string replace???

**Cmdr0Sunburn** · Oct 8th, 2002, 08:51 PM

any one know if msvc++ has a string replace function. btw im also trying to make one converted from assembly and is impossable, so i need to know if c++ has a default one.
btw if any one wants to help me convert my assembly string replace to c++ please tell me and ill post assembly code, basicly i want to see if the c++ compiler can optimize my assembly convert. i cant seem to get the binary string of bytes compare to work.

**parksie** · Oct 9th, 2002, 06:58 AM

Look up std::string::replace

**made_of_asp** · Oct 9th, 2002, 07:31 AM

This one is for single char only but doesnt require string class...

PHP Code:


char* VirtualReplace(char* pString, char src, char tg)

{

    //variables

    char* rc = (char*)calloc(strlen(pString) + 1, sizeof(char));

    unsigned long i = 0;



    while(*pString)

    {

        //check for replacive

        rc[i] = (*pString == src) ? tg : *pString;



        //increase by 1

        i++;

        *pString++;

    }



    return rc;



    //free the memory

    free(rc);

}

**parksie** · Oct 9th, 2002, 07:40 AM

Originally posted by made_of_asp
This one is for single char only but doesnt require string class...

PHP Code:

char* VirtualReplace(char* pString, char src, char tg) { //variables char* rc = (char*)calloc(strlen(pString) + 1, sizeof(char)); unsigned long i = 0; while(*pString) { //check for replacive rc[i] = (*pString == src) ? tg : *pString; //increase by 1 i++; *pString++; } return rc; //free the memory free(rc); }

Um...memory leak there. Why are you allocating memory and returning it without it being freed? The free(rc) will never be called.

**made_of_asp** · Oct 9th, 2002, 08:21 AM

yeah the free() at the end is blocked...

the function that receives the string has to free the memory

**Cmdr0Sunburn** · Oct 9th, 2002, 05:48 PM

ohh man i was tired, i need a multipule one, many chars not just one, example replace "hjfassss","ss","03787u" somtin like that as an example. basicly like the one vb6 has, but vb6 one is 3x faster then my assembly one.

....
std::string::replace
Displaying Topics 1 to 1 of 1
only ref to std::string::replace is in this thread !!!!!

**parksie** · Oct 9th, 2002, 06:11 PM

I meant on Google, not the forums.

**Cmdr0Sunburn** · Oct 9th, 2002, 08:40 PM

ive searched google and are not many refrences to it. but when i do use it in c++ , i get

F:\C++\newprojects\strtest\strst.cpp(11) : error C2352: 'std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::replace' : illegal call of non-static member function
c:\program files\microsoft visual studio\vc98\include\xstring(295) : see declaration of 'replace'

**parksie** · Oct 10th, 2002, 04:46 AM

You have to call it *on* something...look at the function documentation.

**Cmdr0Sunburn** · Oct 10th, 2002, 03:19 PM

never mind about that, it isnt what i want, illl just have to use my assembly one. btw is c++'s __asm syntax masm? or tasm, nasm, fasm, spasm?????

**jim mcnamara** · Oct 10th, 2002, 04:29 PM

MASM32

**CornedBee** · Oct 11th, 2002, 06:10 AM

Post your assembly.

**Cmdr0Sunburn** · Oct 11th, 2002, 02:55 PM

ok...

loool too long, its 15000 chars, ill post atatchment

EDIT:

Code:

StringLen Proc  stdcall public,ptrSTRING1:DWORD;duh
push esi
mov esi,ptrSTRING1
xor eax,eax
cmp BYTE PTR [esi+eax],0
jne @F
pop esi
ret
@@:
inc eax
cmp BYTE PTR [esi+eax],0
jne @B
pop esi
ret
StringLen EndP

**CornedBee** · Oct 12th, 2002, 07:51 AM

Don't know anything about MASM special syntax. Are @@ and @F special jump marks?

So the PStrReplace is the main function?
I assume that lpReplace is the string to search for and PTRSTRING2REPW is the string with which it gets replaced, and PTRbuffer is the destination.

Given a call
PStrReplace("Hi there, er er er", "er", "ah", buffer);

buffer would then be
"Hi thahe, ah ah ah"
right?

Given all these conditions I wrote a C function and compiled it to assembly. It needs some optimizations, but I'm sure you're better at this.

Code:

INCLUDELIB LIBC
INCLUDELIB OLDNAMES

PUBLIC	_PStrReplace
EXTRN	_memcmp:NEAR
EXTRN	_strlen:NEAR
; Function compile flags: /Ods
;	COMDAT _PStrReplace
_TEXT	SEGMENT
_q$ = -12
_slen$ = -8
_p$ = -4
_szIn$ = 8
_szSearch$ = 12
_szReplace$ = 16
_buffer$ = 20
_PStrReplace PROC NEAR					; COMDAT
; File d:\download\forum\strreplace.c
; Line 5
	push	ebp
	mov	ebp, esp
	sub	esp, 12					; 0000000cH
; Line 6
	mov	eax, DWORD PTR _buffer$[ebp]
	mov	DWORD PTR _p$[ebp], eax
; Line 8
	push	DWORD PTR _szSearch$[ebp]
	call	_strlen
	pop	ecx
	mov	DWORD PTR _slen$[ebp], eax
$L1064:
; Line 9
	mov	eax, DWORD PTR _szIn$[ebp]
	movsx	eax, BYTE PTR [eax]
	test	eax, eax
	je	SHORT $L1065
; Line 11
	mov	ecx, DWORD PTR _szSearch$[ebp]
	movsx	ecx, BYTE PTR [ecx]
	cmp	eax, ecx
	jne	SHORT $L1066
; Line 14
	push	DWORD PTR _slen$[ebp]
	push	DWORD PTR _szSearch$[ebp]
	push	DWORD PTR _szIn$[ebp]
	call	_memcmp
	add	esp, 12					; 0000000cH
	test	eax, eax
	jne	SHORT $L1066
; Line 17
	mov	ebx, DWORD PTR _szReplace$[ebp]
	jmp	SHORT $L1068
$L1069:
	mov	eax, DWORD PTR _p$[ebp]
	mov	cl, BYTE PTR [ebx]
	mov	BYTE PTR [eax], cl
	inc	eax
	mov	DWORD PTR _p$[ebp], eax
	inc	ebx
$L1068:
	movsx	eax, BYTE PTR [eax]
	test	eax, eax
	je	SHORT $L1070
; Line 18
	jmp	SHORT $L1069
$L1070:
; Line 19
	mov	eax, DWORD PTR _szIn$[ebp]
	add	eax, DWORD PTR _slen$[ebp]
	mov	DWORD PTR _szIn$[ebp], eax
; Line 20
	jmp	SHORT $L1064
$L1066:
; Line 23
	mov	eax, DWORD PTR _p$[ebp]
	mov	ebx, DWORD PTR _szIn$[ebp]
	mov	cl, BYTE PTR [ebx]
	mov	BYTE PTR [eax], cl
	inc	eax
	mov	DWORD PTR _p$[ebp], eax
	inc	ebx
	mov	DWORD PTR _szIn$[ebp], ebx
; Line 24
	jmp	SHORT $L1064
$L1065:
; Line 25
	mov	eax, DWORD PTR _p$[ebp]
	and	BYTE PTR [eax], 0
; Line 26
	leave
	ret	0
_PStrReplace ENDP

Especially the lines 17 and 18 need optimizing, but the whole code contains quite a few redundant dereferencings. Sadly my version of VC++7 (Standard Edition) doesn't really optimize. Maybe keda can compile it and post it. I'll ask him.

Just in case you're interested, attached is the source file.

**CornedBee** · Oct 12th, 2002, 08:06 AM

And you should add a parameter that contains the max size of the buffer, and let the function check against overflow

**kedaman** · Oct 12th, 2002, 08:08 AM

Code:

; Listing generated by Microsoft (R) Optimizing Compiler Version 13.00.9466 

	TITLE	\Documents and Settings\Administrator\Desktop\strreplace.c
	.386P
include listing.inc
if @Version gt 510
.model FLAT
else
;	COMDAT ??_C@_02OEIPGGFF@ah?$AA@
CONST	SEGMENT DWORD USE32 PUBLIC 'CONST'
CONST	ENDS
;	COMDAT ??_C@_02FDKLDEFC@er?$AA@
CONST	SEGMENT DWORD USE32 PUBLIC 'CONST'
CONST	ENDS
;	COMDAT ??_C@_0BG@LKJNBNEP@Hello?5there?0?5er?5er?5er?$AA@
CONST	SEGMENT DWORD USE32 PUBLIC 'CONST'
CONST	ENDS
;	COMDAT ??_C@_03OFAPEBGM@?$CFs?6?$AA@
CONST	SEGMENT DWORD USE32 PUBLIC 'CONST'
CONST	ENDS
;	COMDAT _PStrReplace
_TEXT	SEGMENT PARA USE32 PUBLIC 'CODE'
_TEXT	ENDS
;	COMDAT _main
_TEXT	SEGMENT PARA USE32 PUBLIC 'CODE'
_TEXT	ENDS
FLAT	GROUP _DATA, CONST, _BSS
	ASSUME	CS: FLAT, DS: FLAT, SS: FLAT
endif

INCLUDELIB LIBC
INCLUDELIB OLDNAMES

PUBLIC	??_C@_02OEIPGGFF@ah?$AA@			; `string'
PUBLIC	??_C@_02FDKLDEFC@er?$AA@			; `string'
PUBLIC	??_C@_0BG@LKJNBNEP@Hello?5there?0?5er?5er?5er?$AA@ ; `string'
PUBLIC	??_C@_03OFAPEBGM@?$CFs?6?$AA@			; `string'
EXTRN	_printf:NEAR
;	COMDAT ??_C@_02OEIPGGFF@ah?$AA@
CONST	SEGMENT
??_C@_02OEIPGGFF@ah?$AA@ DB 'ah', 00H			; `string'
CONST	ENDS
;	COMDAT ??_C@_02FDKLDEFC@er?$AA@
CONST	SEGMENT
??_C@_02FDKLDEFC@er?$AA@ DB 'er', 00H			; `string'
CONST	ENDS
;	COMDAT ??_C@_0BG@LKJNBNEP@Hello?5there?0?5er?5er?5er?$AA@
CONST	SEGMENT
??_C@_0BG@LKJNBNEP@Hello?5there?0?5er?5er?5er?$AA@ DB 'Hello there, er er'
	DB	' er', 00H					; `string'
CONST	ENDS
;	COMDAT ??_C@_03OFAPEBGM@?$CFs?6?$AA@
CONST	SEGMENT
??_C@_03OFAPEBGM@?$CFs?6?$AA@ DB '%s', 0aH, 00H		; `string'
CONST	ENDS
PUBLIC	_PStrReplace
; Function compile flags: /Ogty
; File h:\documents and settings\administrator\desktop\strreplace.c
;	COMDAT _PStrReplace
_TEXT	SEGMENT
_slen$ = -4
_szSearch$ = 8
_szReplace$ = 12
_PStrReplace PROC NEAR					; COMDAT
; _szIn$ = eax
; _buffer$ = edx

; 5    : {

	push	ecx
	push	ebx
	push	esi
	push	edi
	mov	edi, DWORD PTR _szSearch$[esp+12]
	mov	ebx, eax

; 6    : 	char *p = buffer;
; 7    : 	const char *q;
; 8    : 	size_t slen = strlen(szSearch);

	mov	eax, edi
	lea	esi, DWORD PTR [eax+1]

; 26   : }

	npad	1

; 6    : 	char *p = buffer;
; 7    : 	const char *q;
; 8    : 	size_t slen = strlen(szSearch);

$L1155:
	mov	cl, BYTE PTR [eax]
	inc	eax
	test	cl, cl
	jne	SHORT $L1155
	sub	eax, esi
	mov	DWORD PTR _slen$[esp+16], eax

; 9    : 	while(*szIn)

	mov	al, BYTE PTR [ebx]
	test	al, al
	je	SHORT $L1157
	push	ebp
	jmp	SHORT $L1123
$L1159:
	mov	edi, DWORD PTR _szSearch$[esp+16]

; 26   : }

	npad	6
$L1123:

; 10   : 	{
; 11   : 		if(*szIn == *szSearch)

	cmp	al, BYTE PTR [edi]
	jne	SHORT $L1158

; 12   : 		{
; 13   : 			// scan ahead
; 14   : 			if(memcmp(szIn, szSearch, slen) == 0)

	mov	ecx, DWORD PTR _slen$[esp+20]
	mov	esi, ebx
	xor	ebp, ebp
	repe cmpsb
	jne	SHORT $L1158

; 15   : 			{
; 16   : 				// copy with incrementing p
; 17   : 				for(q=szReplace;*q;*p++ = *q++)

	mov	ecx, DWORD PTR _szReplace$[esp+16]
	mov	al, BYTE PTR [ecx]
	test	al, al
	je	SHORT $L1129

; 26   : }

	npad	6
$L1127:

; 15   : 			{
; 16   : 				// copy with incrementing p
; 17   : 				for(q=szReplace;*q;*p++ = *q++)

	mov	BYTE PTR [edx], al
	mov	al, BYTE PTR [ecx+1]
	inc	edx
	inc	ecx
	test	al, al
	jne	SHORT $L1127
$L1129:

; 18   : 					;
; 19   : 				szIn += slen;

	add	ebx, DWORD PTR _slen$[esp+20]

; 20   : 				continue;

	jmp	SHORT $L1154
$L1158:

; 21   : 			}
; 22   : 		}
; 23   : 		*p++ = *szIn++;

	mov	BYTE PTR [edx], al
	inc	edx
	inc	ebx
$L1154:
	mov	al, BYTE PTR [ebx]
	test	al, al
	jne	SHORT $L1159
	pop	ebp
$L1157:
	pop	edi
	pop	esi

; 24   : 	}
; 25   : 	*p = 0;

	mov	BYTE PTR [edx], 0
	pop	ebx

; 26   : }

	pop	ecx
	ret	0
_PStrReplace ENDP
_TEXT	ENDS
PUBLIC	_main
EXTRN	___security_cookie:DWORD
EXTRN	@__security_check_cookie@4:NEAR
; Function compile flags: /Ogty
;	COMDAT _main
_TEXT	SEGMENT
_buffer$ = -104
__$ArrayPad$ = -4
__$ReturnAddr$ = 4
_main	PROC NEAR					; COMDAT

; 29   : {

	sub	esp, 104				; 00000068H
	mov	eax, DWORD PTR ___security_cookie
	xor	eax, DWORD PTR __$ReturnAddr$[esp+100]

; 30   : 	char buffer[100];
; 31   : 	PStrReplace("Hello there, er er er", "er", "ah", buffer);

	push	OFFSET FLAT:??_C@_02OEIPGGFF@ah?$AA@
	mov	DWORD PTR __$ArrayPad$[esp+108], eax
	push	OFFSET FLAT:??_C@_02FDKLDEFC@er?$AA@
	lea	edx, DWORD PTR _buffer$[esp+112]
	mov	eax, OFFSET FLAT:??_C@_0BG@LKJNBNEP@Hello?5there?0?5er?5er?5er?$AA@
	call	_PStrReplace

; 32   : 	printf("%s\n", buffer);

	lea	eax, DWORD PTR _buffer$[esp+112]
	push	eax
	push	OFFSET FLAT:??_C@_03OFAPEBGM@?$CFs?6?$AA@
	call	_printf

; 33   : 	return 0;
; 34   : }

	mov	ecx, DWORD PTR __$ArrayPad$[esp+120]
	xor	eax, eax
	xor	ecx, DWORD PTR __$ReturnAddr$[esp+116]
	add	esp, 120				; 00000078H
	jmp	@__security_check_cookie@4
_main	ENDP
_TEXT	ENDS
END

**CornedBee** · Oct 12th, 2002, 08:15 AM

Thanks, keda, I knew VC++ could do better.

**Cmdr0Sunburn** · Oct 12th, 2002, 05:36 PM

wow thats remarcably small coding, but my code with out optimizations if 10x that.
btw
jmp @F will jump to the first ocurrence of @@:, forward, same for backwardz

**Cmdr0Sunburn** · Oct 12th, 2002, 06:09 PM

i use vb to test things. i estamate my 1.4ghz will spend 54,414,122 clock cycles(hz) give or take 1million
replacing 22,402 e's with 1's
and your c++ Function
1,451,930 clock cycles doing the same thing.
using QueryPerformanceCounter to time the vb function, and the rdtsc on the c++ one coded in.
wow 50x faster

thx all its exactly what i needed. but u can add a buffer overflow checker if you want. but i cant, it would lead to incompatablilties with my current programs.
just so you know, i have a lot of string functions to convert over to c++

**CornedBee** · Oct 13th, 2002, 10:45 AM

Tell me what they do, I'll try to find C solutions.

**CornedBee** · Oct 13th, 2002, 10:48 AM

Here's what the function would look like with checking:

Code:

void QStrReplace(const char *szIn, const char *szSearch,
				 const char *szReplace, char *buffer, size_t buflen)
{
	char *p = buffer;
	char *o = buffer+buflen-1;
	const char *q;
	size_t slen = strlen(szSearch);
	while(*szIn && p != q)
// from here like the other function

**Cmdr0Sunburn** · Oct 13th, 2002, 03:59 PM

Originally posted by CornedBee
Tell me what they do, I'll try to find C solutions.

lol most of them c++ already has, reson i made them is becuase assembly doesnt come with them. but here are a few that can be transed into c++

Code:

;---------------------------;---------------------------;---------------------------
;ascii to dword, eax is value;old stuff 
;---------------------------;---------------------------;---------------------------
a2dw Proc 	stdcall public Uses ecx edi edx esi, String:DWORD
      xor ecx, ecx
      mov edi, String
      Invoke StringLen, edi
      .While eax != 0
        xor edx, edx
        mov dl, byte ptr [edi]
        sub dl, "0" ; subtrack each digit with "0" to convert it to hex value
        mov esi, eax
        dec esi
        push eax
        mov eax, edx
        push ebx
        mov ebx, 10
          .While esi > 0
            mul ebx
            dec esi
          .EndW
        pop ebx
        add ecx, eax
        pop eax
        inc edi
        dec eax
      .EndW
        mov eax, ecx
        ret
a2dw EndP

Code:

;---------------------------;---------------------------;---------------------------
;Crc Table from Thomas
;---------------------------;---------------------------;---------------------------
Thomas1crctable proc uses ebx esi edi
cmp CrcAlreadyFilled,1
je @Thomas1crctableEND

	mov		edi, offset CRCtable  - 4
	xor		ecx, ecx
	
	_ml:
	mov		eax, ecx
	;mov		ebx, 0EDB88320h
	add		edi, 4
	mov		esi, 8
	@@:
		shr eax, 1    
		sbb edx, edx  
		and edx, 0EDB88320h
		xor eax, edx
	dec	esi
	jnz	@B
	inc		ecx
	mov		[edi], eax
	cmp		ecx, 256
	jb		_ml
    mov CrcAlreadyFilled,1
    @Thomas1crctableEND:
ret
Thomas1crctable endp
;---------------------------;---------------------------;---------------------------
;Crc algo from Thomas
;---------------------------;---------------------------;---------------------------
Thomas2CrC proc uses ebx esi edi buf:DWORD, len:DWORD
cmp CrcAlreadyFilled,1
je @F
call Thomas1crctable
@@:
	mov		esi, buf
	mov		edi, offset CRCtable
	mov		edx, len
	shr		edx, 1
	or		ecx, -1
	xor		eax, eax
	@@:
	mov		al, [esi]
	xor		al, cl
	shr		ecx, 8
	mov		ebx, [edi+4*eax]
	xor		ecx, ebx
	mov		al, [esi+1]
	xor		al, cl
	shr		ecx, 8
	mov		ebx, [edi+4*eax]
	add		esi,2
	xor		ecx, ebx
	dec		edx
	jnz		@B

	test	len, 1
	jz		@F
	mov		al, [esi]
	xor		al, cl
	inc		esi
	shr		ecx, 8
	mov		ebx, [edi+4*eax]
	xor		ecx, ebx
	@@:

	mov		eax, ecx   
	not		eax
    ret
    
Thomas2CrC endp

Code:

;---------------------------;---------------------------;---------------------------
; gets an error discription from number
;---------------------------;---------------------------;---------------------------
GetErrDescriptionP Proc Uses ebx edi ErrNum:DWORD
    Local hLocal:DWORD
    ;LOCAL Buffer1[256]:BYTE
    mov eax,ErrNum
    or eax,eax
    jne WeAlreadyKnowIt
    Invoke GetLastError
    WeAlreadyKnowIt:
    mov edi,eax
    Invoke FormatMessage,FORMAT_MESSAGE_ALLOCATE_BUFFER or \
                         FORMAT_MESSAGE_FROM_SYSTEM,
                         0,             ; GetItFromSystem
                         edi,0,         ; ErrNum,Default language
                         Addr hLocal,   ; where to send the address of string from system
                         0,0            ; any size, no arguments
    or eax,eax
    mov ebx,Offset UnKnown
    je UnKnown
    Invoke LocalLock,hLocal
    mov ebx,eax
    UnKnown:
    Invoke wsprintf,Addr Buffer1,Offset ErrMsgTmpl,edi,ebx
    Invoke MessageBox,0 ,Addr Buffer1,Addr mberr1,MB_OK + MB_ICONINFORMATION + MB_TOPMOST
    cmp ebx,Offset UnKnown
    je @F
    Invoke LocalFree,hLocal
  @@:
Invoke gggge,Addr Buffer1
    ret
GetErrDescriptionP EndP
;---------------------------;---------------------------;---------------------------
;end
;---------------------------;---------------------------;---------------------------

**parksie** · Oct 13th, 2002, 04:11 PM

I can see the relevance of these if you're programming in asm, or if you're in C and want something highly optimised.

Using them in C++ is just asking for trouble, though, and most things are already provided in forms which will usually be fast enough.

**Cmdr0Sunburn** · Oct 13th, 2002, 04:13 PM

i just want those for, compatability, im converting a asm dll into c++, so i can add a whole lot to it using c++!

**CornedBee** · Oct 14th, 2002, 04:39 AM

atoi is nearly the same as the a2dw function.

Those functions seem efficient enough, but I don't know what the crc functions should do.

**Cmdr0Sunburn** · Oct 14th, 2002, 03:26 PM

you should know whata crc does........ it creates a unique number for a array of bytes.

**parksie** · Oct 14th, 2002, 08:03 PM

Cyclic Redundancy Check...

Frequently used as error-correction, but not 100% reliable. Pretty good though. Boost has C++ code to do this...

**CornedBee** · Oct 15th, 2002, 04:21 AM

Never heard of it.
Can you explain concepts and usage to me?

**parksie** · Oct 15th, 2002, 08:43 AM

http://www.geocities.com/SiliconVall...s/8659/crc.htm

**CornedBee** · Oct 15th, 2002, 09:39 AM

Thanks.

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