I got an error of C:\temp\hashTableProject\main.cpp|14|undefined reference to hash::Hash(std::string)
Anyone know how to solve this problem?
hash.h
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
#ifndef HASH_H
#define HASH_H
class hash{
public:
int Hash(string key);
};
#endif // HASH_H
hash.cpp
#include <iostream>
#include <cstdlib>
#include <string>
#include "hash.h"
using namespace std;
int hash::Hash(string key){
//int hash = 0;
int index;
index = key.length();
return index;
}
main.cpp
#include <iostream>
#include <cstdlib>
#include <string>
#include "hash.h"
using namespace std;
int main()
{
int index;
hash hashOb;
string traget = "Testing";
index = hashOb.Hash(traget);
cout << index << endl;
return 0;
}
Im using CodeBlock 13.12
There is only main.o file in obj folder. I dont know why the hash.o isn't there.
hash is an inbuilt template in "std" namespace.
Try removing using namespace std; lien and use namespace name as and when required.
Related
I have the following issue thrown by the compiler:
include/FlowChannel.h:14:21: error: ‘LatticeCell’ was not declared in this scope
std::vector grid;
when having these 3 header files (LatticeCell.h, FlowChannel.h and Utilities.h) and 2 cpp files including them(lbm.cpp and Utilities.cpp):
LatticeCell.h
#ifndef LATTICECELL_H
#define LATTICECELL_H
#include <iostream>
#include <vector>
#include <string>
#include <cmath>
/* Single cell */
using namespace std;
class LatticeCell{
private:
std::vector<double> matrix = {0,0,0,0,0,0,0,0,0};
unsigned int type; //fluid, no-slip, velocity or density
public:
//Constructor
LatticeCell(unsigned int inType){
type = inType;
}
};
#endif
FlowChannel.h
#ifndef FLOWCHANNEL_H
#define FLOWCHANNEL_H
#include <vector>
#include <string>
#include <cmath>
#include <iostream>
#include "LatticeCell.h"
using namespace std;
class FlowChannel{
private:
std::vector<LatticeCell> grid; //ERROR LINE
unsigned int dimX = -1;
unsigned int dimY = -1;
public:
FlowChannel(unsigned int nx, unsigned int ny){
dimX = nx+2;
dimY = ny+2;
unsigned int gridSize = dimX*dimY;
grid.reserve(gridSize);
initGrid(/*TODO Params*/);
}
};
#endif
lbm.cpp
#include <string>
#include <vector>
#include "LatticeCell.h"
#include "FlowChannel.h"
#include "Utilities.h"
int main(int argc, char** argv){
printsomething();
return 0;
}
Utilities.cpp
#include "LatticeCell.h"
#include "FlowChannel.h"
#include <string>
#include <iostream>
#include <cmath>
#include <vector>
using namespace std;
void printsomething(){
cout << "something" << std::endl;
}
double calcRelaxationTime(unsigned int ny , double reynolds, double uin){
return 3.0 * (uin * ny / reynolds) - 0.5;
}
Utilities.h
#ifndef UTILITIES_H
#define UTILITIES_H
#include "LatticeCell.h"
#include "FlowChannel.h"
#include <vector>
#include <cmath>
void printsomething();
#endif
Further my compiler flags are:
-Wall -std=c++17 -pedantic
For some reason I can't figure out, why LatticeCell wouldnt be a declared class in FlowChannel, due to it being included. Do you guys know whats wrong?
Edit: I added lbm.cpp, Utilities.cpp and Utilities.h so you guys see the full scope of the problem
You should check if the files are in the same directory.
I copy and paste your code in VS 2019 and it work for me,
here are the pictures
FlowChannel LatticeCell
It seems, that deleting #include 'LatticeCell.h' everywhere but in FlowChannel.h. I dont get the error 100% to be honest, as this wouldn't execatly cause an include loop that would induce such an error, but it works.
I'm trying to create a function that calculates the average of all the numbers in my array. But when I run the code the vector in my header says its undeclared. What should I change ?
I have tried putting #include in my header file and using namespace std; but it still doesn't fix my problem. I have also tried passing my function as reference.
Source.cpp
#include <iostream>
#include <string>
#include "math.h"
#include <vector>
using namespace std;
int main()
{
vector<int> notes;
notes.push_back(8);
notes.push_back(4);
notes.push_back(3);
notes.push_back(2);
cout << average(notes) << '\n';
}
math.cpp
#include "math.h"
#include <vector>
using namespace std;
int average(vector<int> tableau)
{
int moyenne(0);
for (int i(0); i < tableau.size(); i++)
{
moyenne += tableau[i];
}
return moyenne / tableau.size();
}
math.h
#ifndef MATH_H_INCLUDED
#define MATH_H_INCLUDED
int average(vector<int> tableau);
#endif MATH_H_INCLUDED
Add #include <vector>.
Use std::vector instead of just vector.
While at it, change the argument type to const&.
#ifndef MATH_H_INCLUDED
#define MATH_H_INCLUDED
#include <vector>
int average(std::vector<int> const& tableau);
#endif MATH_H_INCLUDED
You need to add #include <vector> in math.h instead of in math.cpp
I would like to implement a hash table example.
So for this aim, I have created one header, one hash.cpp and main.cpp files.
in my hash.cpp , I tried to run a dummy hash function which takes key value and turns into an index value. however, it throws an error(reference to 'hash' is ambiguous) whenever I try to create an object according to that hash class.
this is my main.cpp:
#include "hash.h"
#include <iostream>
#include <cstdlib>
#include <string>
#include <stdio.h>
using namespace std;
int main(int argc, const char * argv[]) {
hash hash_object;
int index;
index=hash_object.hash("patrickkluivert");
cout<<"index="<<index<<endl;
return 0;
}
this is my hash.cpp:
#include "hash.h"
#include <iostream>
#include <cstdlib>
#include <string>
#include <stdio.h>
using namespace std;
int hash(string key){
int hash=0;
int index;
index=key.length();
return index;
}
this is my hash.h
#include <stdio.h>
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
#ifndef __hashtable__hash__
#define __hashtable__hash__
class hash
{
public:
int Hash(string key);
};
#endif /* defined(__hashtable__hash__) */
Your hash class symbol is clashing with std::hash
A quick fix could be using a global namespace qualifier
int main(int argc, const char * argv[]) {
::hash hash_object;
but a better and recommended one would be to stop polluting your global namespace with
using namespace std;
and just using std::cout or std::endl when you need them.
You could also create your own namespace in case you're writing a library.
Besides, you have some capital letter typos here:
index = hash_object.hash("patrickkluivert");
^ I suppose you're referring to the Hash() function here
and here
int Hash(std::string key) {
^ this needs to be capital as well
int hash = 0;
in case you want to match your declaration and avoid cast/linking errors.
Your hash class is conflicting with std::hash. Stop using using namespace std; right now. If you want to make print statements shorter, try using std::cout; using std::endl;
How I can sent string variable into function in other file?
main.cpp:
#include <iostream>
#include <conio.h>
#include <string>
#include "headers.hpp"
using namespace std;
int main()
{
string a;
cout<<"Type:"<<endl;
cin>>a;
other(a);
getch();
return( 0 );
}
headers.hpp:
#ifndef HEADERS_HPP
#define HEADERS_HPP
void other(string a);
#endif
function.cpp:
#include "headers.hpp"
#include <iostream>
#include <math.h>
using namespace std;
void other(string a){
cout<<a;}
I don't know why it doesn't work. Do you know solution?
If you are saying it does not compile, you have to move the #include <string> from main.cpp into headers.hpp
I've got the problem with following code. It should get the object parameters from the txt file. Of course to get enum values correctly I've made this simple getline() function. I'm keep getting errors which I've tried to repair, but I still have no idea what's wrong. VC says that 'no instance of overloaded function getline matches the argument list'.
My code:
CKomputer.cpp
#include <iostream>
#include <cstdio>
#include <string>
#include <fstream>
#include "CKomputer.h"
#include "Procesor.h"
#include "KartaDzwiekowa.h"
#define TESTPR1
using namespace std;
void Komputer::pobierz(string nazwa)
{
#ifdef TESTPR1
cout<<"Uruchomiono metode pobrania stanu obiektu Komputer z pliku"<<endl;
#endif
ifstream plik_wejsciowy;
plik_wejsciowy.open(nazwa+".txt");
int zastos;
getline(plik_wejsciowy,linia);
zastos=atoi(linia.c_str());
zastosowanie=Komputer::zastosowanie(zastos);
plik_wejsciowy >> nazwa_komputera >> ram >> ile_kart_dzwiekowych >> zastos;
procesor.wczytaj(plik_wejsciowy);
if (ile_kart_dzwiekowych>0)
{
for (int i=0;i<ile_kart_dzwiekowych;i++)
karta_dzwiekowa[i].wczytaj(plik_wejsciowy);
}
plik_wejsciowy.close();
}
CKomputer.h
#pragma once
#include <stdlib.h>
#include <iostream>
#include <string>
#include <fstream>
#include "UrzadzenieElektroniczne.h"
#include "Procesor.h"
#include "KartaDzwiekowa.h"
using namespace std;
enum zastosowanie{biznes, gaming, grafika, programowanie};
class Komputer: public UrzadzenieElektroniczne
{
private:
Procesor procesor;
KartaDzwiekowa *karta_dzwiekowa;
protected:
string nazwa_komputera;
int ram;
int ile_kart_dzwiekowych;
public:
Komputer();
Komputer(string nazwa_komputera2, int ram2, int ile_kart_dzwiekowych2);
Komputer(const Komputer& k);
Komputer(int ilosc_kart);
~Komputer();
static int ile_Komputerow;
static int licz_ile_Komputerow();
void komp_info();
void wlaczenieurz();
void zapisz(string nazwa);
void pobierz(string nazwa);
zastosowanie zastos;
};