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  1. // Join items on output stream. (3.01)
  2.  
  3. #include <stdio.h>
  4.  
  5. void ostream_join(
  6.     const void *base, size_t nitems, size_t itemsize,
  7.     void (*putitem)(const void *item, FILE *stream),
  8.     const char* separator, FILE *stream, _Bool reverse)
  9. {
  10.     const char *first = base;
  11.     const char *last = first + nitems*itemsize;
  12.  
  13.     if (first != last) {
  14.         for (;;) {
  15.             if (reverse) {
  16.                 last -= itemsize;
  17.                 putitem(last, stream);
  18.             } else {
  19.                 putitem(first, stream);
  20.                 first += itemsize;
  21.             }
  22.             if (first == last)
  23.                 break;
  24.             fputs(separator, stream);
  25.         }
  26.     }
  27. }
  28.  
  29. // Use.
  30.  
  31. void putint(const void *item, FILE *stream)
  32. {
  33.     fprintf(stream, "%d", *(const int *) item);
  34. }
  35.  
  36. void print_ints(const int *a, size_t n, int end, _Bool reverse)
  37. {
  38.     putchar('[');
  39.     ostream_join(a, n, sizeof *a, putint, ", ", stdout, reverse);
  40.     putchar(']');
  41.     if (end != 0)
  42.         putchar(end);
  43. }
  44.  
  45. int main(void)
  46. {
  47.     int a[] = {1, 2, 3, 4};
  48.     print_ints(a, sizeof a / sizeof *a, '\n', 0);
  49.     print_ints(a, sizeof a / sizeof *a, '\n', 1);
  50.     return 0;
  51. }
Success #stdin #stdout 0s 5284KB
comments (?)
stdin
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Standard input is empty
stdout
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[1, 2, 3, 4]
[4, 3, 2, 1]
https://ideone.com/4GJdwd
language:
C (gcc 8.3)
created:
9 days ago
visibility:
public

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