mysterious overwriting of memory

This is a discussion on mysterious overwriting of memory within the C++ Programming forums, part of the General Programming Boards category; I'm making this text demo for the GBA. Anways I'm making this function to convert ASCII character to my characters. ...

  1. #1
    Registered User Mr_Jack's Avatar
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    Unhappy mysterious overwriting of memory

    I'm making this text demo for the GBA. Anways I'm making this function to convert ASCII character to my characters. For some reason when I try to generate a string using this function all of my image data gets overwritten. Well, here is the code for that function:
    Code:
    u16 * ascii_to_mine(const char * str, const u8 len)
    {
    	u16 * mstr = new u16[len];
    	
    	u16 loop;
    	for (loop = 0; loop < len; loop++)
    		mstr[loop] = (u16)(str[loop] - 32);
    }
    u16 and u8 are just typdefs for unsigned short and unsigned char. Is there anything here that is kinda funny? I know the problem isn't my method of writing the data since I converted some strings manually and everything went just fine. Thanks for your help!

  2. #2
    vae victus! skorman00's Avatar
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    Code:
    mstr[loop] = (u16)(str[loop] - 32);

    What exactly are you trying to do with this line? I don't see how this is converting the old text to your characters. Unless you some how defined your characters to be 32 less than the normal ASCII characters, you're just changing them to other ASCII characters.

    IE: 'A' would become '7'

  3. #3
    Registered User Mr_Jack's Avatar
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    No, this is excactly what I need to do. My program uses all ASCII characters 32-100 and something. My program has the images of each characters stored in special places in the GBAs memory and I need to use the numbers 0-something to access the images and make them draw onscreen. I'm not sure if I explained that well, but that is excactly what I mean to do.

  4. #4
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    Code:
    u16 * ascii_to_mine(const char * str, const u8 len)
    {
    	u16 * mstr = new u16[len];
    	
    	u16 loop;
    	for (loop = 0; loop < len; loop++)
    		mstr[loop] = (u16)(str[loop] - 32);
    }
    Well, you're not returning anything, so you're doing a lot of work for nothing. So add a return at the end.
    Code:
    u16 * ascii_to_mine(const char * str, const u8 len)
    {
    	u16 * mstr = new u16[len];
    	
    	u16 loop;
    	for (loop = 0; loop < len; loop++)
    		mstr[loop] = (u16)(str[loop] - 32);
    	return mstr;
    }
    And I'm assuming you use len to determine the end of your new string. Otherwise you'd need an extra slot for a terminator.

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