revndup

revndup.c

#include <stdio.h>

void shodan_ndup(char* s) {
  char* p = s;
  for(; *s; ++s)
    if (*s != s[1])
      *p++ = *s;
  *p = 0;
}

void shodan_rev(char* s) {
  char* p = s;
  for(; *p ; ++p) {}
  if (p>s)
    for(--p; p>s; --p, ++s) { 
      const char t = *p; *p = *s; *s = t; 
    }
}

int main() {
  { char s[] = ""; shodan_rev(s); printf("%s\n", s); }
  { char s[] = "H"; shodan_rev(s); printf("%s\n", s); }
  { char s[] = "He"; shodan_rev(s); printf("%s\n", s); }
  { char s[] = "Hel"; shodan_rev(s); printf("%s\n", s); }
  { char s[] = ""; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "H"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "HH"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "HHh"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "HHhh"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "HHell"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "Hell"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "Hel"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "Hello world"; shodan_rev(s); printf("%s\n", s); }
  { char s[] = "HHellooo worldd"; shodan_ndup(s); printf("%s\n", s); }
  { char s[] = "HHellooo worldd"; shodan_rev(s); shodan_ndup(s); shodan_rev(s); printf("%s\n", s); }
}