*String to String[] to *String

This is a discussion on *String to String[] to *String within the C Programming forums, part of the General Programming Boards category; how can I copy a string like *String to a string like String[] ? and vice-versa? thanks!...

  1. #1
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    Question *String to String[] to *String

    how can I copy a string like *String to a string like String[]? and vice-versa?

    thanks!

  2. #2
    and the hat of int overfl Salem's Avatar
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    strcpy
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  3. #3
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    *String ---> String[]

    Code:
    #include<stdio.h>
    #include<string.h>
    
    main(void)
    {
       char *String1 = "Program";
       int len = strlen(String1);
       
       char String2[len];
       
       strcpy(String2,String1);
       
       printf("%s = %s", String1,String2);
       
       getchar();
       return(0);
             
    }
    String[] ---> *String

    Code:
    #include<stdio.h>
    #include<string.h>
    
    main(void)
    {
       char String1[] = "Program";
       
       char *String2;  
       
       strcpy(String2,String1);
       
       printf("%s = %s", String1,String2);
       
       getchar();
       return(0);
             
    }

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    thanks... but I have a little problem here.

    I will only know the *String after few lines of code... so I can't know the lenght of this when I declare the strings... is possible to change the size after declare? so how can I do that?

    thanks again!

  5. #5
    Registered User ssharish2005's Avatar
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    So use dynamic memory allocation method. Once you know the length of the array do

    Code:
    char *str;
    
    str = malloc( sizeof char * len+1);
    FYI: If you still need increase the size use realloc function . I case if you wanted to increase the size in the future.

    EDIT: You need one more byte for null as well.
    ssharish2005
    Last edited by ssharish2005; 06-18-2007 at 05:34 AM.

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    don't forget to check for failure and to free it when you're done.

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    Question

    but this is a pointer right?

    I'm like this:

    Code:
    char *String;
    char NewStr[];
    
    
    do some lines of code than I get *String;
    
    len = strlen(String);
    
    NewStr[] = malloc( sizeof char * len); // can I do that?
    well, I need to read/copy char by char of this string to another, but seams that I can't do it like this:

    Code:
    char *String; //I can't change this!
    char *NewStr;
    		   while (String[j] != '}'){ 
    			   NewStr[i] = String[j];
    			   i++;j++;
    		   }
    so I think if *NewStr was a NewStr[] will work... or am I wrong?

    thanks again!

  8. #8
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    NewStr[] is an array with an undetermined number of elements. It won't take a value returned from malloc. You'll need a pointer for that.

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    Question

    hmmm... so how I get the same result as the loop below using pointers?

    Code:
    char *String; 
    char *NewStr;
    		   while (String[j] != '}'){ 
    			   NewStr[i] = String[j];
    			   i++;j++;
    		   }
    thanks again!

  10. #10
    CSharpener vart's Avatar
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    but you stilll need a malloc
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  12. #12
    Woof, woof! zacs7's Avatar
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    Your also not allocating enough room for the null terminator

  13. #13
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    ok, I need do a malloc... but about my loop? is right?

    is just because I do not alloc/free mem that didn't work? or what I did isn't possible to do with pointers like I did? or BOTH???

    thanks again!

  14. #14
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    Question I can't even copy the string...

    remove everything, then I'm trying part by part... but I'm stuck in the first one.

    any of what you post worked.

    Code:
    /*
     =================
     CM_LoadEntityString
     =================
    */
    static void CM_LoadEntityString (const byte *data, const lump_t *l){
    
    	char	*game = Cvar_VariableString("fs_game"); // declare game - Hajas
    	FILE	*f, *g;
    	int		i, j, Tam, TamNew;
    	int		PA, PB, PC, PD, PL, Num, Espaco, Aspas;
    	char	*p = NULL, *ori = NULL, *HStr = NULL, *NewStr = NULL, *FinalStr = NULL;
    	char	*PartA = NULL, *PartB = NULL, *PartC = NULL, *PartD = NULL;
    
    
    	cm_numEntityChars = l->fileLen;
    	if (cm_numEntityChars < 1)
    		return;
    	if (cm_numEntityChars > MAX_MAP_ENTSTRING)
    		Com_Error(ERR_DROP, "CM_LoadMap: map '%s' has too large entity lump", cm_map);
    
    	cm_entityString = Hunk_Alloc(cm_numEntityChars + 1);
    	memcpy(cm_entityString, data + l->fileOfs, cm_numEntityChars);
    
    	f = fopen ("entityORI.cfg", "wb");
    	fprintf(f, "%s\n", cm_entityString);
    	fclose(f);
    
    	//if (!Q_stricmp(game, "arena")){
    		// do string manipulation over cm_entityString
    		*NewStr = 0;
    		*FinalStr = 0;
    		Tam = strlen(cm_entityString);
    		HStr = malloc(sizeof cm_entityString);
    		strcpy(HStr, cm_entityString); // copy the original string to mine
       
    	g = fopen ("entityALT.cfg", "wb");
    	fprintf(g, "%s\n", HStr);
    	fclose(g);
    	free(HStr);
    	//}
    }
    abort the game....

    I tryed these lines too:

    Code:
    HStr = malloc(sizeof (cm_entityString));
    HStr = malloc(sizeof char * cm_entityString);
    HStr = malloc(Tam);
    HStr  = Hunk_Alloc(sizeof(cm_entityString));
    nothing works... I'm doing nothing aside copy the string, why is not working?

  15. #15
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    Code:
    ptr = malloc(sizeof(type) * elements);

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