Weird multiplication

[Karl]

Hi,

I have a simple routine to get a 4 digit(up to) number from the keypad, I then try to return this value as an int16. When I try to display the returned value on the screen I get weird values - eg when i type in 9876, the lcd displays 9102 (I think). Here is the code:

unsigned int16 KEYPAD_GetVal(void)
{
unsigned int8 i8_len = 0;
unsigned int8 i16_keyarr[6];
unsigned int8 i8_end = FALSE;
unsigned int16 i16_returnvalue;

while (i8_end == FALSE)
{
i16_keyarr[i8_len] = KEYPAD_GetKeyPress(); // KEYPAD_GetKeyPress() returns int8

if ( ((i16_keyarr[i8_len]) < 10) && (i8_len < 5))
{
lcd_putc(i16_keyarr[i8_len] + 0x30);
i8_len++;
}
else if (i16_keyarr[i8_len] == KEY_STOP)
{
if (i8_len == 0) { i8_end = TRUE; }
else {lcd_putc('\b'); lcd_putc(' '); lcd_putc('\b'); i8_len--; putc(0x02);putc(0x6A);putc(0X03);}
}
else if (i16_keyarr[i8_len] == KEY_ACCEPT)
{
if (i8_len != 0) { i8_end = TRUE; }
}

}

if (i8_len == 0) i16_returnvalue = (int16)(0);
if (i8_len == 1) i16_returnvalue = (int16)(i16_keyarr[0]);
if (i8_len == 2) i16_returnvalue = (int16)((i16_keyarr[0]*10) + i16_keyarr[1]);
if (i8_len == 3) i16_returnvalue = (int16)((i16_keyarr[0]*100)+(i16_keyarr[1]*10) + i16_keyarr[2]);
if (i8_len == 4) i16_returnvalue = (int16)((i16_keyarr[0]*1000)+(i16_keyarr[1]*100)+(i16_keyarr[2]*10) + i16_keyarr[3]);

return i16_returnvalue;

}

static unsigned char uc_buf[8];
printf(lcd_putc,"\f %s ",itoa(i16_returnvalue,10,uc_buf));

Is the problem I am trying to multiply 8 bit ints together to give a 16bit int?

Any help greatly appreciated!!
Thanks,
Karl

[PCM programmer]

CCS has a function that will do the conversion from ascii decimal to
an unsigned integer. It's called atol. All you have to do is pass it
a string of digits. Just make sure there's a string-terminator byte
of 0x00 at the end of the digits (however many there are), and make
sure the array is large enough to hold the digits and the terminator.

Here's a demo program for atol(). It displays the following output:

[Karl]

Hi PCM programmer,

Thanks for your reply, that is a much easier way of doing it thanks.

Karl