Scope Error Within If Statement - Abstract Class

[bwiesn]

Need some help with a scope error I am getting at compile time at line 45. In the code below I have an abstract class, jar in which vector_jar and list_jar are derived from using vector and list respectively. At the beginning of the code we must request input to test either the vector_jar or list_jar. However, since the classes are only initiated within the scope of the if statement, it will not run with the rest of the code. As we don't want to have redundant code, is there a way to solve this?

#include <cstdlib>
#include <time.h>
#include <fstream>
#include <cstring>
#include "vector_jar.h"
#include "llist_jar.h"


void writeJarToFile(Jar& J1, string fileName)
{
	ofstream ofs(fileName.c_str());
	ofs << J1;
	ofs.close();
}


void readJarFromFile(Jar& J2, string fileName)
{
	ifstream ifs(fileName.c_str());	
	while(ifs)
	{
		Marble m1;
		ifs >> m1;
		J2.add(m1);		
	}
}


int main()
{
   srand(time(0));  // for random marbles
   int jarflag;
   
   // if the user enter 1, then you should test vector jars;
   // otherwise, enter 2 to test list jars.
   cout << "Which kind of jar do you want to test? "
      "(1 - vector jar; 2 - list jar)" << endl; 
   cin >> jarflag;
		 jarflag = 1;
		 //do testing as instructed; 
        // show a menu with choices to let the user to choose ways 
         //to generate vector jar objects: VectorJar	
		jarflag = 2; 
		//do testing as instructed; 
        // show a menu with choices to let the user to choose

	if(jarflag==1)
      {         	
      VectorJar jar1(10), jar2(10), jar3, jar4, jar5, J1, J2, J3;
	  
      }
    else if(jarflag==2)
      {         
        ListJar jar1(10), jar2(10), jar3, jar4, jar5, J1, J2, J3;
      }
   else
      {
        cout << "Wrong number entered. Testing list jar." << endl;
		LListJar jar1(10), jar2(10), jar3, jar4, jar5, J1, J2, J3;
      }

		//Testing Sequence
		 cout <<"Jar 1 was created with 10 randomly generated marbles"<<endl;
		 cout <<"Jar 2 was created with 10 randomly generated marbles"<<endl;
		 cout << "Contents of Jar 1:\n" << jar1;
		 cout << "Contents of Jar 2:\n" << jar2;
		 jar3.merge(jar1,jar2);
		 cout <<"Contents of the merge Jar 1 & 2:\n" << jar3;
		 jar4.intersection(jar1,jar2);
		 cout <<"Contents of the intersection of Jar 1 & 2:\n" << jar4;
		 jar5.difference(jar1,jar2);
		 cout <<"Contents of the difference of Jar 1 & 2:\n" << jar5;
         
		 //Begin Menu
		 char selection;
		 char removeToken;
		 string filename = "jar.out";
		 int generatedJarCount = 0;
		 bool hasWrittenFiles = false;
		 do {
			 cout	<< "Please choose from the following choices: " << endl
					<< "(a) Enter the number of marbles to create a jar." << endl 
					<< "(b) Print the jar to a file." << endl
					<< "(c) Read a jar from a file." << endl
					<< "(d) Remove a specific marble with color." << endl
					<< "(e) Remove a specific marble with size" << endl
					<< "(f) Test merge with 2 jars read from files, print the resulting jar to the file named \"merge.out\""<< endl
					<< "(g) Test complement (difference) with 2 jars read from files, print the resulting jar to the file named \"completion.out\"" << endl
					<< "(h) Test intersection with 2 jars read from files, print the resulting jar to the file named \"intersection.out\"" << endl
					<< "(i) Exit the program" << endl;
			cin >> selection;
			switch (selection)
			{
				case 'a':
				case 'A':
				{
					cout << "Please enter the number of marbles to generate a jar:";
					int n;
					cin >> n;
					if(generatedJarCount%2 == 0) {
						//J1(n); To FIX LATER
						cout << endl << "Jar J1 (re)generated with " << J1.marble_number() << " marbles." << endl;
						cout << J1;
					}
					else {
						//J2(n); To FIX LATER
						cout << endl << "Jar J2 (re)generated with " << J1.marble_number() << " marbles." << endl;
						cout << J2;
					}
					generatedJarCount++;
				}
					break;
				case 'b':
				case 'B':
				{
					if(generatedJarCount < 2) {
						cout << "You need to create two jars before they can be printed. (Try menu item 'a')" << endl;
						break;
					}
					writeJarToFile(J1, "jar1.in");			
					writeJarToFile(J2, "jar2.in");
					hasWrittenFiles = true;
				}
					break;
				case 'c':
				case 'C':
				{
					cout << "Please enter the filename you would like to read from:";
					cin >> filename;
					if(generatedJarCount%2 == 0) {
						readJarFromFile(J1, filename);
						cout << endl << "Jar J1 (re)generated with " << J1->marble_number() << " marbles." << endl;
					}
					else {
						readJarFromFile(J2, filename);
						cout << endl << "Jar J2 (re)generated with " << J2->marble_number() << " marbles." << endl;
					}
					generatedJarCount++;
				}
					break;
				case 'd':
				case 'D':
				{
					cout << "Please input the color you would like to remove from j1, (r,y,b,g):";
					cin >> removeToken;
					Marble m1;
					switch(removeToken) {
						case 'r': 			
							m1.set_color(Marble::Color(0));
							break;
						case 'y': 			
							m1.set_color(Marble::Color(2));
							break;
						case 'b': 			
							m1.set_color(Marble::Color(1));
							break;
						case 'g': 			
							m1.set_color(Marble::Color(3));
							break;
						default:
							cout << "Not a valid input" << endl;
							break;
					}
					J1.remove(m1);
				}
					break;
				case 'e':
				case 'E':
				{
					cout << "Please input the size you would like to remove from j1, (s/m/l):";
					cin >> removeToken;
					Marble m1;
					switch(removeToken) {
						case 's': 			
							m1.set_size(Marble::Size(0));
							break;
						case 'm': 			
							m1.set_size(Marble::Size(1));
							break;
						case 'l': 			
							m1.set_size(Marble::Size(2));
							break;
						default:
							cout << "Not a valid input" << endl;
							break;
					}
					J1.remove(m1);
				}
					break;
				case 'f':
				case 'F':
				{
					if(hasWrittenFiles) {
						readJarFromFile(J1, "jar1.in");
						readJarFromFile(J2, "jar2.in");
						J3.merge(J1,J2);
						writeJarToFile(J3, "merge.out");
					}
					else
						cout << "You have not written any files yet, and this operation requires two written files. (try menu item b)" << endl;
				}
					break;
				case 'g':
				case 'G':
				{
					if(hasWrittenFiles) {
						readJarFromFile(J1, "jar1.in");
						readJarFromFile(J2, "jar2.in");
						J3.intersection(J1,J2);
						writeJarToFile(J3, "intersect.out");
					}
					else
						cout << "You have not written any files yet, and this operation requires two written files. (try menu item b)" << endl;
				}
					break;
				case 'h':
				case 'H':
				{
					if(hasWrittenFiles) {
						readJarFromFile(J1, "jar1.in");
						readJarFromFile(J2, "jar2.in");
						J3.difference(J1,J2);
						writeJarToFile(J3, "difference.out");
					}
					else
						cout << "You have not written any files yet, and this operation requires two written files. (try menu item b)" << endl;
				}
					break;
			}
		} while(selection != 'i' || selection !='I');
}

[coercedman66]

looking at your source code i'll try to explain scope.
{
}
Defines a single scope. So any variable defined inside that scope can only be used there.
you need to define the variables outside the {} to be able to use it everywhere.

Something I want to note about the scope:
{
//defined here.
{
//define can use here.
}
}
//define not used here, does not exists to compiler.


You can use the define of a prevous scope, if the scope is inside a scope.

[bwiesn]

That is exactly my problem. I understand the scope concept. My problem is I need to implement a different instance of vector_jar and list_jar (lines 0 - 60) using the same testing code (lines 60-234) The person using this needs to be able to choose which instance to test.

[coercedman66]

You might have to make two sections of code that are the same, only difference is the ListJar is defined in one, and the VectorJar is defined in the other.