Electricity monitor - need some help

[GeekDoc 226]

Chugging along now, but hit a snag. Does anyone have a good routine to turn an unsigned int into its string equivalent (to send to LCD)? This routine throws errors in completely unrelated functions when I add it (commenting it out builds clean) :?

 

/* Takes an int and returns a char[5]
* a 16-bit unsigned int can be a max of 5 characters (65535)
*/ 
char[] int_to_str(unsigned int i)
{
char[5] the_str;
int str_pos = 0;

//parse into char[]
for(str_pos = 0; str_pos < 4; str_pos++)
{
	the_str[str_pos] = i / (10^(4 - str_pos));
	i -= i / (10^(4 - str_pos));
}

return the_str;
}

[zeke 693]

I use sprintf() to do this.

 

Here's an example that I ripped off the net somewhere:

 

#include 
// ^ must include to use sprintf()
// we will start with a simple integer ex.
int main()
{
  char buff[50];
  int ret, a = 34, b = 234;

  ret = sprintf(buff, "%d minus %d equals %d",a,b,a-;

  printf ("(%s) is the result of our sprintf, which is %d characters long",buff,ret);

  return 0;
}

 

Instead of a real string, you could just put your number in there somewhere like this:

 

ret = sprintf( buff, "%d", youruint);

 

Does that help?

[zeke 693]

I just noticed that in the ctype.h library, there is a function called toascii().

 

See if that might help you.

[zeke 693]

Yeah, in the ctype.h file you should find this macro:

 

#define _toascii(a)  ((a) & 0x7F)

 

That should convert an integer to ASCII.

 

Helpful?

[cde 334]

I think Geekdoc needs something that turns the number "234" into the string "234", instead of number "234" into ascii char 234 which is "

[RobG 1,892]

How about something like this:

//assume data is an array of your chars and myInt is the int you want to convert
//0x30 is where numbers start in ASCII
unsinged int charPos = 0;
while(myInt > 0) {           
data[charPos] = 0x30 + (myInt % 10);  
myInt /= 10;
charPos++;
}

[GeekDoc 226]

I think Geekdoc needs something that turns the number "234" into the string "234", instead of number "234" into ascii char 234 which is "

[GeekDoc 226]

How about something like this:

//assume data is an array of your chars and myInt is the int you want to convert
//0x30 is where numbers start in ASCII
unsinged int charPos = 0;
while(myInt > 0) {           
data[charPos] = 0x30 + (myInt % 10);  
myInt /= 10;
charPos++;
}

I started that way, but it will reverse the digits:

 

2345 % 10 = 5

234 % 10 = 4

...

 

Going to check through libraries. This is a commonly needed function, so it should be there somewhere.

[RobG 1,892]

Well, then you can pass your first position in the array, for example charPos = 10, and then work your way back, charPos--;

[GeekDoc 226]

Well, then you can pass your first position in the array, for example charPos = 10, and then work your way back, charPos--;

Thought of that, too. Problem is that it requires knowing the number of digits in the supplied int, or having a fixed size for the string.

 

As with most programming problems, someone has solved this already. I just have to find where (libraries).

[RobG 1,892]

How about this then, a function that will determine the size of the array if(i<10) arraySize=1 else if(i<100) arraySize=2 and so on until you reach max int size.

Another way is to rebuild your initial array afterward since you have the size.

 

unsinged int charPos = 0;
while(myInt > 0) {           
  data[charPos] = 0x30 + (myInt % 10); 
  myInt /= 10;
  charPos++;
}

unsigend int size = charPos;
unsigned int reversed[size];
while(charPos >0){
charPos--;
reversed[charPos] = data[size-1-charPos];
}

[cde 334]

Counting number of digits in an int.

 

http://stackoverflow.com/questions/5545 ... tring-cast

 

Since we know its an unsigned 16bit int, so a number ranging from 0 to 65535

 

const unsigned int test[] = { 1, 10, 100, 1000, 10000 };

unsigned int digits = 0;

while(importantnumber >= test[digits]) ++digits;

 

Digits will be 0 for an int with value 0 (or nll or unintialized?) while 1 for 1-9, 2 for 10-99, etc.

[RobG 1,892]

Awesome!

[GeekDoc 226]

cde and Google to the rescue! Turns out that this (sprintf()) is not strictly in the C/C++ language, but is widely implemented in stdio libraries. Also, adding a couple of global char arrays (strings) made things a lot easier.

 

Easy, 4-line solution:

char* int_to_str(unsigned int i, char* the_str)
{
//sprintf() returns # chars, but this does not currently use the info
int total_chars; 
total_chars=sprintf(the_str, "%d", i);
return the_str;
}

 

Result:

 

On to capturing and working with the inputs!

 

EDIT: Just noticed I'm up to 1.8K! Going to have to a) hope the rest of the code doesn't add much, b)find ways to trim size, or c) wait for newer, higher capacity value-line chips (still waiting on samples). Probably will go with combo of a) and c).

[bluehash 1,581]

Looks like good progress!