Delphi中常用字符串处理函数

1.copy(str,pos,num) 从str字符串的pos处开始,截取num个字符的串返回.

假设str为'abcdef',copy(str,3,2)='cd',copy(str,4,10)='def'

2.concat(str1,str2{,strn}) 把各自变量连接起来,返回连接后的字符串(长度不能超过255)

3.length(str) 返回str的字符个数,即其长度.

4.pos(obj,target) 在target字符串中找出第一个出现obj的第一个字符位置,如果找不到,返回0.

5.AnsiStrLastChar('你好')结果是“好”。如果有半个汉字出现,返回这半个汉字。二者字符串长度分别为2和1。

6.CompareStr - 区分大小写

7.CompareText - 不区分大小写

8.StringReplace(const S, OldPattern, NewPattern: string;Flags: TReplaceFlags): string;

字符串替换函数，需要引用SysUtils单元

rfReplaceAll：全部替换

rfIgnoreCase：忽略大小写

使用方法Lg：

　　str：＝＇01231142211 ：655767＇；//需要把：替换成----

s:=StringReplace(str,'：','----',[rfReplaceAll]);

For Example：

var

aStr: String;

begin

aStr := 'This is a book, not a pen!';

ShowMessage(StringReplace (aStr, 'a', 'two', [])); //This is two book, not a pen!只替换了第一个符合的字

ShowMessage(StringReplace (aStr, 'a', 'two', [rfReplaceAll]));

//This is two book, not two pen!替换了所有符合的字

aStr := 'This is a book, not A pen!';

ShowMessage(StringReplace (aStr, 'a', 'two', [rfReplaceAll])); //This is two book, not A pen!只替换了符合的字(小写a)

ShowMessage(StringReplace (aStr, 'a', 'two', [rfReplaceAll, rfIgnoreCase])); //This is two book, not two pen!不管大小写替换了所有符合的字

end;

9.delete 是删除一个 字符串中的 某部分字符

用法是 delete(str,//被删除的字符串

index,//从第几个字符开始删除

count //删除几个

);

Delete(S, 2, 2); 就是从S中的第二个开始删除，删除2个字符即2、3.所以结果是145.

////////////////////////////////////////////////////////

LEFTSTR, MIDSTR, RIGHTSTR的介绍

这几个函数都包含在StrUtils中，所以需要uses StrUtils;

假设字符串是 Dstr := ’Delphi is the BEST’, 那么

LeftStr(Dstr, 5) := ’Delph’

MidStr(Dstr, 6, 7) := ’i is th’

RightStr(Dstr, 6) := ’e BEST’

8.{判断字符是否是数字}

function IsDigit(ch: char): boolean;

begin

Result := ch in ['0'..'9'];

end;

9、{判断字符是否是大写字符}

function IsUpper(ch: char): boolean;

begin

Result := ch in ['A'..'Z'];

end;

10、{判断字符是否是小写字符}

function IsLower(ch: char): boolean;

begin

Result := ch in ['a'..'z'];

end;

11、{转换为大写字符}

function ToUpper(ch: char): char;

begin

Result := chr(ord(ch) and $DF);

end;

12、{转换为小写字符}

function ToLower(ch: char): char;

begin

Result := chr(ord(ch) or $20);

end;

{ Capitalizes first letter of every word in s }

function Proper(const s: string): string;

var

i: Integer;

CapitalizeNextLetter: Boolean;

begin

Result := LowerCase(s);

CapitalizeNextLetter := True;

for i := 1 to Length(Result) do

begin

if CapitalizeNextLetter and IsLower(Result[i]) then

Result[i] := ToUpper(Result[i]);

CapitalizeNextLetter := Result[i] = ' ';

end;

end;

////////////////////////////////////////////////////////////

13.{返回两个子字符串之间字符的个数}

Function p2pcount( s, ss1, ss2 : string ): integer;

var i, j, slen : integer;

begin

i := pos( ss1, s );

j := pos( ss2, s );

slen := Length(ss2);

if j >= i then Result := j - i + slen else Result := 0;

end;

14.{更快速的字符查询,快40%}

function ScanStr(ToScan: PChar; Sign: Char):PChar;

begin

Result:= nil;

if ToScan <> nil then

while (ToScan^ <> #0) do begin

if ToScan^ = Sign then begin

Result:= ToScan;

break;

end;

inc(ToScan);

end;

end;

/////////////////////////////

15.替换字符串中子串的函数,他可以从字符串中找出指定子串,并替换为另一子串。

function replacing(S,source,target:string):string;

var site,StrLen:integer;

begin

{source在S中出现的位置}

site:=pos(source,s);

{source的长度}

StrLen:=length(source);

{删除source字符串}

delete(s,site,StrLen);

{插入target字符串到S中}

insert(target,s,site);

{返回新串}

replacing:=s;

end;

///////////////////////

另两个替换字符串中子串的函数

function repl_substr( sub1, sub2, s: string ): string;

var i: integer;

begin

repeat

i := pos( sub1, s ) ;

if i > 0 then begin

delete( s, i, Length(sub1));

insert( sub2, s, i );

end;

until i < 1;

Result := s;

end;

function ReplaceText(const S,ReplacePiece,ReplaceWith: String):String;

Var Position: Integer;

TempStr: String;

begin

Position := Pos(ReplacePiece,S);

if Position > 0 then Begin

TempStr := S;

Delete(TempStr,1,Position-1+Length(ReplacePiece));

Result :=

Copy(S,1,Position-1)+ReplaceWith+ReplaceText(TempStr,ReplacePiece,ReplaceWith)

End else Result := S;

end;

////////////////////////

替换全部子字符串的函数

function ReplaceSub(str, sub1, sub2: String): String;

var

aPos: Integer;

rslt: String;

begin

aPos := Pos(sub1, str);

rslt := '';

while (aPos <> 0) do begin

rslt := rslt + Copy(str, 1, aPos - 1) + sub2;

Delete(str, 1, aPos + Length(sub1));

aPos := Pos(sub1, str);

end;

Result := rslt + str;

end;

/////////////////////////

在字符串左右填充指定数量的指定字符

function UT_PadString(inString :string; maxLength :integer; padChar :char;

left :boolean) :string;

begin

result := inString;

while (Length(result) < maxLength) do

if (left) then

result := padChar + result

else

result := result + padChar;

end;

/////////////////////////////////////

提取字符串中指定子字符串前的字符串

Function Before ( string ; Var S:string ) : string ; < /span>

Var

F : Word ;

begin

F := POS (Src,S) ;

if F=0 then

Before := S

else

Before := COPY(S,1,F-1) ;

end ;

//////////////////////////////////

提取字符串中指定子字符串后的字符串

Function After ( string ; Var S:string ) : string ; < /span>

Var

F : Word ;

begin

F := POS (Src,S) ;

if F=0 then

After := ''

else

After := COPY(S,F+length(src),length(s)) ;

end ;

////////////////////////////////////

判断字符串是否可以转换为整数

function IsIntStr(const S: string): boolean;

begin

Result:=StrToIntDef(S,0)=StrToIntDef(S,1);

end;

//////////////////////////////////////

从字符串中删除指定字符串

procedure RemoveInvalid(what, where: string): string;

var

tstr: string;

begin

tstr:=where;

while pos(what, tstr)>0 do

tstr:=copy(tstr,1,pos(what,tstr)-1) +

copy(tstr,pos(what,tstr)+length(tstr),length(tstr));

Result:=tstr;

end;

用法:

NewStr:=RemoveInvalid('<invalid>','This <invalid> is my string and I wan to

remove the word <invalid>');

///////////////////////////////////////////

根据某个字符分割字符串的函数

procedure SeparateTerms(s : string;Separator : char;Terms : TStringList);

{ This browses a string and divide it into terms whenever the given

separator is found. The separators will be removed }

var

hs : string;

p : integer;

begin

Terms.Clear; // First remove all remaining terms

if Length(s)=0 then // Nothin' to separate

Exit;

p:=Pos(Separator,s);

while P<>0 do

begin

hs:=Copy(s,1,p-1); // Copy term

Terms.Add(hs); // Add to list

Delete(s,1,p); // Remove term and separator

p:=Pos(Separator,s); // Search next separator

end;

if Length(s)>0 then

Terms.Add(s); // Add remaining term

end;

==========

= 用 法

==========

var

Terms : TStringList;

i : integer;

const

TestStr = '1st term;2nd term;3rd term';

begin

Terms:=TStringList.Create;

SeparateTerms(TestStr,';',Terms);

for i:=0 to terms.Count-1 do

ShowMessage(Terms.Strings[i]);

Terms.Free;

end;

/////////////////////////////

根据一组字符分割字符串的函数

type

Charset = set of Char;

var

f : Text;

s : String;

procedure WriteStringSplitted(var s: String; Separators: Charset);

var

a,e : Integer; {anfang und ende des w鰎tchens}

begin

a := 1;

for e := 1 to Length(s) do

if s[e] in Separators then begin

WriteLn(Copy(s, a, e-a));

a := e + 1;

end;

WriteLn(Copy(s, a, e-a+1));

end;

begin

Assign(f, 'c:/dingsbums/text.txt');

Reset(f);

while not EOF(f) do begin

ReadLn(f,s);

WriteStringSplitted(s, [':', ',']);

end;

Close(f);

end.

//////////////////////////////////////////////////

{===============================================================}

{ 函数 : RESULTSTRING = HexToBin(HEXSTRING)

{ 目的 : 把十六进制字符串转换为二进制字符串

{

{===============================================================}

{ 函数 : RESULTINTEGER = HexCharToInt(HEXCHAR)

{ 目的 : 转换一个十六进制字符为整数

{===============================================================}

{ 函数 : RESULTSTRING = HexCharToBin(HEXCHAR)

{ 目的 : 转换一个十六进制字符为二进制字符串

{===============================================================}

{ 函数 : RESULTINTEGER = Pow(BASE,POWER)

{ 目的 : 指数函数

{===============================================================}

{ 函数 : RESULTINTEGER = BinStrToInt(BINSTRING)

{ 目的 : 把二进制字符串转换为整数

{===============================================================}

{ 函数 : RESULTSTRING = DecodeSMS7Bit (PDUSTRING)

{ 目的 : 解码一个7-bit SMS (GSM 03.38) 为ASCII码

{===============================================================}

{ 函数 : RESULTSTRING = ReverseStr (SOURCESTRING)

{ 目的 : 反转一个字符串

{===============================================================}

unit BinHexTools;

interface

function HexToBin(HexNr : string): string;

function HexCharToInt(HexToken : char):Integer;

function HexCharToBin(HexToken : char): string;

function pow(base, power: integer): integer;

function BinStrToInt(BinStr : string) : integer;

function DecodeSMS7Bit(PDU : string):string;

function ReverseStr(SourceStr : string) : string;

implementation

uses sysutils, dialogs;

function HexCharToInt(HexToken : char):Integer;

begin

{if HexToken>#97 then HexToken:=Chr(Ord(HexToken)-32);

{ use lowercase aswell }

Result:=0;

if (HexToken>#47) and (HexToken<#58) then { chars 0....9 }

Result:=Ord(HexToken)-48

else if (HexToken>#64) and (HexToken<#71) then { chars A....F }

Result:=Ord(HexToken)-65 + 10;

end;

function HexCharToBin(HexToken : char): string;

var DivLeft : integer;

begin

DivLeft:=HexCharToInt(HexToken); { first HEX->BIN }

Result:='';

{ Use reverse dividing }

repeat { Trick; divide by 2 }

if odd(DivLeft) then { result = odd ? then bit = 1 }

Result:='1'+Result { result = even ? then bit = 0 }

else

Result:='0'+Result;

DivLeft:=DivLeft div 2; { keep dividing till 0 left and length = 4 }

until (DivLeft=0) and (length(Result)=4); { 1 token = nibble = 4 bits }

end;

function HexToBin(HexNr : string): string;

{ only stringsize is limit of binnr }

var Counter : integer;

begin

Result:='';

for Counter:=1 to length(HexNr) do

Result:=Result+HexCharToBin(HexNr[Counter]);

end;

function pow(base, power: integer): integer;

var counter : integer;

begin

Result:=1;

for counter:=1 to power do

Result:=Result*base;

end;

function BinStrToInt(BinStr : string) : integer;

var counter : integer;

begin

if length(BinStr)>16 then

raise ERangeError.Create(#13+BinStr+#13+

'is not within the valid range of a 16 bit binary.'+#13);

Result:=0;

for counter:=1 to length(BinStr) do

if BinStr[Counter]='1' then

Result:=Result+pow(2,length(BinStr)-counter);

end;

function DecodeSMS7Bit(PDU : string):string;

var OctetStr : string;

OctetBin : string;

Charbin : string;

PrevOctet: string;

Counter : integer;

Counter2 : integer;

begin

PrevOctet:='';

Result:='';

for Counter:=1 to length(PDU) do

begin

if length(PrevOctet)>=7 then { if 7 Bit overflow on previous }

begin

if BinStrToInt(PrevOctet)<>0 then

Result:=Result+Chr(BinStrToInt(PrevOctet))

else Result:=Result+' ';

PrevOctet:='';

end;

if Odd(Counter) then { only take two nibbles at a time }

begin

OctetStr:=Copy(PDU,Counter,2);

OctetBin:=HexToBin(OctetStr);

Charbin:='';

for Counter2:=1 to length(PrevOctet) do

Charbin:=Charbin+PrevOctet[Counter2];

for Counter2:=1 to 7-length(PrevOctet) do

Charbin:=OctetBin[8-Counter2+1]+Charbin;

if BinStrToInt(Charbin)<>0 then Result:=Result+Chr(BinStrToInt(CharBin))

else Result:=Result+' ';

PrevOctet:=Copy(OctetBin,1,length(PrevOctet)+1);

end;

end;

end;

function ReverseStr(SourceStr : string) : string;

var Counter : integer;

begin

Result:='';

for Counter:=1 to length(SourceStr) do

Result:=SourceStr[Counter]+Result;

end;

end.

转自https://www.cnblogs.com/hhmm99/p/10613708.html