A C++ program to reverse each individual words in a sentence / string

#include <stdio.h>
#include <conio.h>
void reverse_string(char []);
void reverse_words(char []);
int main() {
  char line[100];
  puts("\n This is a c++  program to reverse words in a sentence \n ");
  puts("\n Please enter a string having many words \n ");
  gets(line);
  reverse_words(line);
  puts("\n Output after reversing each word of a given line : \n  ");
  puts(line);
     getch();
  return 0;
}
void reverse_words(char s[]) {
  char word[100];
  int k=0, j,i=0,m=0;
  while(s[i]) {                           //processing complete string
    while(s[k] != ' ' && s[k] != '\0') {    //extracting one word from string
      word[m] = s[k];
      k++;
      m++;
    }
    word[m] = '\0';
    m = 0;
    reverse_string(word);        // reverse the extracted word
    j = 0;
    while (word[j]) {    //copying the reversed word into original string
      s[i] = word[j];
      i++;
      j++;
    }
    while (s[i] == ' ')                  // skipping space(s)
                        { i++;  }
   k = i;                              // pointing to next word
  }
}
void reverse_string(char str[])
{
     int len, i=0;
     char tmp;
     while(str[i]) i++;  // calculate length of string
    len = i;
    for (i = 0; i < len/2; i++)
        {
        tmp  = str[i];
        str[i] = str[len-1-i];
        str[len-1-i] = tmp;
       }
}