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Guess the number/With feedback (player): Difference between revisions
Guess the number/With feedback (player) (view source)
Revision as of 22:49, 31 August 2013
, 10 years ago→{{header|C}}
Line 168:
Awwwright</pre>
A hacky solution using <tt>bsearch()</tt> and pointers to represent integers. Although the pointers do not point to valid things, <tt>bsearch()</tt> doesn't actually dereference the pointers or care what they point to; it just passes them to the comparator and searches the space of pointers. We can use that to search any space of integers.
{{trans|Java}}
<lang c>#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
enum {
LOWER = 0,
UPPER = 100,
KEY = LOWER-1 // some value that is not in the valid range
};
char dummy;
// A pointer to represent the integer 0, and the basis of our integer-as-pointer
// representation. We can't use the null pointer because bsearch() returns that
// for not found.
#define ZERO ((void *)&dummy)
int get_value(int x) {
if (x == KEY)
return 0;
printf("My guess is: %d. Is it too high, too low, or correct? (H/L/C) ", x);
char input[2] = " ";
scanf("%1s", input);
switch (tolower(input[0])) {
case 'l':
return -1;
case 'h':
return 1;
case 'c':
return 0;
}
fprintf(stderr, "Invalid input\n");
exit(1);
return 0;
}
int my_cmp(const void *x, const void *y) {
return get_value(x - ZERO) - get_value(y - ZERO);
}
int main() {
printf("Instructions:\n"
"Think of integer number from %d (inclusive) to %d (exclusive) and\n"
"I will guess it. After each guess, you respond with L, H, or C depending\n"
"on if my guess was too low, too high, or correct.\n",
LOWER, UPPER);
void *result = bsearch(ZERO + KEY, ZERO + LOWER, UPPER-LOWER, 1, my_cmp);
if (result == NULL)
fprintf(stderr, "That is impossible.\n");
else
printf("Your number is %d.\n", (int)(result - ZERO));
return 0;
}</lang>
=={{header|C++}}==
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