Question

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Im trying to make this code recursive but for some reason it doesnt work

Im trying to write program using RECURSION to change multiple spaces to one space can anyone help ?
example “a_______b” changes to “a_b”
it is a task that im trying to do for a long time ! can anyone help ?

here i tried this but i think the design doesnt work for recursion

void text_r(char *str)
{
    char *dst = str;

            if(*str=='\0')return ;
            *dst++ = *str;
            if (isspace(*str)) {
                    do ++str; while (isspace(*str));
                    --str;
            }
          return text_r(str++);
} 

i wrote the code without recursion but i have problem in converting it

void compress_spaces(char *str)
{
char *dst = str;

    for (; *str; ++str) {
            *dst++ = *str;
            if (isspace(*str)) {
                    do ++str; while (isspace(*str));
                    --str;
            }
    }
    *dst = 0;

}

Answer 1

Recursive version (avoiding any iterative part, like while) using the same pointer, given twice as argument

void recur(char *str, char *out) {
  if (*str!=' ' || str[1]!=' ') *out++ = *str;
  if (*str) recur(str+1, out);
}

Recursive version having only one param

void recur(char *str) {
  static char *out = NULL;
  if (out == NULL) out = str;
  if (*str!=' ' || str[1]!=' ') *out++ = *str;
  if (*str) recur(str+1);
}

Iterative version

void iter(char *str) {
  char *out = str;
  do {
    if (*str!=' ' || str[1]!=' ') *out++ = *str;
  } while (*str++);
}

To be called like

  char str[] = "   abc  d e  f   ";
  // either recursive
  recur(str, str);
  // or iterative
  iter(str);