sizeof(int) troubleshooting

Forum 2005-2010 (read only) Software Syntax & Programs
1

int test = 1000;
Serial.print((sizeof(test)/sizeof(int)));

This example outputs: 1
Shouldn't it output 4?, maybe i'm just lost?

2

I mean:

int test = 1000;
Serial.print(sizeof(test)/sizeof(int));

3

sizeof(test) is 2
sizeof(int) is 2
2 / 2 = 1

If you're trying to find out how many bytes an int occupies, I think you mean to say:

Serial.print(sizeof(int));

-Mike

4

okey,

Acctually what i need is something to get the length of the int.

int i=1000; <--- length 4.

5

Ah, you wish a function to return the number of significant digits of the contents of an integer variable?

6

If you don't mind using some floating point, you could do it like this

#include <math.h>

int numdigits(int i)
{
        int digits;

        i = abs(i);
        if (i < 10)
          digits = 1;
        else
          digits = (int)(log10((double)i)) + 1;
        return digits;
}

If you don't want to use floating point, you will need to have a loop that counts how many times you can divide the integer by 10 until it becomes zero.

-Mike

7

Another way that is less elegant

int numdigits(int i)
{
        char str[20];

        sprintf(str,"%d",abs(i));
        return(strlen(str));
}

Note that for negative numbers, the minus sign is not counted as a digit. If you want the minus sign to count, change the "abs(i)" to "i".