Reverse Words in Given Sentence without using any library method.

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

  int main() {
    char * str = "Hi how are you?";

    int start = 0;
    int end = -1;
    int i = 0;
    while (i <= strlen(str)) {
      if ( * (str + i) == ' ' || * (str + i) == '\0') {
        // print from end to start if end>=start
        if (end >= start) {
          for (int j = end; j >= start; j--) printf("%c", *(str + j));
          // make start = end+1 ... now start is pointing to space or \0
          start = end + 1;
          // print all spaces
          while ( * (str + i) == ' ') {
            printf(" ");
            start++;
            i++;
          }
          // make end = start-1 because end have to be less than start
          end = start - 1;

        }

      } else {
        // increment end
        end++;
        i++;
      }

    }

    return 0;
  }