Keith said:
Nicely done!
In cases like this, though, I think I'd argue that using casts or not
is largely a matter of taste. I find that I'm a little uncomfortable
with the way the constant 1.0 imposes its type on the rest of the
expression, bubbling up through multiple levels of the tree.
And I suppose that's inconsistent with most of what I've said about
using casts where implicit conversions would do the same job. Oh,
well.
I missed this. (A guy's gotta sleep some time.) Ben thinks that what's
happening here is a little too nuanced for me, but I think I can get my
head around it and bring the necessary machinery to bear:
dan@dan-desktop:~/source$ gcc -std=c99 -Wall -Wextra mort5.c -o out; ./out
1222567701 = 01001000110111101110011100010101
14 = 00000000000000000000000000001110
dan@dan-desktop:~/source$ cat mort5.c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <limits.h>
#define STRING "%13d = %s\n"
#define E_TYPE int
#define N 26
typedef E_TYPE e_type;
void bitstr (char *str, const void *obj, size_t n);
int
main (void)
{
int i, j;
e_type e;
char ebits[CHAR_BIT * sizeof e + 1];
srand (time (NULL));
j = rand ();
e = j;
bitstr (ebits, &e, sizeof e);
printf (STRING, e, ebits);
i = (j / (RAND_MAX + 1.0)) * N;
e = i;
bitstr (ebits, &e, sizeof e);
printf (STRING, e, ebits);
return 0;
}
void
bitstr (char *str, const void *obj, size_t n)
{
unsigned mask;
const unsigned char *const byte = obj;
while (n-- != 0)
{
mask = ((unsigned char) -1 >> 1) + 1;
do
{
*str++ = (char) (mask & byte[n] ? '1' : '0');
mask >>= 1;
}
while (mask != 0);
}
*str = '\0';
}
// gcc -std=c99 -Wall -Wextra mort5.c -o out; ./out
dan@dan-desktop:~/source$
I've seen now several versions of
i = (j / (RAND_MAX + 1.0)) * N;
What is happening to 1222567701 / (RAND_MAX + 1.0) * 26?
Of what type is (RAND_MAX + 1.0) ?
Thanks again for your thoughtful comments.
.text+0x58): undefined reference to `nextafter'