static Parse() º¯Êý¡£Õâ¸öº¯Êý¾ÍÊÇÓÃÀ´½«×Ö·û´®×ª»»ÎªÏàÓ¦ÊýÖµµÄ¡£ÎÒÃÇÒÔÒ»¸ö float ÀàÐ͵Äת»»ÎªÀý£º float f = float.Parse("543.21"); Æä½á¹û f µÄֵΪ 543.21F¡£µ±È»£¬ÆäËüµÄÊýÖµÀàÐÍÒ²¿ÉÒÔʹÓÃͬÑùµÄ·½·¨½øÐÐת»»£¬ÏÂÃæµÄÀý×Ó¿ÉÒÔ¸üÃ÷È·µÄ˵Ã÷ת»»µÄ·½·¨£º

private void TestStringValue() {
float f = 54.321F;
string str = "123";
this.textBox1.Text = "";
this.textBox1.AppendText("f = " + f.ToString() + "\n");
if (int.Parse(str) == 123) {
this.textBox1.AppendText("str convert to int successfully.");
} else {
this.textBox1.AppendText("str convert to int failed.");
}
}
¡¡¡¡ÔËÐнá¹û£º

f = 54.321
str convert to int successfully.

5. ×Ö·û´®ºÍ×Ö·ûÊý×éÖ®¼äµÄת»»

¡¡¡¡×Ö·û´®Àà System.String ÌṩÁËÒ»¸ö void ToCharArray() ·½·¨£¬¸Ã·½·¨¿ÉÒÔʵÏÖ×Ö·û´®µ½×Ö·ûÊý×éµÄת»»¡£ÈçÏÂÀý£º

private void TestStringChars() {
string str = "mytest";
char[] chars = str.ToCharArray();
this.textBox1.Text = "";
this.textBox1.AppendText("Length of \"mytest\" is " + str.Length + "\n");
this.textBox1.AppendText("Length of char array is " + chars.Length + "\n");
this.textBox1.AppendText("char[2] = " + chars[2] + "\n");
}
¡¡¡¡ÀýÖÐÒÔ¶Ôת»»×ª»»µ½µÄ×Ö·ûÊý×鳤¶ÈºÍËüµÄÒ»¸öÔªËؽøÐÐÁ˲âÊÔ£¬½á¹ûÈçÏ£º

Length of "mytest" is 6
Length of char array is 6
char[2] = t

¡¡¡¡¿ÉÒÔ¿´³ö£¬½á¹ûÍêÈ«ÕýÈ·£¬Õâ˵Ã÷ת»»³É¹¦¡£ÄÇô·´¹ýÀ´£¬Òª°Ñ×Ö·ûÊý×éת»»³É×Ö·û´®ÓÖ¸ÃÈçºÎÄØ£¿
¡¡¡¡ÎÒÃÇ¿ÉÒÔʹÓà System.String ÀàµÄ¹¹Ô캯ÊýÀ´½â¾öÕâ¸öÎÊÌâ¡£System.String ÀàÓÐÁ½¸ö¹¹Ô캯ÊýÊÇͨ¹ý×Ö·ûÊý×éÀ´¹¹ÔìµÄ£¬¼´ String(char[]) ºÍ String[char[], int, int)¡£ºóÕßÖ®ËùÒÔ¶àÁ½¸ö²ÎÊý£¬ÊÇÒòΪ¿ÉÒÔÖ¸¶¨ÓÃ×Ö·ûÊý×éÖеÄÄÄÒ»²¿·ÖÀ´¹¹Ôì×Ö·û´®¡£¶øÇ°ÕßÔòÊÇÓÃ×Ö·ûÊý×éµÄÈ«²¿ÔªËØÀ´¹¹Ôì×Ö·û´®¡£ÎÒÃÇÒÔÇ°ÕßΪÀý£¬ÔÚ TestStringChars() º¯ÊýÖÐÊäÈëÈçÏÂÓï¾ä£º

char[] tcs = {'t', 'e', 's', 't', ' ', 'm', 'e'};
string tstr = new String(tcs);
this.textBox1.AppendText("tstr = \"" + tstr + "\"\n");

¡¡¡¡ÔËÐнá¹ûÊäÈë tstr = "test me"£¬²âÊÔ˵Ã÷ת»»³É¹¦¡£
¡¡¡¡Êµ¼ÊÉÏ£¬ÎÒÃÇÔںܶàʱºòÐèÒª°Ñ×Ö·û´®×ª»»³É×Ö·ûÊý×éÖ»ÊÇΪÁ˵õ½¸Ã×Ö·û´®ÖеÄij¸ö×Ö·û¡£Èç¹ûÖ»ÊÇΪÁËÕâ¸öÄ¿µÄ£¬ÄÇ´ó¿É²»±ØÐËʦ¶¯ÖÚµÄÈ¥½øÐÐת»»£¬ÎÒÃÇÖ»ÐèҪʹÓà System.String µÄ [] ÔËËã·û¾Í¿ÉÒԴﵽĿµÄ¡£Çë¿´ÏÂÀý£¬ÔÙÔÚ TestStringChars() º¯ÊýÖмÓÈëÈçÈçÏÂÓïÃû£º

char ch = tstr[3];
this.textBox1.AppendText("\"" + tstr + "\"[3] = " + ch.ToString());

¡¡¡¡ÕýÈ·µÄÊä³öÊÇ "test me"[3] = t£¬¾­²âÊÔ£¬Êä³öÕýÈ·¡£

6. ×Ö·û´®ºÍ×Ö½ÚÊý×éÖ®¼äµÄת»»

¡¡¡¡Èç¹û»¹Ïë´Ó System.String ÀàÖÐÕÒµ½·½·¨½øÐÐ×Ö·û´®ºÍ×Ö½ÚÊý×éÖ®¼äµÄת»»£¬¿ÖÅÂÄã»áʧÍûÁË¡£ÎªÁ˽øÐÐÕâÑùµÄת»»£¬ÎÒÃDz»µÃ²»½èÖúÁíÒ»¸öÀࣺSystem.Text.Encoding¡£¸ÃÀàÌṩÁË bye[] GetBytes(string) ·½·¨½«×Ö·û´®×ª»»³É×Ö½ÚÊý×飬»¹ÌṩÁË string GetString(byte[]) ·½·¨½«×Ö½ÚÊý×éת»»³É×Ö·û´®¡£
¡¡¡¡System.Text.Encoding ÀàËƺõûÓпÉÓõĹ¹Ô캯Êý£¬µ«ÎÒÃÇ¿ÉÒÔÕÒµ½¼¸¸öĬÈ쵀 Encoding£¬¼´ Encoding.Default(»ñȡϵͳµÄµ±Ç° ANSI ´úÂëÒ³µÄ±àÂë)¡¢Encoding.ASCII(»ñÈ¡ 7 λ ASCII ×Ö·û¼¯µÄ±àÂë)¡¢Encoding.Unicode(»ñÈ¡²ÉÓà Little-Endian ×Ö½Ú˳ÐòµÄ Unicode ¸ñʽµÄ±àÂë)¡¢Encoding.UTF7(»ñÈ¡ UTF-7 ¸ñʽµÄ±àÂë)¡¢Encoding.UTF8(»ñÈ¡ UTF-8 ¸ñʽµÄ±àÂë) µÈ¡£ÕâÀïÖ÷Ҫ˵˵ Encoding.Default ºÍ Encoding.Unicode ÓÃÓÚת»»µÄÇø±ð¡£
¡¡¡¡ÔÚ×Ö·û´®×ª»»µ½×Ö½ÚÊý×éµÄ¹ý³ÌÖУ¬Encoding.Default »á½«Ã¿¸öµ¥×Ö½Ú×Ö·û£¬Èç°ë½ÇÓ¢ÎÄ£¬×ª»»³É 1 ¸ö×Ö½Ú£¬¶ø°Ñÿ¸öË«×Ö½Ú×Ö·û£¬È纺×Ö£¬×ª»»³É 2 ¸ö×Ö½Ú¡£¶ø Encoding.Unicode Ôò»á½«ËüÃǶ¼×ª»»³ÉÁ½¸ö×Ö½Ú¡£ÎÒÃÇ¿ÉÒÔͨ¹ýÏÂÁмòµ¥µÄÁ˽âÒ»ÏÂת»»µÄ·½·¨£¬ÒÔ¼°Ê¹Óà Encoding.Default ºÍ Encodeing.Unicode µÄÇø±ð£º

private void TestStringBytes() {
string s = "C#ÓïÑÔ";
byte[] b1 = System.Text.Encoding.Default.GetBytes(s);
byte[] b2 = System.Text.Encoding.Unicode.GetBytes(s);
string t1 = "", t2 = "";
foreach (byte b in b1) {
t1 += b.ToString("") + " ";
}
foreach (byte b in b2) {
t2 += b.ToString("") + " ";
}
this.textBox1.Text = "";
this.textBox1.AppendText("b1.Length = " + b1.Length + "\n");
this.textBox1.AppendText(t1 + "\n");
this.textBox1.AppendText("b2.Length = " + b2.Length + "\n");
this.textBox1.AppendText(t2 + "\n");
}

¡¡¡¡ÔËÐнá¹ûÈçÏ£¬²»ËµÏêÊö£¬ÏàÐÅ´ó¼ÒÒѾ­Ã÷°×ÁË¡£

b1.Length = 6
67 35 211 239 209 212
b2.Length = 8
67 0 35 0 237 139 0 138

¡¡¡¡½«×Ö½ÚÊý×éת»»³É×Ö·û´®£¬Ê¹Óà Encoding ÀàµÄ string GetString(byte[]) »ò string GetString(byte[], int, int) ·½·¨£¬¾ßÌåʹÓúÎÖÖ Encoding »¹ÊÇÓɱàÂë¾ö¶¨¡£ÔÚ TestStringBytes() º¯ÊýÖÐÌí¼ÓÈçÏÂÓï¾ä×÷ΪʵÀý£º

byte[] bs = {97, 98, 99, 100, 101, 102};
string ss = System.Text.Encoding.ASCII.GetString(bs);
this.textBox1.AppendText("The string is: " + ss + "\n");

¡¡¡¡ÔËÐнá¹ûΪ£ºThe string is: abcdef

7. ¸÷ÖÖÊýÖµÀàÐͺÍ×Ö½ÚÊý×éÖ®¼äµÄת»»

¡¡¡¡ÔÚµÚ 1 ÌõÖÐÎÒÃÇ¿ÉÒԲ鵽¸÷ÖÖÊýÖµÐÍÐèҪʹÓöàÉÙ×ֽڵĿռäÀ´±£´æÊý¾Ý¡£½«Ä³ÖÖÊýÖµÀàÐ͵ÄÊý¾Ýת»»³É×Ö½ÚÊý×éµÄʱºò£¬µÃµ½µÄÒ»¶¨ÊÇÏàÓ¦´óСµÄ×Ö½ÚÊý×飻ͬÑù£¬ÐèÒª°Ñ×Ö½ÚÊý×éת»»³ÉÊýÖµÀàÐÍ£¬Ò²ÐèÒªÕâ¸ö×Ö½ÚÊý×é´óÓÚÏàÓ¦ÊýÖµÀàÐ͵Ä×Ö½ÚÊý¡£
¡¡¡¡ÏÖÔÚ½éÉÜ´ËÀàת»»µÄÖ÷½Ç£ºSystem.BitConverter¡£¸ÃÀàÌṩÁË byte[] GetBytes(...) ·½·¨½«¸÷ÖÖÊýÖµÀàÐÍת»»³É×Ö½ÚÊý×飬ҲÌṩÁË ToInt32¡¢ToInt16¡¢ToInt64¡¢ToUInt32¡¢ToSignle¡¢ToBoolean µÈ·½·¨½«×Ö½ÚÊý×éת»»³ÉÏàÓ¦µÄÊýÖµÀàÐÍ¡£

¡¡¡¡ÓÉÓÚÕâÀàת»»Í¨³£Ö»ÊÇÔÚÐèÒª½øÐнÏϸ΢µÄ±àÂë/½âÂë²Ù×÷ʱ²Å»áÓõ½£¬ËùÒÔÕâÀï¾Í²»ÏêϸÐðÊöÁË£¬½ö°Ñ System.BitConverter Àà½éÉܸø´ó¼Ò¡£

8. ת»»³ÉÊ®Áù½øÖÆ

¡¡¡¡ÈκÎÊý¾ÝÔÚ¼ÆËã»úÄÚ²¿¶¼ÊÇÒÔ¶þ½øÖƱ£´æµÄ£¬ËùÒÔ½øÖÆÓëÊý¾ÝµÄ´æ´¢Î޹أ¬Ö»ÓëÊäÈëÊä³öÓйء£ËùÒÔ£¬¶ÔÓÚ½øÖÆת»»£¬ÎÒÃÇÖ»¹ØÐÄ×Ö·û´®ÖеĽá¹û¡£
¡¡¡¡ÔÚÉÏÃæµÄµÚ 4 ÌõÖÐÌáµ½ÁË ToString() ·½·¨¿ÉÒÔ½«Êýֵת»»³É×Ö·û´®£¬²»¹ýÔÚ×Ö·û´®ÖУ¬½á¹ûÊÇÒÔÊ®½øÖÆÏÔʾµÄ¡£ÏÖÔÚÎÒÃÇ´ø¸øËü¼ÓһЩ²ÎÊý£¬¾Í¿ÉÒÔ½«Æäת»»³ÉÊ®Áù½øÖƨD¨DʹÓà ToString(string) ·½·¨¡£
¡¡¡¡ÕâÀïÐèÒªÒ»¸ö string ÀàÐ͵IJÎÊý£¬Õâ¾ÍÊǸñʽ˵Ã÷·û¡£Ê®Áù½øÖƵĸñʽ˵Ã÷·ûÊÇ "x" »òÕß "X"£¬Ê¹ÓÃÕâÁ½ÖÖ¸ñʽ˵Ã÷·ûµÄÇø±ðÖ÷ÒªÔÚÓÚ A-F Áù¸öÊý×Ö£º"x" ´ú±í a-f ʹÓÃСд×Öĸ±íʾ£¬¶ø "X" ¶ø±íʾ A-F ʹÓôó×Ö×Öĸ±íʾ¡£ÈçÏÂÀý£º

private void TestHex() {
int a = 188;
this.textBox1.Text = "";
this.textBox1.AppendText("a(10) = " + a.ToString() + "\n");
this.textBox1.AppendText("a(16) = " + a.ToString("x") + "\n");
this.textBox1.AppendText("a(16) = " + a.ToString("X") + "\n");
}
¡¡¡¡ÔËÐнá¹ûÈçÏ£º

a(10) = 188
a(16) = bc
a(16) = BC

¡¡¡¡Õâʱºò£¬ÎÒÃÇ¿ÉÄÜÓÐÁíÒ»ÖÖÐèÇ󣬼´ÎªÁËÏÔʾ½á¹ûµÄÕûÆ룬ÎÒÃÇÐèÒª¿ØÖÆÊ®Áù½øÖƱíʾµÄ³¤¶È£¬Èç¹û³¤¶È²»¹»£¬ÓÃÇ°µ¼µÄ 0 Ìî²¹¡£½â¾öÕâ¸öÎÊÌ⣬ÎÒÃÇÖ»ÐèÒªÔÚ¸ñʽ˵Ã÷·û¡°x¡±»òÕß¡°X¡±ºóдÉϱíʾ³¤¶ÈµÄÊý×Ö¾ÍÐÐÁË¡£±ÈÈ磬ҪÏÞÖÆÔÚ 4 ¸ö×Ö·ûµÄ³¤¶È£¬¿ÉÒÔд³É¡°X4¡±¡£ÔÚÉÏÀýÖÐ×·¼ÓÒ»¾ä£º

this.textBox1.AppendText("a(16) = " + a.ToString("X4") + "\n");

¡¡¡¡Æä½á¹û½«Êä³ö a(16) = 00BC¡£
¡¡¡¡ÏÖÔÚ£¬ÎÒÃÇ»¹ÒªËµÒ»ËµÈçºÎ½«Ò»¸ö±íʾʮÁù½øÖÆÊýµÄ×Ö·û´®×ª»»³ÉÕûÐÍ¡£Õâһת»»£¬Í¬ÑùÐèÒª½èÖúÓÚ Parse() ·½·¨¡£ÕâÀÎÒÐèÒª Parse(string, System.Globalization.NumberStyles) ·½·¨¡£µÚÒ»¸ö²ÎÊýÊDZíʾʮÁù½øÖÆÊýµÄ×Ö·û´®£¬Èç¡°AB¡±¡¢¡°20¡±(±íʾʮ½øÖÆµÄ 32) µÈ¡£µÚ¶þ¸ö²ÎÊý System.Globalization.NumberStyles ÊÇÒ»¸öö¾ÙÀàÐÍ£¬ÓÃÀ´±íʾʮÁù½øÖƵÄö¾ÙÖµÊÇ HexNumber¡£Òò´Ë£¬Èç¹ûÎÒÃÇÒª½«¡°AB¡±×ª»»³ÉÕûÐÍ£¬¾ÍÓ¦¸ÃÕâÑùд£ºint b = int.Parse("AB", System.Globalization.NumberStyles.HexNumber)£¬×îºóµÃµ½µÄ b µÄÖµÊÇ 171¡£

9. ÈÕÆÚÐÍÊý¾ÝºÍ³¤ÕûÐÍÊý¾ÝÖ®¼äµÄת»»

¡¡¡¡ÎªÊ²Ã´Òª½«ÈÕÆÚÐÍÊý¾Ýת»»Îª³¤ÕûÐÍÊý¾ÝÄØ£¿Ô­ÒòºÜ¶à£¬µ«¾ÍÎÒ¸öÈËÀ´Ëµ£¬¾­³£½«ËüÓÃÓÚÊý¾Ý¿âµÄÈÕÆÚ´æ´¢¡£ÓÉÓÚ¸÷ÖÖÊý¾Ý¿â¶ÔÈÕÆÚÐ͵Ķ¨ÒåºÍ´¦ÀíÊDz»Ò»ÑùµÄ£¬¸÷ÖÖÓïÑÔ¶ÔÈÕÆÚÐÍÊý¾ÝµÄ¶¨ÒåµÄ´¦ÀíÒ²¸÷²»Ïàͬ£¬ÒòΪ£¬ÎÒÄþÔ¸½«ÈÕÆÚÐÍÊý¾Ýת»»³É³¤ÕûÐÍÔÙ±£´æµ½Êý¾Ý¿âÖС£ËäȻҲ¿ÉÒÔʹÓÃ×Ö·û´®À´±£´æ£¬µ«Ê¹ÓÃ×Ö·û´®Ò²»áÉæ¼°µ½Ðí¶àÎÊÌ⣬ÈçÇøÓòµÈÎÊÌ⣬¶øÇÒ£¬ËüÐèÒª±È±£´æ³¤ÕûÐÍÊý¾Ý¸ü¶àµÄ¿Õ¼ä¡£
¡¡¡¡ÈÕÆÚÐÍÊý¾Ý£¬ÔÚ C# ÖеIJÎÓëÔËËãµÄʱºò£¬Ó¦¸ÃÒ²ÊÇת»»Îª³¤ÕûÐÍÊý¾ÝÀ´ÔËËãµÄ¡£ËüµÄ³¤ÕûÐÍÖµÊÇ×Ô 0001 Äê 1 Ô 1 ÈÕÎçÒ¹ 12:00 ÒÔÀ´Ëù¾­¹ýʱ¼äÒÔ 100 ºÁ΢ÃëΪ¼ä¸ô±íʾʱµÄÊý×Ö¡£Õâ¸öÊýÔÚ C# µÄ DateTime Öб»³ÆΪ Ticks(¿Ì¶È)¡£DateTime ÀàÐÍÓÐÒ»¸öÃûΪ Ticks µÄ³¤ÕûÐÍÖ»¶ÁÊôÐÔ£¬¾Í±£´æ×ÅÕâ¸öÖµ¡£Èç´Ë£¬Òª´ÓÒ»¸ö DataTime ÐÍÊý¾ÝµÃµ½ long ÐÍÖµ¾Í·Ç³£¼òµ¥ÁË£¬Ö»ÐèÒª¶Á³ö DataTime ¶ÔÏóµÄ Ticks Öµ¼´¿É£¬È磺

long longDate = DateTime.Now.Ticks;

¡¡¡¡DateTime µÄ¹¹Ô캯ÊýÖÐÒ²ÌṩÁËÏàÓ¦µÄ£¬´Ó³¤ÕûÐÍÊý¾Ý¹¹Ôì DateTime ÐÍÊý¾ÝµÄº¯Êý£ºDateTime(long)¡£È磺

DateTime theDate = new DateTime(longDate);

¡¡¡¡µ«ÕâÑù¶ÔÓںܶà VB6 ³ÌÐòÔ±À´Ëµ£¬ÊǸøËûÃdzöÁËÒ»µÀÄÑÌ⣬ÒòΪ VB6 ÖеÄÈÕÆÚÐÍÊý¾ÝÄÚ²¿ÊÇÒÔ Double ÐͱíʾµÄ£¬½«Æäת»»Îª³¤ÕûÐͺóµÃµ½µÄ½ö½öÊÇÈÕÆÚ£¬¶øûÓÐʱ¼ä¡£ÈçºÎЭµ÷ÕâÁ½ÖÖÈÕÆÚÀàÐÍÄØ£¿
System.DateTime ÌṩÁË double ToOADate() ºÍ static DateTime FromOADate(double) Á½¸öº¯ÊýÀ´½â¾öÕâ¸öÎÊÌ⡣ǰÕß½«µ±Ç°¶ÔÏó°´Ô­À´µÄ double ÖµÊä³ö£¬ºóÕßÔò´ÓÒ»¸ö double Öµ»ñµÃÒ»¸ö System.DateTime ¶ÔÏó¡£¾ÙÀýÈçÏ£º

private void TestDateTimeLong() {
double doubleDate = DateTime.Now.ToOADate();
DateTime theDate = DateTime.FromOADate(doubleDate);
this.textBox1.Text = "";
this.textBox1.AppendText("Double value of now: " + doubleDate.ToString() + "\n");
this.textBox1.AppendText("DateTime from double value: " + theDate.ToString() + "\n");
}
¡¡¡¡ÔËÐнá¹û£º

Double value of now: 37494.661541713
DateTime from double value: 2002-8-26 15:52:37

10. ¸ñʽ»¯ÈÕÆÚÐÍÊý¾Ý

¡¡¡¡±à³ÌµÄ¹ý³ÌÖУ¬Í¨³£ÐèÒª½«ÈÕÆÚÐÍÊý¾Ý°´ÕÕÒ»¶¨µÄ¸ñʽÊä³ö£¬µ±È»£¬Êä³ö½á¹û¿Ï¶¨ÊÇ×Ö·û´®¡£Îª´Ë£¬ÎÒÃÇÐèҪʹÓà System.DateTime ÀàµÄ ToString() ·½·¨£¬²¢ÎªÆäÖ¸¶¨¸ñʽ×Ö·û´®¡£
¡¡¡¡MSDN ÖУ¬System.Globalization.DateTimeFormatInfo ÀàµÄ¸ÅÊöÀï¶Ôģʽ×Ö·û´®Óзdz£ÏêϸµÄ˵Ã÷£¬Òò´Ë£¬ÕâÀïÎÒÖ»¶Ô³£ÓõÄһЩ¸ñʽ½øÐÐ˵Ã÷£¬Ê×ÏÈÇë¿´ÏÂ±í£º

d ÔÂÖеÄijһÌì һλÊýµÄÈÕÆÚûÓÐÇ°µ¼Áã
dd ÔÂÖеÄijһÌì һλÊýµÄÈÕÆÚÓÐÒ»¸öÇ°µ¼Áã
ddd ÖÜÖÐijÌìµÄËõдÃû³Æ ÔÚ AbbreviatedDayNames Öж¨Òå
dddd ÖÜÖÐijÌìµÄÍêÕûÃû³Æ ÔÚ DayNames Öж¨Òå
M Ô·ÝÊý×Ö Ò»Î»ÊýµÄÔ·ÝûÓÐÇ°µ¼Áã
MM Ô·ÝÊý×Ö Ò»Î»ÊýµÄÔ·ÝÓÐÒ»¸öÇ°µ¼Áã
MMM Ô·ݵÄËõдÃû³Æ ÔÚ AbbreviatedMonthNames Öж¨Òå
MMMM Ô·ݵÄÍêÕûÃû³Æ ÔÚ MonthNames Öж¨Òå
y ²»°üº¬¼ÍÔªµÄÄê·Ý Èç¹û²»°üº¬¼ÍÔªµÄÄê·ÝСÓÚ 10£¬ÔòÏÔʾ²»¾ßÓÐÇ°µ¼ÁãµÄÄê·Ý
yy ²»°üº¬¼ÍÔªµÄÄê·Ý Èç¹û²»°üº¬¼ÍÔªµÄÄê·ÝСÓÚ 10£¬ÔòÏÔʾ¾ßÓÐÇ°µ¼ÁãµÄÄê·Ý
yyyy °üÀ¨¼ÍÔªµÄËÄλÊýµÄÄê·Ý
h 12 СʱÖƵÄСʱ һλÊýµÄСʱÊýûÓÐÇ°µ¼Áã
hh 12 СʱÖƵÄСʱ һλÊýµÄСʱÊýÓÐÇ°µ¼Áã
H 24 СʱÖƵÄСʱ һλÊýµÄСʱÊýûÓÐÇ°µ¼Áã
HH 24 СʱÖƵÄСʱ һλÊýµÄСʱÊýÓÐÇ°µ¼Áã
m ·ÖÖÓ Ò»Î»ÊýµÄ·ÖÖÓÊýûÓÐÇ°µ¼Áã
mm ·ÖÖÓ Ò»Î»ÊýµÄ·ÖÖÓÊýÓÐÒ»¸öÇ°µ¼Áã
s Ãë һλÊýµÄÃëÊýûÓÐÇ°µ¼Áã
ss Ãë һλÊýµÄÃëÊýÓÐÒ»¸öÇ°µ¼Áã

¡¡¡¡ÎªÁ˱ãÓÚ´ó¼ÒµÄÀí½â£¬²»·ÁÊÔÊÔÏÂÃæµÄ³ÌÐò£º

private void TestDateTimeToString() {
DateTime now = DateTime.Now;
string format;
this.textBox1.Text = "";
format = "yyyy-MM-dd HH:mm:ss";
this.textBox1.AppendText(format + ": " + now.ToString(format) + "\n");
format = "yyÄêMÈÕdÈÕ";
this.textBox1.AppendText(format + ": " + now.ToString(format) + "\n");
}
¡¡¡¡Õâ¶Î³ÌÐò½«Êä³ö½á¹û£º

yyyy-MM-dd HH:mm:ss: 2002-08-26 17:03:04
yyÄêMÈÕdÈÕ: 02Äê8ÈÕ26ÈÕ

¡¡¡¡Õâʱºò£¬ÓÖ³öÏÖÒ»¸öÎÊÌ⣬Èç¹ûÒªÊä³öµÄÎı¾ÐÅÏ¢Öаüº¬¸ñʽ×Ö·ûÔõô°ì£¿Èç

format = "year: yyyy, month: MM, day: dd";
this.textBox1.AppendText(now.ToString(format) + "\n");

¡¡¡¡½«Êä³ö£º

2ear: 2002, 4onÏÂ5: 08, 26a2: 26

¡¡¡¡Õâ²¢²»ÊÇÎÒÏëÒªµÄ½á¹û£¬Ôõô°ìÄØ£¿Óа취¨D¨D

format = "\"year\": yyyy, \'month\': MM, \'day\': dd";
this.textBox1.AppendText(now.ToString(format) + "\n");

¡¡¡¡¿´£¬Õâ´ÎÔËÐнá¹û¶ÔÁË£º

year: 2002, month: 08, day: 26

¡¡¡¡¿ÉÒÔ¿´³ö£¬Ö»ÐèҪʹÓõ¥ÒýºÅ»òÕßË«ÒýºÅ½«Îı¾ÐÅÏ¢À¨ÆðÀ´¾ÍºÃ¡£

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