Middle three digits: Difference between revisions
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Initial Haskell version. |
Add C implementation |
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-2002: ****number of digits must be >= 3 and odd****
0: ****number of digits must be >= 3 and odd****</pre>
=={{header|C}}==
<lang C>#include <stdio.h>
#define E_SMALL 1
#define E_EVEN 2
static const char *errors[] = {"too small", "even length"};
int mid3(int num, char *buf)
{
int i = 2, mag = 1;
int tmp = num = num < 0 ? -num : num; /* Discard sign. */
/* A number's magnitude can be used to determine both
* its length and, in this case, the oddness thereof. */
while (tmp /= 10) mag *= 10;
if (mag < 100) return E_SMALL;
if (mag & 128) return E_EVEN;
while (num > 1000) {
num -= num / mag * mag; /* Chop left digit. */
num /= 10; /* Now the right. */
mag /= 100;
}
/* Populate a character buffer to handle zeroes. */
for (i = 2; i >= 0; num /= 10, --i)
buf[i] = num % 10 + '0';
return 0;
}
int main(void)
{
int num;
char buf[4] = "";
while (scanf("%d", &num) != EOF) {
printf("%d: ", num);
if ((num = mid3(num, buf)) == 0)
printf("%s\n", buf);
else
puts(errors[--num]);
}
return 0;
}</lang>
=={{header|C++}}==
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