#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
  if (argc < 2) {
    printf("Usage: %s FILENAME\n", argv[0]);
    exit(1);
  }
  FILE *fp = fopen(argv[1],"r");
  int counter = 1;
  int c = fgetc(fp);
  char prev = (char)c;
  while(1){
    int d = fgetc(fp);
    //prev = c;
    if(d == EOF){
      //fputc((char)counter,stdout);
      fwrite(&counter,sizeof(int),1,stdout);
      fwrite(&prev,sizeof(char),1,stdout);
      break;
    }else if(d != prev){
      fwrite(&counter,sizeof(int),1,stdout);
      fwrite(&prev,sizeof(char),1,stdout);
      prev = (char)d;
      counter = 0;
    }else{
      counter++;
    }

  }
  fclose(fp);

  return 0;
}

[jfan14@fourier 02]$ cat tests/9.out tests-out/9.out
:a
b
c
d
ye
:a
b
c
d
xe