Chapter String Introdution

Chapter : STRING Slide 2 9:06:37 AM 1. Introduction • String and character processing capabilities – Text editors – Word processors… • Expand from previous chapters – Class String and type char – Class StringBuilder Slide 3 9:06:37 AM Fundamentals of Characters and Strings • Importance of characters – Character constants • Character code • Unicode character set – String • Object of class String in System namespace • Consist of characters Slide 4 9:06:37 AM String Constructors • Class String – Provides eight constructors for initialing strings string file = "C:\\MyFolder\\MySubFolder\\MyFile.txt"; string file = @"C:\MyFolder\MySubFolder\MyFile.txt"; Slide 5 9:06:37 AM Introduction • String and character processing capabilities – Text editors – Word processors… • Expand from previous chapters – Class String and type Char (System namespace) – Class StringBuilder (System.Text namespace) Slide 7 9:06:37 AM String class: Initialing strings Using constructors of String class: new String (char[ ] chuoi_ki_tu); new String (char[ ] chuoi_ki_tu, int vi_tri_bat_dau_lay, int so_ki_tu); new String (char ki_tu, int so_lan_lap); string output; string originalString, string1, string2, string3, string4; char[] characterArray = { 'b', 'i', 'r', 't', 'h', ' ', 'd', 'a', 'y' }; // string initialization originalString = "Welcome to C# programming!"; string1 = originalString; string2 = new string( characterArray ); string3 = new string( characterArray, 6, 3 ); string4 = new string( 'C', 5 ); output = "string1 = " + "\"" + string1 + "\"\n" + "string2 = " + "\"" + string2 + "\"\n" + "string3 = " + "\"" + string3 + "\"\n" + "string4 = " + "\"" + string4 + "\"\n"; StringCons tructor.cs Slide 10 9:06:37 AM String Length Property and CopyTo Method • Length property – Returns the length of the string • CopyTo – Copies specified number of characters into a char array CopyTo ( int sourceIndex, array[] destination, int destinationIndex, int count ) Copy To: tại 1 ví trí trên chuỗi gốc (sourceIndex, ), lấy một số ký tự (count), Copy tới một vị trí (destinationIndex) , trên một bảng dãy ký tự Unicode destination; StringMethods string string1, output; char[ ] characterArray; string1 = "hello there"; characterArray = new char[ 10 ]; string1.CopyTo( 0, characterArray, 2, 5 ); output += "\nThe character array is: "; for ( int i = 0 ; i < characterArray.Length; i++ ) output += characterArray[ i ]; h e l l o [...]... objectString.LastIndexOf (char[] value, int startIndex) Working With String 1 Bool MyString.StartsWith( s ) 2 Bool MyString.EndsWith( s ) 3 string MyString.Substring ( int startIndex, int length ) 4 MyString.ToLower( ) 5 MyString.ToUpper( ) 6 MyString.ToString( ) 7 MyString.Trim( ) 8 MyString.TrimEnd( ) 9 MyString.TrimStart ( ) StartsWith(strA) strA=“Working with String strB=“w” strA.StartsWith("T") =F strA.StartsWith(strB)... value: • int String. Compare (String s1, String s2) • int String. Compare (String s1, String s2, bool ignoreCase) • int objectString.CompareTo (String s) Comparing Strings • • • • String s1, s2; hi car S1= Car ; Return -1: S1 < S2 < 1: Return -1: S1 > S2 Car Cat S2= hello ; S1.CompareTo(s2) Locating Characters in Strings • IndexOf methods: Reports the index of the first occurrence of a String, or one... int objectString.LastIndexOf (string value) • int objectString.LastIndexOf (string value, int startIndex) • int objectString.LastIndexOf (string value, int startIndex, int limit) • int objectString.LastIndexOf (char value) • int objectString.LastIndexOf (char value, int startIndex) – LastIndexOfAny method: report the last occurrence • int objectString.LastIndexOf (char[] value) • int objectString.LastIndexOf... with String • strB = "w“ strA.IndexOf("w") =8 strA.IndexOf(strB.ToUpper) =0 strA.IndexOf(strB.ToUpper, 3) = -1 strA.IndexOf(“ “, 3) =7 Example • strA=“Working with String • strB = "w“ strA.Substring(8) = with String strA.Substring(8, 4) = with strA.Substring(strA.IndexOf("S")) = String Replace String Methods • Method Replace (phương thức thay thế chuỗi) – Original string remain unchanged – String. ..Comparing Strings • String comparison – Greater than (1) – Less than (-1) – Equal (0) • Method Equals – Test objects for equality – Return a Boolean – Uses lexicographical comparison Comparing Strings • Method Equals: test objects for equality – Return a bool value: true if equal • bool String. Equals (String s1, String s2) • bool objectString.Equals (String s) • Method CompareTo:... or more characters, within this string – IndexOf(char value) – IndexOf(char value, int StartIndex) – IndexOf (string value) – IndexOf (string value, int StartIndex) –; Locating Characters in Strings IndexOfAny method: report the first occurrence int objectString.IndexOfAny (char[] value) int objectString.IndexOfAny (char[] value, int startIndex) Locating Characters in Strings – LastIndexOf method: report... String Replace String Methods • Method Replace (phương thức thay thế chuỗi) – Original string remain unchanged – String objectString.Replace (String oldValue, String newValue) – String objectString.Replace (char oldValue, char newValue) Tách chuỗi • Sử dụng phương thức Split() của lớp String: phân tích một chuỗi ra thành các chuỗi con dựa vào ký tự phân cách • Cú pháp: Split (char[] sign), hàm trả về một... Split(), chúng ta truyền vào một mảng các ký tự phân cách, các ký tự này được dùng để chia các từ trong chuỗi • Ví dụ: Tách chuỗi “Nguyễn Văn An” dựa vào khoảng trắng Ví dụ string s1 = “Nguyễn Văn An"; char[ ] space = {' '}; string[ ] s; s = s1.Split (space); //tham so truyen la mang ky tu txtHo.Text = s[0]; txtTen.Text = s[s.Length - 1]; for ( int i=1; i . char – Class StringBuilder Slide 3 9:06: 37 AM Fundamentals of Characters and Strings • Importance of characters – Character constants • Character code • Unicode character set – String • Object. type Char (System namespace) – Class StringBuilder (System.Text namespace) Slide 7 9:06: 37 AM String class: Initialing strings Using constructors of String class: new String (char[ ] chuoi_ki_tu); new. of class String in System namespace • Consist of characters Slide 4 9:06: 37 AM String Constructors • Class String – Provides eight constructors for initialing strings string file = " ;C: \MyFolder\MySubFolder\MyFile.txt"; string