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