Welcome to the Lounge

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
using namespace std;

struct elemento {
    char valor[100];
    struct elemento *prox;
    struct elemento *ant;
    struct elemento *down;
    struct elemento *up;
    struct elemento *backtostart;

};
typedef struct elemento ELEM;
ELEM *head = NULL;

int oldornew=0; //will determine if it is a new word or a old word (0 stands for old, 1 stands for new)
int wordexists=0; // will determine if a word does not have to be registered again (0 stands for old, 1 stands for new)

void Speak(ELEM* start, char valor[100]);
void AddWord(ELEM* start, char valor[100]);
void DivideWordsforAdd(ELEM* start, char valor[100]);
void DivideWordsforSpeak(ELEM* start, char valor[100]);
void Hear(ELEM* start, char valor[100]);
void CheckifExist (ELEM* start, char valor[100]);

void Speak(ELEM* start, char valor[100]){
    int newword=0;
    ELEM *elem = start->prox;
    while(elem->prox!=NULL){
        elem=elem->prox; //go to the last element
    }
    while(elem){
        int written=1;
        for(int i=0;i<100;i++){ //check if the word was written
            if(elem->valor[i]==valor[i] || valor[i]==0){
                if(valor[i]==' ' || valor[i]==0){
                    break;
                }
            }else{
                written=0;
            }
        }
        if(written==1){
            if (elem->down==NULL){
                newword=1; //do a check for a new word
                break;
            }
        }
        elem=elem->ant;
    }
    if(newword==0){
        elem=start->prox;
        while(elem->prox!=NULL){
            elem=elem->prox; //go to the last element
        }
    }
    while (elem){
        if (newword==1){ //new word
            int num=0;
            while(elem->valor[num]!=' '){
                num++;
            }
            if (elem->down==NULL){
                cout<<"Me: What is ";
                for(int i=0;i<num;i++){
                    cout << elem->valor[i];
                }
                cout << " ?" << endl;
                oldornew=1;
                break;
            }
        }else{ //if there is no new word
            int match=1;
            for(int i=0;i<100;i++){   //check if its the right word to output
                if (elem->valor[i]==valor[i] || valor[i]==0){
                    if(valor[i]==0 || valor[i]==' '){
                        break;
                    }
                }else{ //if it is a different value
                    match=0;
                }
            }
            if (match==1){
                for (int i=0;i<100;i++){
                    if(elem->valor[i]!=' '){
                        cout << elem->valor[i];
                    }else{
                        cout<<": "<<endl;
                        break;
                    }
                }
                elem=elem->down;
                while (elem->prox!=NULL){ //goto last element
                    elem=elem->prox;
                }
                while (elem){
                    for(int i=0;i<100;i++){
                        if(elem->valor[i]!=' ' || (elem->valor[i]==' ' && elem->valor[i+1]!=' ')){ //this makes sure the whole sentence gets printed
                            cout<<elem->valor[i];
                        }
                    }
                    if (elem->ant==NULL){
                        break;
                    }
                    elem=elem->ant;
                    cout<<endl;
                }
                cout<<endl<<endl;
                oldornew=0;
            }
        }
        if (elem->up){
            elem=elem->up;
        }
        elem = elem->ant;
    }
    cout<<endl;
    if (oldornew==1){
        Hear(elem,valor);
    }
}

void AddWord(ELEM* start, char valor[100]){
    ELEM *elem = (ELEM*)malloc(sizeof(ELEM));
    if (oldornew==1){ //if it is a sub word
        if (valor[0]==0){ //check if first value is [enter]
            oldornew=0;
            for(int i=0;i<100;i++){
                if(valor[i]==0){
                    valor[i]=' ';
                }
            }
            Hear(start->backtostart,valor); //Call Hear with 'start' element in parameters
        }
        for(int i=0;i<100;i++){
            if(valor[i]==0){
                valor[i]=' ';
            }
        }
        for(int i=0;i<100;i++){
            elem->valor[i]=' ';
        }
        for(int i=0;i<100;i++){
            if (valor[i]==' '&& valor[i-1]==' '){ //transfer every word until two spaces found (if bug appears, might remove && valor[i-1]==' ')
                break;
            }
            elem->valor[i] = valor[i];
        }
        elem->down=NULL;
        elem->ant=NULL;
        elem->up=start;
        if (start->down==NULL){
            elem->prox=NULL;
        }else{
            elem->prox=start->down;
            elem->prox->ant=elem;
        }
        start->down=elem;
        Hear(start,valor);
    }else{ //if is is a main word
        for(int i=0;i<100;i++){
            if(valor[i]==0){
                valor[i]=' ';
            }
        }
        for(int i=0;i<100;i++){
            elem->valor[i]=' ';
        }
        for(int i=0;i<100;i++){
            if (valor[i]==' ' && valor[i-1]==' '){//stop transferring the word at space key (if bug appears, might change ' ' to 0... or not)
                break;
            }
            elem->valor[i] = valor[i];
        }
        elem->down=NULL;
        elem->up=NULL;
        elem->ant=NULL;
        if (start->prox!=NULL){
            elem->prox=start->prox;
            elem->prox->ant=elem;
        }else{
            elem->prox=NULL;
        }
        elem->backtostart=start;
        start->prox=elem;
    }
}

void CheckifExist(ELEM* start, char valor[100]){
        int same=0;
        int checkfornew=1;
        ELEM* elem=start->prox;
        while(elem){
            for(int i=0;i<100;i++){ //check if word exists
                if(elem->valor[i]==valor[i] || valor[i]==0){
                    same++;
                    if (valor[i]==0 || valor[i]==' '){
                        checkfornew=0;
                        break;
                    }
                }else{
                    break;
                }
            }
            elem=elem->prox;
        }
        if (checkfornew==1){ //return to add new word to database
            wordexists=1;
            return;
        }else{
            wordexists=0;
        }
}

void DivideWordsforSpeak(ELEM* start,char valor[100]){
    char word[100];
    int k=0;
    for(int i=0;i<100;i++){
        word[k]=valor[i];
        if (valor[i]==' '){
            if (valor[i-1]!=' '){
                Speak(start,word);
                for(int j=0;j<i;j++){ //reset char array (word)
                    word[j]=' ';
                }
            }
        k=-1;
        }
    k++;
    }
    Hear(start,valor);
}

void DivideWordsforAdd(ELEM* start, char valor[100]){
    if (oldornew==1){
        AddWord(start,valor);
    }else{
        char word[100];
        int k=0;
        for(int i=0;i<100;i++){
            word[k]=valor[i];
            if (valor[i]==' '){
                if (valor[i-1]!=' '){
                    CheckifExist(start,word);
                    if (wordexists==1){
                        AddWord(start,word); //send word including the last space key
                    }
                    for(int j=0;j<i;j++){ //reset char array (word)
                        word[j]=' ';
                    }
                }
            k=-1;
            }
        k++;
        }
        DivideWordsforSpeak(start,valor);
    }
}

void Hear(ELEM* start, char valor[100]){
    cout<<"You: ";
    char x[100];
    for(int i=0;i<100;i++){
        x[i]=' ';
    }
    cin.getline(x,100);
    cout << endl;
    DivideWordsforAdd(start,x);
}

int main()
{
    head = (ELEM*)malloc(sizeof(ELEM));
    head->valor[0] = 's';
    head->valor[1] = 't';
    head->valor[2] = 'a';
    head->valor[3] = 'r';
    head->valor[4] = 't';
    head->prox=NULL;
    head->ant=NULL;
    head->down=NULL;
    head->up=NULL;
    head->backtostart=NULL;
    cout << "Hello! I am AI to talk." << endl << endl << "You: ";
    char x[100];
    for(int i=0;i<100;i++){
        x[i]=' ';
    }
    cin.getline(x,100);
    cout << endl;
    DivideWordsforAdd(head,x);
    return 0;
}