split int into a char array

Projects Programming
1

Hello, I need to split an int into a char array so I can use a buzzer to beep the individual digits.

But I cant seem to to turn an int into a char

Thanks.

2

You mean you want to print the value into a string? By individual numbers you mean individual decimal digits?

sprintf prints to a string (char array).

  char buffer [7] ; // long enough for 16 bit integer, sign, 5 digits and null.
  sprintf (buffer, "%i", value) ;  // print into buffer
3

Thanks so much for this, but what does the %i do?

5

There is a link to the AVR GCC library functions on the reference page on this site. But it should be made much more prominent.

6

If you want the digits of an int, you are after the division and remainder operations.

In C, division '/' of ints always rounds towards zero. And remainder '%' give you the remainder.

So for a two digit number, x/10 and x%10 give you the two digits.

For a (say) five digit number, the code is

int x = some_number;

for(int i = 10000; i > 0; i /= 10) {
  beep((x/i) % 10 ); // zero to 9
 }
7

The sprintf() function is very powerful, but usually you only use a fraction of its functionality. As a result, you end up using more memory than necessary. Consider the following program:

void setup() {

  int i;
  int val = 32111;
  char buffer [7] ; // long enough for 16 bit integer, sign, 5 digits and null.

  Serial.begin(9600);

//  sprintf (buffer, "%i", val);    // print into buffer
  itoa(val, buffer, 10);            // value, char array, base

  for (i = 0; buffer[i]; i++) {
    Serial.print(buffer[i]);
    Serial.print(" ");
  }
}

void loop() {
}

If you comment out the itoa() function call and use sprintf(), the compiled code uses 3298 bytes of memory. As it stand above, the same program compiles to 1938 bytes.