Syntax erorr in gethandler C++

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hi, I am having trouble correcting this syntax in the last line where Engine (e) should execute on a file, the program is should encrypt and decrypt a file depending on (preform)

C++

e.GetHandler(preform)->execute(file, ofile);

there is something wrong in

C++

execute(*file*,*ofile*);

What I have tried:

Full Code:-

C++

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

class Crypt {
private:
	virtual char hash(char c) = 0;
public:
	void execute(ifstream in, ofstream out) {
		while(in.good){
			char ne = hash(in.get);
			out << ne;
		}
	}
};

class Encrypt : public Crypt {
private:
	char hash(char c) {
		char a = c + 5;
		return a;
	}
};

class Decrypt : public Crypt {
	char hash(char c) {
		char a = c - 5;
		return a;
	}
};

class Engine {
public :
	Crypt* GetHandler(string k) {
		if (k == "encrypt") {
			static Encrypt E;
			return &E;
		}
		else 
		{
			static Decrypt D;
			return &D;
		}
	}
};

int main(){
	cout << "Please Select a mode\n" << endl;
	string preform;
	cin >> preform;
	string filename;
	cin >> filename;
	cout << "Please Enter a File Name\n" << endl;
	getline(cin, filename);
	ifstream file(filename, ios::binary);
	string outfile = "new";
	filename.append(filename);
	ofstream outfile(outfile, ios::binary);
	Engine e;
	e.GetHandler(preform)->execute(file, ofile);
}

Posted 5-Jan-21 2:35am

MohammedZr

Updated 5-Jan-21 7:13am

KarstenK

v2

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Comments

Patrice T 5-Jan-21 8:39am

Exact error message please.

4 solutions

Solution 1

by guessing in your code I would expect that the function needs pointers and you have variables written.

C++

e.GetHandler(preform)->execute(&file, &ofile);

You need to understand the pointer syntax better. A pointer is only the address AND NOT the value. And vice versa ...

Posted 5-Jan-21 2:52am

KarstenK

Solution 2

This won't even compile: ofile should be outfile.

I would also suggest that execute take its parameters by reference: ifstream& and ofstream&. It might work the way it is, but I don't know because I've never tried to pass them by value (which creates a copy).

Posted 5-Jan-21 2:55am

Greg Utas

Updated 5-Jan-21 2:56am

v2

Comments

KarstenK 5-Jan-21 10:34am

There are only disadvantages in creating copies, esp when complex objects.

MohammedZr 5-Jan-21 13:18pm

it was a mistake writing 'ofile', Tried with outfile and alias or reference and the same problem.

Solution 4

there are no solutions that work for me any suggestions

Posted 5-Jan-21 7:13am

MohammedZr

Comments

jeron1 5-Jan-21 13:17pm

Please just update your original post, as this is not a solution. Be as specific as possible when describing 'no solutions that work', show the full error text.

MohammedZr 5-Jan-21 13:20pm

I'm truly sorry I should be more aware, I tried all the solutions and I'm still facing the same problem

jeron1 5-Jan-21 13:52pm

Can you copy and paste the entire syntax error you are seeing, and the current code that has the latest changes, into your original post?

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CPallini · Accepted Answer · 2021-01-05T02:58:00

In C++ you have to use round brackets in method calls.

Quote:
while(in.good){
char ne = hash(in.get);
out << ne;
}

Should be instead

C++

while(in.good()){
			char ne = hash(in.get());
			out << ne;
		}

And (as suggested in other answers) there are other errors in you code. For instance streams must be passed by reference.

[update]
This should fix your code.

C++

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

class Crypt
{
  virtual char hash(char c) = 0;
public:
  void execute(ifstream & in, ofstream & out)
  {
    char c;
    while ( in.get(c) )
    {
      out.put(hash(c));
    }
  }
};

class Encrypt : public Crypt
{
  char hash(char c)
  {
    return (c+5);
  }
};

class Decrypt : public Crypt
{
  char hash(char c)
  {
    return (c-5);
  }
};

class Engine
{
public :
  Crypt & GetHandler(const string & k)
  {
    if (k == "encrypt")
    {
      static Encrypt E;
      return E;
    }
    else
    {
      static Decrypt D;
      return D;
    }
  }
};

int main()
{
  cout << "Please Select a mode\n" << endl;
  string preform;
  cin >> preform;
  cout << "Please Enter a File Name\n" << endl;
  string infilename;
  cin >> infilename;
  ifstream infile(infilename, ios::binary);
  string outfilename = "new";
  outfilename.append(infilename);
  ofstream outfile(outfilename, ios::binary);
  Engine e;
  e.GetHandler(preform).execute(infile, outfile);
}

However, being in inspired mood, you could also write

C++

#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
#include <functional>

using namespace std;

int main ()
{
  string mode, infilename;
  cout << "choose mode\n";
  cin >> mode;
  cout << "choose file\n";
  cin >> infilename;

  ifstream infile(infilename, ios::binary);
  infile >> noskipws;
  ofstream outfile("new"+infilename, ios::binary);

  istream_iterator<char> eos;
  istream_iterator<char> iit (infile);

  ostream_iterator<char> oit(outfile);

  function <char(char)>hash = mode == "encrypt" ? [](char c){ return c+5;} : [] (char c){ return c-5;};

  transform( iit, eos, oit, hash);

}

[/update]

Syntax erorr in gethandler C++

4 solutions

Solution 3

Solution 1

Solution 2

Solution 4

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