String problem - GameCreators Forum

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wh1sp3r

21

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Joined: 28th Sep 2003

Location: Czech republic

Posted: 27th Jan 2008 21:36 Edited at: 27th Jan 2008 22:46

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hello,

I have problem with that code

+ Code Snippet

    char file[256];
    char file_data[256];
   

void DarkGDK ( void )
{

   
	dbPrint("Zadejte nazev souboru ");
	strcpy(file, dbInput()); 
    
   
	dbOpenToRead(1, file);

	while(!strcmp(file_data,"[SOURCES]") == 0)
	{
    char* file_data = dbReadString( 1 );
	
	dbPrint(file_data);
    dbPrint(dbStr(strcmp(file_data,"[SOURCES]")));
	
	dbWaitKey();
	//if(strcmp(file_data,"[SOURCES]")==0) dbPrint("JOOOOO");
	} 
	
	dbWaitKey();
}

While is still looping

When it found "[SOURCES]" ..strcmp(file_data,"[SOURCES]") this function return 0. I dont know WHY ! When the condition is FALSE, It dont want to jump away from while loop

if you uncomment "if(strcmp(file_data,"[SOURCES]")==0) dbPrint("JOOOOO");
" Its show JOOOO, when "SOURCES" found.

PS: Real programmers aren't afraid of math!.

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Morcilla

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Joined: 1st Dec 2002

Location: Spain

Posted: 28th Jan 2008 15:48

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Try to declare (and feed with the initial value)

+ Code Snippet

char* file_data

before the while loop...

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wh1sp3r

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Location: Czech republic

Posted: 28th Jan 2008 16:28 Edited at: 28th Jan 2008 16:31

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Morcilla: It doesnt work

PS: Real programmers aren't afraid of math!.

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Morcilla

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Location: Spain

Posted: 28th Jan 2008 16:41 Edited at: 28th Jan 2008 16:45

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Sure, that was because the variables defined inside an 'if', or inside any loop, are local variables, and can only be 'seen' inside that loop or if.

I see you have defined

+ Code Snippet

char file_data[256]

at the beginning of the code. Now this variable is a global one, and can be used anywhere.

But later you wrote:

+ Code Snippet

while(!strcmp(file_data,"[SOURCES]") == 0)
	{
    char* file_data = dbReadString( 1 );
...

That 'char* file_data' defines a new variable, with the same name than the global one. Bad practice in any case.
I guess you wanted to say:

+ Code Snippet

file_data = dbReadString( 1 );

to keep on using the global variable. Otherwise, inside the loop, the local one is the one used, and the 'while' is probably checking the global one.

One C/C++ basics is that when using arrays, the name of the array holds the pointer to the array, that is, in this case 'file_data' is already a pointer of type 'char*'.

[Edit: Lol, you shouldn't edit your posts that way, now where stands what I said, lol]

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wh1sp3r

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Posted: 28th Jan 2008 16:56

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Morcilla: Hehe

Thank you for explanation. I'll try

PS: Real programmers aren't afraid of math!.

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wh1sp3r

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Posted: 28th Jan 2008 17:02 Edited at: 28th Jan 2008 17:20

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Still problem:

+ Code Snippet

    char file[256];
    char file_data[256];
   

void DarkGDK ( void )
{
    int promenna;
    promenna = 1;
	dbPrint("Zadejte nazev souboru ");
	strcpy(file, dbInput()); 
    
   
	dbOpenToRead(1, file);

	while(!(0==strcmp((char*) file_data,"[SOURCES]")))
	{
    file_data = dbReadString( 1 );
	dbWaitKey();

	dbPrint(file_data);
	} 
	dbPrint("hotovo");
	dbWaitKey();
}

ERROR:

+ Code Snippet

1>.Main.cpp(43) : error C2440: '=' : cannot convert from 'char *' to 'char [256]'

Problem is Here

"file_data = dbReadString( 1 );"

EDIT:

This works:

+ Code Snippet

    char file[256];
    char file_data;
    char* p_file_data;

void DarkGDK ( void )
{
    p_file_data = &file_data;
	int promenna;
    promenna = 1;
	dbPrint("Zadejte nazev souboru ");
	strcpy(file, dbInput()); 
    
   
	dbOpenToRead(1, file);

	while(!(0==strcmp(p_file_data,"[SOURCES]")))
	{
    p_file_data = dbReadString( 1 );
	dbWaitKey();

	dbPrint(p_file_data);
	} 
	dbPrint("hotovo");
	dbWaitKey();
}

PS: Real programmers aren't afraid of math!.

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Morcilla

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Joined: 1st Dec 2002

Location: Spain

Posted: 29th Jan 2008 10:21

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Well, I haven't used dbReadString before, so I really don't know if it reads a single char or a whole string uh.
I guess you're going to find out before I do.
What does return

+ Code Snippet

dbPrint(p_file_data);

then?
I guess the aim is to read a file until the reading reaches the "[SOURCES]" string...
At least now you have the variables properly declared.

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Dark GDK / String problem