二进制树中的根始终为NULL

Question

The program should read a txt, store all the words alphabetically and print them in order, with the number of times the word appears on the txt.

The problem seems to be in the Insert method, because it never prints TEST, so it seems the pAux is always NULL for some reason. And because of that, the Print method returns in his first call.

What am I doing wrong?

tree.h

#ifndef TREE_H_
#define TREE_H_

typedef struct Item{
    char* key;
    int no;
} TItem;

typedef struct No{
    TItem item;
    struct No* pLeft;
    struct No* pRight;
} TNo;

void TTree_Insert (TNo**, char[]);
void TTree_Print (TNo*);

#endif

tree.c

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

TNo* TNo_Create (char* c){
    TNo* pNo = malloc(sizeof(TNo));
    pNo->item.key = malloc(sizeof(char)*strlen(c));
    strcpy(pNo->item.key, c);
    pNo->item.no = 1;
    pNo->pLeft = NULL;
    pNo->pRight = NULL;
    return pNo;
}

void TTree_Insert (TNo** pRoot, char word[80]){
    char* c = malloc(sizeof(char)*strlen(word));
    strcpy(c, word);
    TNo** pAux;
    pAux = pRoot;
    while (*pAux != NULL){
        if (strcmp(c, (*pAux)->item.key) < 0) pAux = &((*pAux)->pLeft);
        else if (strcmp(c, (*pAux)->item.key) > 0) pAux = &((*pAux)->pRight);
        else{
            (*pAux)->item.no++;
            return;
        }
    }
    *pAux = TNo_Create(c);
    return;
}

void TTree_Print (TNo *p){
    if (p == NULL) return;
    TTree_Print (p->pLeft);
    printf("%s - %d", p->item.key, p->item.no);
    TTree_Print (p->pRight);
}

main.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "tree.h"

int main(){
    TNo* pRoot = NULL;
    FILE* txt = fopen("Loremipsum.txt", "r");
    char aux[80];
    int c, x = 0;

    while ((c = fgetc(txt)) != EOF){
        while (!(isalpha((char)c))) c = fgetc(txt);
        while (isalpha((char)c)) {
            if (isupper((char)c)) c = c+32;
            if (islower((char)c)) aux[x++] = (char)c;
            c = fgetc(txt);
        }
        aux[x] = '\0';
        TTree_Insert(&pRoot, aux);
        x = 0;
        aux[0] = '\0';
    }
    TTree_Print(pRoot);
    fclose(txt);
    return 0;
}

Answer 1

I did not look through all your code. I will answer only your question. You have to pass pRoot to TTree_Insert by reference. Otherwise you pass its copy to the function and any changes of the copy within the function do not influence the original value.

For example

void TTree_Insert ( TNo **pRoot, char word[80] ){
    char* c = malloc(sizeof(char)*strlen(word) + 1 ); // <==
    strcpy( c, word ); // <==
    TNo* pAux;
    pAux = *pRoot;        
    //...

And in main you have to call the function like

TTree_Insert( &pRoot, aux );

Take into account that you have to adjust all other code of the function. For example

void TTree_Insert( TNo **pRoot, const char word[80] )
{
    char* c = malloc( sizeof( char ) * strlen( word ) + 1 );

    strcpy( c, word );

    TNo **pAux = pRoot;

    while ( *pAux != NULL )
    {
        printf("TESTE");
        if ( strcmp(c, ( *pAux )->item.key ) < 0 )
        {
            pAux = &pAux->pLeft;
        }
        else if ( strcmp(c,  ( *pAux )->item.key ) > 0 )
        {
             pAux = &pAux->pRight;
        }
        else
        { 
            ( *pAux )->item.no++;
            break;
        }
    }

    if ( *pAux == NULL ) *pAux = TNo_Create(c);

    return;
}

I hope it will work.:)

Answer 2

pRoot is initially NULL , and you never change it later.

so it seems the pAux is always NULL for some reason

Well, that's the reason... why don't you use a debugger or do some printing?