simple C question

[Colt45]

I can't seem to think of how to do this, but there must be a simple way.

I've got an ADC coming in, dumping the value into a char.. so 0...255.

I need to take the value and split each decimal digit into its own char.

eg.
adc in = 123

char A = 1
char B = 2
char C = 3

I can't seem to think of an easy way to do it though?

 

[SoundTheSurrender]

How about a (str + 0), (str + 1) etc.. and throw it into it's own char?

I think you have to use pointers.

 

[Colt45]

I came up with this abortion.. seems to work.. not exactly pretty though

char_A = ADC_IN;
char_B = ADC_IN;
char_C = ADC_IN;
char_A /= 100;
char_B -= char_A * 100;
char_B /= 10;
char_C -= char_A * 100;
char_C -= char_B * 10;
char_C /= 1;

 

[SoundTheSurrender]

Well as long as it works..
I actually don't use C, only been using C++ so I don't know.

Here's a idea.

char str[80] = "235";
(str) or (str + 0) points to the '2'
(str + 1) points to 1st '3'
(str + 2) points to 2nd '5'

Then you could throw it into a variable.

This is how I'd do it in C++, I think it would be similar in C..

 

[Net]

Okay, hopefully I didn't ready the post wrong.

here ya go:

#include <stdio.h>

int main(){

int num = 123, i, index = 3;
int num_chop[index];

for (i = (index-1); num != 0; i--){
num_chop = num%10;
num /= 10;
}

for (i = 0; i < index; i++){
printf ("\nnum_chop[%d]= %d", i, num_chop );
}

return 0;
}

 

[Net]

num is the value to seperate into digits.
so num = 123;

printout looks like this

num_chop[0] = 1
num_chop[1] = 2
num_chop[2] = 3

 

[HigherGround]

here's how I'd do it. the whole approach really boils down to a sprintf(...) call. the rest of the code just shows you a way to dynamically find string length for any integral value.

 

[SoundTheSurrender]

Well he said that the values are in char form...

 

[HigherGround]

Originally posted by: SoundTheSurrender
Well he said that the values are in char form...

chars, ints, longs, what's the difference?

 

[Net]

Colt45 what is the program for (ie intent or purpose).
there might be an even simpler approach.

 

[Aikouka]

I'm not sure how exactly you're getting the input, but if it's from user input, you could just use:

scanf("%c%c%c", &a, &b, &c);

where a, b and c are defined as characters.

If you get it as an integer already entered, just do:

my_int = 123;
a = (my_int / 100) + 48;
b = ((my_int / 10) % 10) + 48;
c = (my_int % 10) + 48;

You mentioned something similar to this above, but it shouldn't work correctly, because a single-digit integer's value is not the same as its character representation. They're 48 off, which is why I added 48 to the characters in the value above. You can also simply add '0' (the character zero).

 

[Colt45]

Its for a PIC microcontroller.

the compiler has a built in "adc_get" sort of routine. I pull the data from that,
then I split the value into the 3 pieces, read them off an array to change them to a 7-segment value instead of binary, and send them to 3 multiplexed 7 segment displays.

I'm using a pressure sensor from one of my car ECUs that blew up. So it will be a sort of atmospheric pressure / boost / vacuum gauge.


I guess I should have made it more clear originally. The code i've got now seems to function, but I managed to blow up the micro I originally wrote it for, so now i need to rebuild the circuit to use one with a different pinout :|
I knew using brown as +5v was going to come back to haunt me. hehe.

 

[Yomicron]

I would stick with the code you already have. The only change I would make would be to remove the divide by 1 at the end. It doesn't do anything other than waste CPU cycles.

 

[Net]

ah, reminds me of a electrical engineering class I had were we programed a 7 segment display on a fpga board. it was creating a stop watch.