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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. #include <stdio.h>
  5. #include <stdlib.h>
  6. struct buffer
  7. {
  8.     int begin, end, size;
  9.     char *buf;
  10. };
  11. typedef struct buffer buffer;
  12. buffer* create_buffer(int size)
  13. {
  14.     buffer *b = calloc(1, sizeof(*b));
  15.     b->begin = b->end = 0;
  16.     b->size = size;
  17.     b->buf = calloc(size, sizeof(b->buf[0]));
  18.     return b;
  19. }
  20. int write_buffer(buffer *b, void *data, int size)
  21. {
  22.     char *d = (char *)data;
  23.     int i;
  24.     for (i = 0; i < size && b->begin != (b->end + 1) % b->size; ++i)
  25.     {
  26.         b->buf[b->end] = d[i];
  27.         b->end = (b->end + 1) % b->size;
  28.     }
  29.     return i;
  30. }
  31. int read_buffer(buffer *b, void *data, int size)
  32. {
  33.     char *d = (char *)data;
  34.     int i;
  35.     for (i = 0; i < size && b->begin != b->end; ++i)
  36.     {
  37.         d[i] = b->buf[b->begin];
  38.         b->begin = (b->begin + 1) % b->size;
  39.     }
  40.     return i;
  41. }
  42. int main(void)
  43. {
  44.     buffer* b = create_buffer(100);
  45.     for (int i = 0; i < 10; ++i)
  46.         write_buffer(b, &i, sizeof(i));
  47.     long long p;
  48.     while (read_buffer(b, &p, sizeof(p)) == sizeof(p))
  49.     {
  50.         printf("%d ", (int)p);  
  51.     }
  52.     return 0;
  53. }
Compilation error #stdin compilation error #stdout 0s 15232KB
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stdin
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Standard input is empty
compilation info 
prog.cpp: In function ‘buffer* create_buffer(int)’:
prog.cpp:14:23: error: invalid conversion from ‘void*’ to ‘buffer*’ [-fpermissive]
     buffer *b = calloc(1, sizeof(*b));
                 ~~~~~~^~~~~~~~~~~~~~~
prog.cpp:17:20: error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]
     b->buf = calloc(size, sizeof(b->buf[0]));
              ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
stdout
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Standard output is empty
https://ideone.com/qqvUHm
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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