CODEWITHSUNDEEP
cmallocrealloc
Felipe Balbino
Felipe Balbino

Reputation: 17

How to fix memmory allocation problem in the function below? (malloc)

I need to read a .txt file and to allocate each word from the file in a struct which is pointed from a vector of structs. I'll explain better below.

I appreciate your help.

My program is allocating only the first word of the file...

I know that the problem is in the function insere_termo() cause I've tested the fscanf whitout calling the function and it's doing ok.

STRUCTS

typedef struct _item
{
int conta; //contador
char *termo; //palavra
} Item;

typedef struct _mapa
{
int total; // número de itens no mapa
int blocos; // número de blocos de itens alocados
Item **lista; // vetor de ponteiros para itens
} Mapa;

MAIN

int main()
{
    Mapa mp;
    FILE *arq;
    int i, result, numPalavras;
    float x;
    int valor, max, min, mincar;
    char caminho[20];
    char termo[40];
    int tam;

    inicia_mapa(&mp);

    valor = menu();

HERE'S THE IMPORTANT PART OF MY CODE. WHERE I READ A FILE IN THE PATH GIVEN BY THE USER AND CALL THE FUNCTION insere_termo(); WHICH IS RESPONSIBLE FOR ALLOCATING EACH WORD IN THE struct.

switch (valor)
    {
    case 1:
        printf ("*Ler Arquivo* \n");
        printf("Digite caminho: ");
        scanf("%s", caminho);

        arq = fopen(caminho,"r"); // abrir arquivo no caminho especificado
            if (arq == NULL)
            {
                 printf("Erro, nao foi possivel abrir o arquivo\n");
            }

         while(fscanf(arq, "%s", termo) != EOF)
        {
        //Adiciona cada palavra no vetor
        insere_termo(&mp, termo);
        }

    break;

FUNCTIONS

INICIA_MAPA() IS THE FUNCTION WHICH IS RESPONSIBLE FOR INITIATING THE MAP, ALLOCATING A BLOCK OF 10 POINTERS TO THE STRUCT "ITEM".

INSERE_TERMO() IS THE FUNCTION WHICH IS RESPONSIBLE FOR ALLOCATING THE WORDS GIVEN BY THE TEXT FILE. THERE'S SOME PROBLEM WITH THE MEMORY ALLOCATION BUT I COULDN'T FIGURE IT OUT. ANY HELP IS WELCOME.

void inicia_mapa (Mapa *mp) //inicia um mapa vazio
{
    mp->lista = (Item**)malloc(BLOCK*sizeof(Item*));
    mp->total = 0;
    mp->blocos = 1;
}

void insere_termo (Mapa *mp, char *s) // insere um item com termo s e conta = 1
{

    if ((mp->total != 0)&&((mp->total%BLOCK) == 0))
    {
        mp->lista = (Item**)realloc(mp->lista,(mp->blocos+1)*BLOCK*(sizeof(Item*)));
        mp->blocos++;
    }

    mp->lista[mp->total] = (Item*) malloc(sizeof(Item)); // alocação dinâmica de item no mapa

    if (mp->lista[mp->total] == NULL)
    {
        printf("Erro na alocacao de memoria\n");
        exit(0);
    }

    strcpy(mp->lista[mp->total]->termo, s); // Insere termo s
    printf("%s\n", mp->lista[mp->total]->termo);
    mp->lista[mp->total]->conta++;
    mp->total++; // contagem do total

}

Upvotes: 1

Views: 53

Answers (2)

Felipe Balbino
Felipe Balbino

Reputation: 17

@chux thank you very much! It worked.

funcion updated:

void insere_termo (Mapa *mp, char *s) // insere um item com termo s e conta = 1 {

if ((mp->total != 0)&&((mp->total%BLOCK) == 0))
{
    mp->lista = (Item**)realloc(mp->lista,(mp->blocos+1)*BLOCK*(sizeof(Item*)));
    mp->blocos++;
}

mp->lista[mp->total] = (Item*) malloc(sizeof(Item)); // alocação dinâmica de item no mapa

if (mp->lista[mp->total] == NULL)
{
    printf("Erro na alocacao de memoria\n");
    exit(0);
}

mp->lista[mp->total]->termo = strdup(s); // Insere termo s
printf("%s\n", mp->lista[mp->total]->termo);
mp->lista[mp->total]->conta++;
mp->total++; // contagem do total

}

Upvotes: 0

chux
chux

Reputation: 153557

strcpy(mp->lista[mp->total]->termo, s); fails as mp->lista[mp->total]->termo is not yet assigned a value. Passing an uninitialized pointer pp to strcpy(p, ...) is undeifned behavior (UB).

Instead allocate memory, then copy with strcpy()

// strcpy(mp->lista[mp->total]->termo, s);
p->lista[mp->total]->termo = malloc(strlen(s) + 1);
strcpy(p->lista[mp->total]->termo, s);
// or
p->lista[mp->total]->termo = strdup(s);

Be sure to free memory when done.

Other problems may exist.

Upvotes: 1

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