topic Re: What does * mean in C programming? in CodeWarrior for MCU

What does * mean in C programming?

admin — Thu, 26 Feb 2009 14:42:53 GMT

Hi. Below is a code to write characters to a LCD display. I would like to know what does the * mean. Thx

void lcd_string(byte line,byte *_data_buffer)
{
     byte i;
     __RESET_WATCHDOG();
    if(line==1)
      {
        lcd_write_cmd(0x40); //DDRAM
        Check_LCD_Busy();//
        lcd_write_cmd(0x80); //CGRAM
        Check_LCD_Busy();
      }
      else
      {
        //lcd_write_cmd(0); //DDRAM
        lcd_write_cmd(60); //DDRAM
        Check_LCD_Busy();//

        lcd_write_cmd(0xc0); //CGRAM
        Check_LCD_Busy();//while((lcd_read_cmd()&0x80)==0x80);
      }

  for(i=0;i<LCD_16X2;i++)
  {
    if(_data_buffer[i]!=0)
    {
      lcd_write_data(_data_buffer[i]);
      Check_LCD_Busy();
    } else break;
  }
}

Message Edited by Cryptical on 2009-02-26 06:44 AM

Re: What does * mean in C programming?

PEBeginnerBeh — Thu, 26 Feb 2009 17:12:30 GMT

I think byte *_data_buffer defines a pointer wich has the range of a byte. * mean that the follow variable is define or use (for use it must be define befor) as a pointer.

Example:

char *test defines a pointer test with a rang from 0 to 255.

Message Edited by PEBeginner on 2009-02-26 09:25 AM

Re: What does * mean in C programming?

admin — Thu, 26 Feb 2009 17:39:30 GMT

Thx for the reply. So i think the program above means writing a character to the first space of the LCD, and then points to the next space and repeats the process.

Re: What does * mean in C programming?

bigmac — Thu, 26 Feb 2009 17:48:52 GMT

Hello,

The following is an example of using the function -

const byte str1[] = "The quick brown fox";

const byte str2[] = ...

...

void main(void)

{

...

lcd_string(1, str1);

The value of str1 is a pointer to the first element (character) of the array str1[].

Regards,

Mac

Re: What does * mean in C programming?

PEBeginnerBeh — Thu, 26 Feb 2009 17:50:43 GMT

Yes, so the programm works.