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  1. #define _LARGEFILE64_SOURCE
  2. #include <stdio.h>
  3. #include <sys/types.h>
  4. #include <sys/stat.h>
  5. #include <fcntl.h>
  6. #include <unistd.h>
  7. #include <stdlib.h>
  8. #include <time.h>
  9.  
  10. #define BLOCK_SIZE 1<<20ul
  11. #define ITERATIONS 1000
  12.  
  13. int main()
  14. {
  15.         char* p;
  16.         FILE* f;
  17.         struct timeval start, end;
  18.         double delta;
  19.         int fd, i, j;
  20.  
  21.         p = malloc(BLOCK_SIZE);
  22.         gettimeofday(&start, NULL);
  23.  
  24.         // f = fopen("dummy.bin", "w");
  25.         fd = open("dummy.bin", O_BINARY | O_DIRECT | O_CREAT | O_WRONLY);
  26.         f = fdopen(fd, "w");
  27.  
  28.         sync();
  29.  
  30.         for (i = 0; i < ITERATIONS; ++i)
  31.         {
  32.             for (j = 0; j < BLOCK_SIZE; ++j)
  33.                 p[j] = ((char)i)^((char)j);
  34.             fwrite(p, BLOCK_SIZE, 1, f);
  35.         }
  36.         fflush(f);
  37.         fclose(f);
  38.         free(p);
  39.  
  40.  
  41.         sync();
  42.  
  43.         gettimeofday(&end, NULL);
  44.         delta = ((end.tv_sec * (unsigned int)1e6 +   end.tv_usec) - 
  45.                          (start.tv_sec * (unsigned int)1e6 + start.tv_usec)) / 1.e6;
  46.  
  47.         printf("%.3f MB/s (%i Mb in %.2fs)\n", ITERATIONS / delta, ITERATIONS, delta);
  48.  
  49.         return 0;
  50. }
  51.  
  52.  
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.c: In function ‘main’:
prog.c:22: warning: implicit declaration of function ‘gettimeofday’
prog.c:25: error: ‘O_BINARY’ undeclared (first use in this function)
prog.c:25: error: (Each undeclared identifier is reported only once
prog.c:25: error: for each function it appears in.)
prog.c:25: error: ‘O_DIRECT’ undeclared (first use in this function)
prog.c:34: warning: ignoring return value of ‘fwrite’, declared with attribute warn_unused_result
stdout
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Standard output is empty
https://ideone.com/jk9yl
language:
C (gcc 8.3)
created:
13 years ago
visibility:
public

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