Significance of * (star) in this program

[Manu]

void lcd_disp(unsigned char C)
{
LCD=C;
LCD_RS=1;
LCD_EN=1;
delay_ms(1);
LCD_EN=0;
}
void lcd_data(unsigned char *disp)
{
while(*disp)
lcd_disp(*disp++);
}

This is a C program to display strings on LCD. I am not able to understand the significance of *(star) in this program. Please any one give the answer.

[shailesh]

First of all you need a basic knowledge of C lang….

by the way it is not star but is is called as a POINTER…..

 

 

void lcd_data(unsigned char *disp)

{

while(*disp)

  lcd_disp(*disp++);

}

 

 

explanation..

 

 while(*disp) is conditional statament if Your character is not null ( ‘’ ) then and then lcd_disp(*disp++); executed and then due to Post increment Next address is came in pointer…and again while(*disp) condition check if it not null then display on lcd otherwise condition of loop is false and loop is terminated…

 

 

So Pointer is gives You a address Of your Variables…

Like wise

Disp[8]=”SHAILESH” stored at 0x00H then

 

*Disp will giive your a Address Of Disp[0] Not ‘S’;

 

 

 

 

[AJISH ALFRED]

Hi Ganesh,

Next time when you post the code, please don’t forget to format it in the proper way as I’ve done for you this time.

 

void lcd_disp(unsigned char C) 

{

      LCD=C; LCD_RS=1; LCD_EN=1;

      delay_ms(1);

      LCD_EN=0; 

}

 

void lcd_data(unsigned char *disp) 

{ 

     while(*disp) 

            lcd_disp(*disp++); 

}

 

The *disp is a pointer to an array that holds the character to be displayed. Initially it will point to the first charcter of the array and as you increase the pointer like (*disp++) it point to the succeeding characters.

 

Is this code working?

 

If you have any doubts, please feel free to post here.

[Author]

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