Molecular Geometry

/*****************************************************************************

 main.cpp
 Molecular Geometry

 Created by Hayden Lueck on 2014-10-27.
 Copyright (c) 2014 Hayden Lueck. All rights reserved.

 Program Purpose: Get molecular shape based off of 2 atoms given by input file
                    molecules.txt

 main function:
    declares variables for use, sets up input and output files, checks they exist,
    goes through main loop while input file is not at EOF, does math based on given
    information, returns final output

 VAtom function:
    takes in string for atom V's symbol, and gives number based on that
 shape function:
    takes in integers for B and N and returns the shape for them

 input:
    an input file with the name molecules.txt, includes symbols for elements and
    a number on each line
 output:
    For each line it prints:
    "The geometrical shape of one [atom V] atom surrounded by [num b] [atom B] atoms is [shape]."

 limitations:
    needs very specific input from molecules.txt, and if it isn't formatted correctly the program
    won't work.

 *****************************************************************************/

#include <iostream>
#include <fstream>
#include <string>

/******  function protoyping ******/
int VAtom(std::string x);
std::string shape(int numB, int numN);

/****** main function ******/
int main() {

    std::string atomV, atomB, molecularShape; //declare strings
    int numV, numB, numE, numN; //declare integers
    std::ifstream inFile; //input file
    std::ofstream outFile; //output file

    inFile.open("molecules.txt"); //bind inFile to molecules.txt
    outFile.open("geometricalshapes.txt"); //bind outFile to geometricalshapes.txt

    /****** check files exist ******/
    if(!inFile){
        std::cout << "Cannot find input file molecules.txt Exiting..." << std::endl;
        return 1;
    }
    if(!outFile){
        std::cout << "Cannot find output file geometricalshapes.txt Exiting..." << std::endl;
        return 2;
    }

    /****** main loop ******/
    while(!inFile.eof()){ //while not end of file
        inFile >> atomV; //get string until whitespace
        inFile >> atomB; //get string until whitespace
        inFile >> numB; //get int until whitespace

        numV = VAtom(atomV); //get atom V's respective number
        numE = numV - numB; //set numE
        numN = numE / 2; //set numN
        molecularShape = shape(numB, numN); //get final molecular shape for output

        outFile << "The geometrical shape of one " << atomV << " atom surrounded by " << numB
        << ' ' << atomB << " atoms is " << molecularShape << "." << std::endl; //output string

    }

    return 0;
}

/****** VAtom function ******/
int VAtom(std::string atomName){
    //check string and return number based off of it
    if(atomName == "Be")
        return 3;
    else if (atomName == "C")
        return 4;
    else if(atomName == "Si")
        return 4;
    else if(atomName == "N")
        return 5;
    else if(atomName == "P")
        return 5;
    else if(atomName == "As")
        return 5;
    else if(atomName == "O")
        return 6;
    else if(atomName == "S")
        return 6;
    else if(atomName == "Se")
        return 6;
    else if(atomName == "F")
        return 7;
    else if(atomName == "Cl")
        return 7;
    else if(atomName == "Br")
        return 7;
    else if(atomName == "I")
        return 7;
    else if(atomName == "Xe")
        return 8;
    else //if none of the names match up
        return 999; //return an extreme outlier (easy to tell if a mistake is made on respective line)

}

/****** shape function ******/
std::string shape(int numB, int numN){
    //check both numbers and give shaped based off of them
    if(numB == 2 && numN == 0)
        return "linear";
    else if(numB == 2 && numN == 1)
        return "bent";
    else if(numB == 2 && numN == 2)
        return "bent";
    else if(numB == 2 && numN == 3)
        return "linear";
    else if(numB == 3 && numN == 0)
        return "trigonal planar";
    else if(numB == 3 && numN == 1)
        return "trigonal pyramidal";
    else if(numB == 3 && numN == 2)
        return "T-shaped";
    else if(numB == 4 && numN == 0)
        return "tetrahedral";
    else if(numB == 4 && numN == 1)
        return "seesaw";
    else if(numB == 4 && numN == 2)
        return "square planar";
    else if(numB == 5 && numN == 0)
        return "trigonal bipyramidal";
    else if(numB == 5 && numN == 1)
        return "square pyramidal";
    else if(numB == 6 && numN == 0)
        return "octahedral";
    else //if there isn't a case for the 2 numbers gives
        return "unknown"; //return "unknown"

}