Error no match for call to (std :: vectorint) (int &)

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Error no match for call to (std :: vectorint) (int &)

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A function that looks for a number that the user enters on the screen, what happens is that the compiler gives me an error that I do not understand:

#include<iostream>
#include<string.h>
#include<vector>

using namespace std;

bool busqueda_recursiva(vector<int> array,int length, int x,int i);

int main (void) {

    int i=0;

    int buscado=0;
    vector<int> tabla(8);

    for (i=0; i<8; i++)
    {
        tabla(i)= i+1; //inicializar vector
    }  
    cout << "cual es el elemento que desea buscar" << endl;
    cin >> buscado;

    int b=busqueda_recursiva(tabla,8,buscado, i);

    if (b){
        cout << "el elemento " << buscado << "se encuentra en el vector"<< endl;
    }
    else {
        cout << " el elemento " << buscado << " no se encuentra en el vector" << endl;
    }
}

bool busqueda_recursiva(vector<int> array ,int length,int x, int i){ //no se le pone corchetes cuando se crea 
  length = array.size(); 
  if (length==0) { 
  cout << " el vector estÃ¡ vacÃo " << endl;
  return 0; 
  }
  else if (x==array[i]){ //apunta al primer elemento
  return 1;
 }
 else
{
  busqueda_recursiva(array,--length,x,++i);
  cout << "el elemento es  " << x << endl;
  return 1;
  }
}

The error that comes to me is this:

no match for call to (std::vector<int>) (int&)

What could be causing this error?

c++

asked by AER 28.04.2017 в 18:36

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2 answers

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score 0 · Answer 1

The error is found in the for that initializes the vector.

for (i=0; i<8; i++)
{
    tabla(i)= i+1; //inicializar vector <---------------- ERROR
}

To add values to the arrays of the class vector , push_back is used as shown below:

for (i=0; i<8; i++)
{
    tabla.push_back(i+1); //inicializar vector
}

On the other hand, if you want to modify the array, you must first have initialized it (as you do with vector<int> tabla(8); and then access a position that is not empty, for example: tabla[posicion] = nuevoValor ;

for (i=0; i<8; i++)
{
    tabla[i]= i+1; //inicializar vector
}

score 0 · Answer 2

Class vector does not have an overloaded operator function to access its elements, so the content of the first loop is wrong:

for (i=0; i<8; i++)
{
    tabla(i)= i+1; //inicializar vector
//       ^^^
}

Instead you should use, since you have already created 8 elements in the vector when building it, it is the index operator []

for (i=0; i<8; i++)
{
    tabla[i]= i+1; //inicializar vector
}

But of course, it does not make much sense to assign a predetermined number of positions and then do a fixed iteration. What happens if you then change the number of elments to 10? or you also update the limit in the loop or you will have errors. Here you should use the size() method of the vector:

for (i=0; i<tabla.size(); i++)
{
    tabla[i]= i+1; //inicializar vector
}

Even without this last change the program already compiles but ... what happens with this call?

int b=busqueda_recursiva(tabla,8,buscado, i);

If we review the program we will see that i is 8 ... we see what effect that value has:

bool busqueda_recursiva(vector<int> array ,int length,int x, int i){
  length = array.size();
  if (length==0) { 
  cout << " el vector esta vacio " << endl;
  return 0; 
  }
  else if (x==array[i]){ // <<--- AQUI
  return 1;
 }
 else
   // ...
}

In the line highlighted with the comment you can see that in the first call to the function you already run the risk of accessing an invalid memory position. It is the risk of reusing variables.

In my humble opinion the main should look more like this:

int main () { // (1)

    //(2)
    vector<int> tabla(8);

    for (int i=0; i<8; i++) // (3)
    {
        tabla[i]= i+1; //inicializar vector
    }  
    cout << "cual es el elemento que desea buscar" << endl;
    cin >> buscado;

    bool b=busqueda_recursiva(tabla,8,buscado, 0); // (4)

    if (b){
        cout << "el elemento " << buscado << "se encuentra en el vector"<< endl;
    }
    else {
        cout << " el elemento " << buscado << " no se encuentra en el vector" << endl;
    }
}

Where ...

In C ++, functions that do not receive arguments do not need void are redundant and unnecessary.

In C ++ (and from C99 as well) it is not necessary to declare the variables at the beginning of the function. Ideally, delay your statement as long as possible.

Loops for support variable declaration.

If the function returns bool then it stores the value in a variable of type bool . There is no point in converting the value to int and it can be a source of errors.

The supposed recursive function also has several problems:

bool busqueda_recursiva(vector<int> array ,int length,int x, int i){ // (1)
  length = array.size(); // (2)
  if (length==0) { 
  cout << " el vector esta vacio " << endl; // (3)
  return 0; // (4)
  }
  else if (x==array[i]){ //apunta al primer elemento (5) (6)
  return 1; // (4)
 }
 else
{
  busqueda_recursiva(array,--length,x,++i);
  cout << "el elemento es  " << x << endl; // (7)
  return 1; // (4) (8)
  }
}

Namely:

If you pass the vector by value you will make a copy of it in each recursive call. This is not very efficient either in time (although for that matter it is not a problem) or in memory (copying the vector a high number of times can fill the stack very quickly). It is preferable to pass a constant reference.

What good is it that the function receives an argument if you overwrite its value in the first line of the function?

Try not to use non-ASCII characters if you do not want to risk having strange messages

If the function returns a Boolean it is normal to use true and false instead of 1 and 0 . Remember that in C ++ (unlike C) the typing is strong and these things should be taken care of.

Do you not check the value of i before accessing the array? What if the user enters a non-existent value? If you look at your function, it will only return false when the vector is empty ... there are situations that you have not foreseen.

The comment of that line not only does not help but completely misleads. You are not accessing the first element but the one you touch in that iteration. To have bad comments is better not to have them.

x is the value that the user enters. What does this message provide? nothing.

In case you have not set this message it will be repeated 1 time per recursive call. Is it necessary to get the same message 6 times in a row? I do not think so.

You should go over the code a bit.