Why am I getting this ifstream error?

Implicit instantiation of undefined template 'std::basic_ifstream<char,std::char_traits<char>>'

#ifndef MAPPER_H
#define MAPPER_H
#include <iostream>
#include <string>
#include <vector>
#include "KeyValue.h"
#include "Parser.h"

using namespace std;
class Mapper
{
public:
    Mapper(ifstream& infile);
    ~Mapper(void);
    void loadTokens();
    void showTokens();
    void map();
    void printMap();
    void printMap(string map_fileName);
private:
    ifstream inFile;  //<-- is where the error is happening
    vector<string> tokens;
    vector<KeyValue> map_output;
    Parser* parser;
};

#endif

I've even tried putting std::ifstream and it still doesn't work.

When I #include <fstream> instead of #include <iostream>, I get these errors in fstream.tcc and basic_ios.tcc:

'operator=' is a private member of 'std::basic_streambuf<char>'

And since that's part of the fstream library, obviously something i'm doing is wrong...

Anyone able to help?

You're missing

#include <fstream>

and you probably assign somthing to inFile which is not allowed.