strcopy for an array

This is a discussion on strcopy for an array within the C++ Programming forums, part of the General Programming Boards category; suppose i have an array of size 12, and i wanted to strcpy() it into a c-style string. any "quick" ...

  1. #1
    i want wookie cookies the Wookie's Avatar
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    strcopy for an array

    suppose i have an array of size 12, and i wanted to strcpy() it into a c-style string. any "quick" way of doing this? its complaining about casting and wrong types..its starting to annoy me. then i got past some of the problems...and then it gaved casting problems, like to a constant, i tried const_cast<> but no luck..

    ex:

    char array[12];
    char *newstring;
    strcpy(newstring, &array);

    something like that...

  2. #2
    Code Goddess Prelude's Avatar
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    >char *newstring;
    >strcpy(newstring, &array);
    And where were you planning on putting these 12 characters in a freshly declared local pointer? Provided you allocate memory to newstring and provided array actually ends with a nul character
    Code:
    strcpy ( newstring, array );
    should work okay for you.
    Last edited by Prelude; 11-03-2003 at 08:06 PM.
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  3. #3
    i want wookie cookies the Wookie's Avatar
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    it keeps saying

    c:\Documents and Settings\Nabeel.Shahzad\My Documents\Visual Studio Projects\temp_mon\daemon\cmbm.cpp(103): error C2664: 'strcpy' : cannot convert parameter 2 from 'unsigned char [12]' to 'const char *'

  4. #4
    mustang benny bennyandthejets's Avatar
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    Post the actual code you're using. I suspect you're not using the correct syntax. A static array variable without square braces should resolve to an LPCHAR, and the error you received implies that you wrote:
    Code:
    strcpy(newstring,array[]);
    //or
    strcpy(newstring,array[12]);
    It should be:
    Code:
    lstrcpy(newstring,array);
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  5. #5
    and the hat of wrongness Salem's Avatar
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    > cannot convert parameter 2 from 'unsigned char [12]' to 'const char *'
    You're still doing &array (as per your original example)
    Lose the &
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  6. #6
    Registered User major_small's Avatar
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    just wondering... for the example he gave, would this work:
    Code:
    ...
    char array[12];
    char*newstring=new char[strlen(array)];
    int i;
    
    for(i=;i<strlen(newstring);i++)
         newstring[i]=array[i];
    
    newstring[i]='\0';
    ...
    I'm not asking if it's efficient, just if it would work...
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  7. #7
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    first thing, i guess u must initialise array, second thing, array length != 0

    third in the loop u can't use strlen(newstring), it must be strlen(array).

    newstring hasn't been terminated by the program so the length of newstring could be anything.

  8. #8
    Registered User major_small's Avatar
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    thanks... I don't feel much like thinking now, so can you please remind me if that last line is right, or should it be:
    Code:
    newstring[i+1]='\0';
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  9. #9
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    no the way u've done it, it should be newstring[i] = '\0';

    but personally this is the way i would do it.

    since '\0' character value is 0, the loop will end with that value.

    Code:
    for(i = 0; array[i]; ++i)
        newstring[i] = array[i]
    
    newstring[i] = '\0';
    actually i missed something in ur code above, it shouldn't be

    Code:
    char *newstring = new char[strlen(array)];
    it should be

    Code:
    char *newstring = new char[strlen(array)+1];
    requires the +1 for the '\0' terminator
    Last edited by Kyro; 11-04-2003 at 07:16 AM.

  10. #10
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    let my try majors idea


    here is my code
    Code:
    struct ... {
    unsigned char ssName[12];             // name of sensor
    }
    
    .....
    strcpy(name, data->sdSensor[n_sensor].ssName);

    edit:
    Code:
    char *retval = new char[13];
    		for(int i=0;i<13;i++){
    			retval[i]=data->sdSensor[n_sensor].ssName[i];
    		}
    		retval[12]='\n';
    this worked..but i dont like the loop thing. and strlen() didnt work on the array, but luckily i know the array's size anyway



    oh, and i dont know if the string arrays are null terminated or not, i assume they are...the values are being read through OpenFileMapping
    Last edited by the Wookie; 11-04-2003 at 08:02 AM.

  11. #11
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    first one, u can't convert unsigned char[] to char*

    in other words u can't have

    Code:
    char *pc = 'l';
    unsigned char *upc = pc;
    u'll get a compiler error without a type cast.

    the second one looks fine. what was wrong with strlen? if u pass data->sdSensor[n_sensor].ssName to it, it should work.

  12. #12
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    yeah, it should..but it doesnt. im trying something else

  13. #13
    Registered User major_small's Avatar
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    Originally posted by Kyro
    it should be

    Code:
    char *newstring = new char[strlen(array)+1];
    requires the +1 for the '\0' terminator
    yeah, i just forgot the +1 in there... thanks though...
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  14. #14
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    oh gee, i'm half asleep, it doesnt work on the array because data->sdSensor[n_sensor].ssName is type unsigned char[]. U can't pass an unsigned char[] or unsigned char* to strlen. sorry about that.

    i think i'll go to sleep now :S

  15. #15
    Registered User major_small's Avatar
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    is there an easy way to change the type of a string besides looping through each element and casting it to another string of a different data type?
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