Return string format from another struct

Question

I wanted to return the formatted string, which is created in the function des_Desconto, to format another string of the function itm_showItem more does not return anything.

Struct item

struct item{
  int ID;
  int qntd;
  float valor;
  char* descricao;
  Desconto* desconto;
};

Funcao da Struc item

char* itm_showItem(Item* i){
  char* saida;
  sprintf(saida, "ID: %d\nQuantidade: %d\nValor: %.2f\nDescricao: %s\nDesconto: %s\n",  
  i->ID,
  i->qntd,
  i->valor,
  i->descricao,
  des_showDesconto(i->desconto));
  return saida;
}

Struct desconto

struct desconto{
  int qntd;
  float valorDesconto;
};

Funcao da Struct desconto

char* des_showDesconto(Desconto* d){
  char* saida;
  sprintf(saida, "%.2f%% / %d item(ns)", des_getValor(d), des_getQntd(d));
  return saida;
}

Answer 1

That pointer there is not with memory allocated to it... My suggestion is to create a temporary variable of a slightly larger size and then allocate space based on the final size of this string, remembering to allocate 1 more space to the ' 0'.

char* des_showDesconto(Desconto* d){
    char* saida;
    char temp[500]; // tou usando 500 para o tamanho maximo da string, imaginando que nunca vá existir algo que chegue a esse valor.
    sprintf(temp, "%.2f%% / %d item(ns)", des_getValor(d), des_getQntd(d));
    saida = (char*) malloc(sizeof(char) * (strlen(temp) + 1));
    strcpy(saida, temp);
    return saida;
}

The same reasoning serves another function...

Try to organize better in the next questions so that people can execute your code... the way it is there does not compile: these functions getValor and getQntd for example, the definition is not in the code but as the name was suggestive enough, I managed to generate a code that runs. I’ll stick it down:

typedef struct Desconto{
   int qntd;
   float valorDesconto;
} Desconto;

typedef struct item{
   int ID;
   int qntd;
   float valor;
   char* descricao;
   Desconto* desconto;
 } item;

char* des_showDesconto(Desconto* d){
   char* saida;
   char temp[500]; // tou usando 500 para o tamanho maximo da string, imaginando que nunca vá existir algo que chegue a esse valor.
   sprintf(temp, "%.2f%% / %d item(ns)", d->valorDesconto, d->qntd);
   saida = (char*) malloc(sizeof(char) * (strlen(temp) + 1));
   strcpy(saida, temp);
   return saida; 
}


char* itm_showItem(item* i){
   char* saida;
   char temp[500];
   sprintf(temp, "ID: %d\nQuantidade: %d\nValor: %.2f\nDescricao: %s\nDesconto: %s\n",  
   i->ID,
   i->qntd,
   i->valor,
   i->descricao,
   des_showDesconto(i->desconto));
   saida = (char*) malloc(sizeof(char) * (strlen(temp) + 1));
   strcpy(saida, temp);
   return saida;
}

int main() 
{
    item i1;
    Desconto d;
    i1.ID = 10; i1.qntd = 2;
    i1.valor = 4.5;
    i1.descricao = (char*) malloc (sizeof(char) * 10);
    strcpy(i1.descricao, "aew papai");
    i1.desconto = &d;
    d.qntd = 1;
    d.valorDesconto = 0.05;
    printf("%s\n", itm_showItem(&i1));
}

Remember that these strings that are being returned from the functions are being allocated in the heap, it is nice to give them a free.