【结帖】字符串截取**

tfb

在平台上使用下面这样的方法截取字符串提示参数过多, 平台中哪个才是字符串截取函数呢?
s:=sysutils.StrCopy(Itembh,2,1);

jiahaiminghr

function Substring(startIndex: Longint; length: Longint): string; overload;
  function Substring(startIndex: Longint): string; overload;



NameSpace: System
--------------------------------------------------------------------------------
String = class(Object)
private
  m_arrayLength: Longint;
  m_firstChar: Char;
  m_stringLength: Longint;
  TrimBoth: Longint;
  TrimHead: Longint;
  TrimTail: Longint;
  WhitespaceChars: array of Char;
  static class constructor create; overload;
  procedure AppendInPlace(value: Char; repeatCount: Longint; currentLength: Longint); overload;
  procedure AppendInPlace(value: string; currentLength: Longint); overload;
  procedure AppendInPlace(value: string; startIndex: Longint; count: Longint; currentLength: Longint); overload;
  procedure AppendInPlace(value: Char^ ; count: Longint; currentLength: Longint); overload;
  procedure AppendInPlace(value: array of Char; start: Longint; count: Longint; currentLength: Longint); overload;
  procedure AppendInPlace(value: Char; currentLength: Longint); overload;
  procedure ClearPostNullChar; overload;
  static function ConcatArray(values: array of string; totalLength: Longint): string; overload;
  static function CopyArrayOnNull(values: array of string; totalLength: Longint): array of string; overload;
  procedure CopyToByteArray(sourceIndex: Longint; destination: array of Byte; destinationIndex: Longint; charCount: Longint); overload;
  static function CreateFromCharArray(array: array of Char; start: Longint; count: Longint): string; overload;
  static function CreateString(value: Shortint^ ; startIndex: Longint; length: Longint; enc: Text.Encoding): string; overload;
  static function CreateStringFromASCII(bytes: array of Byte; startIndex: Longint; length: Longint): string; overload;
  function EndsWith(value: Char): Boolean; overload;
  static function FastAllocateString(length: Longint): string; overload;
  static procedure FillString(dest: string; destPos: Longint; src: string); overload;
  static procedure FillStringArray(dest: string; stringStart: Longint; array: array of Char; charStart: Longint; count: Longint); overload;
  static procedure FillStringChecked(dest: string; destPos: Longint; src: string); overload;
  static procedure FillStringEx(dest: string; destPos: Longint; src: string; srcLength: Longint); overload;
  static procedure FillSubstring(dest: string; destPos: Longint; src: string; startPos: Longint; count: Longint); overload;
  static function GetStringForStringBuilder(value: string; capacity: Longint): string; overload;
  procedure InsertInPlace(index: Longint; value: string; repeatCount: Longint; currentLength: Longint; requiredLength: Longint); overload;
  static procedure InternalCopy(src: string; dest: array of Byte; len: Longint); overload;
  static function InternalCopy(str: string): string; overload;
  static procedure InternalCopy(src: string; dest: Integer; len: Longint); overload;
  procedure InternalCopyTo(sourceIndex: Longint; destination: array of Char; destinationIndex: Longint; count: Longint); overload;
  function InternalGetChar(index: Longint): Char; overload;
  function InternalLength: Longint; overload;
  static procedure InternalMemCpy(src: string; srcOffset: Longint; dst: string; destOffset: Longint; len: Longint); overload;
  procedure InternalSetCharNoBoundsCheck(index: Longint; value: Char); overload;
  function IsFastSort: Boolean; overload;
  static function nativeCompareOrdinal(strA: string; strB: string; bIgnoreCase: Boolean): Longint; overload;
  static function nativeCompareOrdinalEx(strA: string; indexA: Longint; strB: string; indexB: Longint; count: Longint): Longint; overload;
  static function nativeCompareOrdinalWC(strA: string; strBChars: Char^ ; bIgnoreCase: Boolean; success: Boolean): Longint; overload;
  static procedure nativeSmallCharToUpper(strIn: string; strOut: string); overload;
  procedure NullTerminate; overload;
  function PadHelper(totalWidth: Longint; paddingChar: Char; isRightPadded: Boolean): string; overload;
  procedure ReplaceCharInPlace(oldChar: Char; newChar: Char; startIndex: Longint; count: Longint; currentLength: Longint); overload;
  static procedure revmemcpyimpl(src: Byte^ ; dest: Byte^ ; len: Longint); overload;
  procedure SetChar(index: Longint; value: Char); overload;
  procedure SetLength(newLength: Longint); overload;
  static function SmallCharToUpper(strA: string): string; overload;
  function System.Collections.IEnumerable.GetEnumerator: Collections.IEnumerator; maFinal; virtual; overload;
  function System.IConvertible.ToBoolean(provider: IFormatProvider): Boolean; maFinal; virtual; overload;
  function System.IConvertible.ToByte(provider: IFormatProvider): Byte; maFinal; virtual; overload;
  function System.IConvertible.ToChar(provider: IFormatProvider): Char; maFinal; virtual; overload;
  function System.IConvertible.ToDateTime(provider: IFormatProvider): DateTime; maFinal; virtual; overload;
  function System.IConvertible.ToDecimal(provider: IFormatProvider): Decimal; maFinal; virtual; overload;
  function System.IConvertible.ToDouble(provider: IFormatProvider): Double; maFinal; virtual; overload;
  function System.IConvertible.ToInt16(provider: IFormatProvider): Smallint; maFinal; virtual; overload;
  function System.IConvertible.ToInt32(provider: IFormatProvider): Longint; maFinal; virtual; overload;
  function System.IConvertible.ToInt64(provider: IFormatProvider): Int64; maFinal; virtual; overload;
  function System.IConvertible.ToSByte(provider: IFormatProvider): Shortint; maFinal; virtual; overload;
  function System.IConvertible.ToSingle(provider: IFormatProvider): Real; maFinal; virtual; overload;
  function System.IConvertible.ToType(type: Type; provider: IFormatProvider): TObject; maFinal; virtual; overload;
  function System.IConvertible.ToUInt16(provider: IFormatProvider): Word; maFinal; virtual; overload;
  function System.IConvertible.ToUInt32(provider: IFormatProvider): Longword; maFinal; virtual; overload;
  function System.IConvertible.ToUInt64(provider: IFormatProvider): Int64; maFinal; virtual; overload;
  function TrimHelper(trimChars: array of Char; trimType: Longint): string; overload;
  property ArrayLength: Longint; readonly;
  property Capacity: Longint; readonly;
public
  Empty: string;
  constructor create(value: Shortint^ ); overload;
  constructor create(value: Shortint^ ; startIndex: Longint; length: Longint); overload;
  constructor create(value: Shortint^ ; startIndex: Longint; length: Longint; enc: Text.Encoding); overload;
  constructor create(value: array of Char; startIndex: Longint; length: Longint); overload;
  constructor create(value: array of Char); overload;
  constructor create(c: Char; count: Longint); overload;
  constructor create(value: Char^ ); overload;
  constructor create(value: Char^ ; startIndex: Longint; length: Longint); overload;
  function Clone: TObject; maFinal; virtual; overload;
  static function Compare(strA: string; indexA: Longint; strB: string; indexB: Longint; length: Longint): Longint; overload;
  static function Compare(strA: string; indexA: Longint; strB: string; indexB: Longint; length: Longint; ignoreCase: Boolean): Longint; overload;
  static function Compare(strA: string; indexA: Longint; strB: string; indexB: Longint; length: Longint; ignoreCase: Boolean; culture: Globalization.CultureInfo): Longint; overload;
  static function Compare(strA: string; strB: string): Longint; overload;
  static function Compare(strA: string; strB: string; ignoreCase: Boolean): Longint; overload;
  static function Compare(strA: string; strB: string; ignoreCase: Boolean; culture: Globalization.CultureInfo): Longint; overload;
  static function CompareOrdinal(strA: string; indexA: Longint; strB: string; indexB: Longint; length: Longint): Longint; overload;
  static function CompareOrdinal(strA: string; strB: string): Longint; overload;
  function CompareTo(strB: string): Longint; overload;
  function CompareTo(value: TObject): Longint; maFinal; virtual; overload;
  static function Concat(values: array of string): string; overload;
  static function Concat(arg0: TObject): string; overload;
  static function Concat(arg0: TObject; arg1: TObject): string; overload;
  static function Concat(arg0: TObject; arg1: TObject; arg2: TObject): string; overload;
  static function Concat(arg0: TObject; arg1: TObject; arg2: TObject; arg3: TObject): string; overload;
  static function Concat(args: array of TObject): string; overload;
  static function Concat(str0: string; str1: string): string; overload;
  static function Concat(str0: string; str1: string; str2: string): string; overload;
  static function Concat(str0: string; str1: string; str2: string; str3: string): string; overload;
  static function Copy(str: string): string; overload;
  procedure CopyTo(sourceIndex: Longint; destination: array of Char; destinationIndex: Longint; count: Longint); overload;
  function EndsWith(value: string): Boolean; overload;
  function Equals(obj: TObject): Boolean; override; overload;
  function Equals(value: string): Boolean; overload;
  static function Equals(a: string; b: string): Boolean; overload;
  static function Format(format: string; arg0: TObject): string; overload;
  static function Format(format: string; arg0: TObject; arg1: TObject): string; overload;
  static function Format(format: string; arg0: TObject; arg1: TObject; arg2: TObject): string; overload;
  static function Format(format: string; args: array of TObject): string; overload;
  static function Format(provider: IFormatProvider; format: string; args: array of TObject): string; overload;
  function GetEnumerator: CharEnumerator; overload;
  function GetHashCode: Longint; override; overload;
  function GetTypeCode: TypeCode; maFinal; virtual; overload;
  function IndexOf(value: string; startIndex: Longint; count: Longint): Longint; overload;
  function IndexOf(value: Char): Longint; overload;
  function IndexOf(value: Char; startIndex: Longint): Longint; overload;
  function IndexOf(value: Char; startIndex: Longint; count: Longint): Longint; overload;
  function IndexOf(value: string): Longint; overload;
  function IndexOf(value: string; startIndex: Longint): Longint; overload;
  function IndexOfAny(anyOf: array of Char; startIndex: Longint; count: Longint): Longint; overload;
  function IndexOfAny(anyOf: array of Char): Longint; overload;
  function IndexOfAny(anyOf: array of Char; startIndex: Longint): Longint; overload;
  function Insert(startIndex: Longint; value: string): string; overload;
  static function Intern(str: string): string; overload;
  static function IsInterned(str: string): string; overload;
  static function Join(separator: string; value: array of string): string; overload;
  static function Join(separator: string; value: array of string; startIndex: Longint; count: Longint): string; overload;
  function LastIndexOf(value: string): Longint; overload;
  function LastIndexOf(value: string; startIndex: Longint): Longint; overload;
  function LastIndexOf(value: string; startIndex: Longint; count: Longint): Longint; overload;
  function LastIndexOf(value: Char): Longint; overload;
  function LastIndexOf(value: Char; startIndex: Longint): Longint; overload;
  function LastIndexOf(value: Char; startIndex: Longint; count: Longint): Longint; overload;
  function LastIndexOfAny(anyOf: array of Char): Longint; overload;
  function LastIndexOfAny(anyOf: array of Char; startIndex: Longint): Longint; overload;
  function LastIndexOfAny(anyOf: array of Char; startIndex: Longint; count: Longint): Longint; overload;
  static function op_Equality(a: string; b: string): Boolean; overload;
  static function op_Inequality(a: string; b: string): Boolean; overload;
  function PadLeft(totalWidth: Longint; paddingChar: Char): string; overload;
  function PadLeft(totalWidth: Longint): string; overload;
  function PadRight(totalWidth: Longint; paddingChar: Char): string; overload;
  function PadRight(totalWidth: Longint): string; overload;
  function Remove(startIndex: Longint; count: Longint): string; overload;
  function Replace(oldValue: string; newValue: string): string; overload;
  function Replace(oldChar: Char; newChar: Char): string; overload;
  function Split(separator: array of Char): array of string; overload;
  function Split(separator: array of Char; count: Longint): array of string; overload;
  function StartsWith(value: string): Boolean; overload;
  function Substring(startIndex: Longint; length: Longint): string; overload;
  function Substring(startIndex: Longint): string; overload;
  function ToCharArray: array of Char; overload;
  function ToCharArray(startIndex: Longint; length: Longint): array of Char; overload;
  function ToLower(culture: Globalization.CultureInfo): string; overload;
  function ToLower: string; overload;
  function ToString(provider: IFormatProvider): string; maFinal; virtual; overload;
  function ToString: string; override; overload;
  function ToUpper(culture: Globalization.CultureInfo): string; overload;
  function ToUpper: string; overload;
  function Trim(trimChars: array of Char): string; overload;
  function Trim: string; overload;
  function TrimEnd(trimChars: array of Char): string; overload;
  function TrimStart(trimChars: array of Char): string; overload;
  property Chars[Longint]: Char; readonly;
  property Length: Longint; readonly;
end;

tfb

用 Midstr（）函数了。

请结贴吧！