parserv1

//basic mathematical parser v1.0
//author jakub molinski
//feel free to use, modify,
//copy and sell this code

#include <iostream>
#include <iomanip>
#include <sstream>
#include <cstdlib>
#include <conio.h>
#include <string>
#include <math.h>

using namespace std;

// list of functions
string parser(string);
string addition(string);
string subtraction(string);
string multiplication(string);
string division(string);
string exponentiation(string);
string sqroot(string);

// main function
int main()
{
    cout<<setprecision(50);
//  cout << parser("M_E+M_PI+10+10+M_PI2+M_E+M_PI+M_E");
    cout << parser("M_E+M_PI2") << endl;

    cout << addition("10+15.5") << endl;
    cout << subtraction("10-15.5") << endl;
    cout << multiplication("10*15.5") << endl;
    cout << division("10/15.5") << endl;
    cout << exponentiation("10^3") << endl;
    cout << sqroot("sqrt(81)") << endl;
    _getch();
    return 0;
}

//parser, main body
string parser(string text)
{

// initiation, variables
    string text_fixed = text;
    int e;
    int pi;
    int pi2;

// sources
    const string M_E_str = "2.71828182846";
    const string M_PI_str = "3.14159265358";
    const string M_PI2_str = "6.28318530717";

// first change, inserting constant values
    e = text_fixed.find("M_E");
    while(e != string::npos)
    {
        text_fixed.replace(e, 3, M_E_str);
        e = text_fixed.find("M_E");
    }
    pi = text_fixed.find("M_PI");
    while(pi != string::npos)
    {
        text_fixed.replace(pi, 4, M_PI_str);
        pi = text_fixed.find("M_PI");
    }
    pi2 = text_fixed.find("M_PI2");
    while(pi2 != string::npos)
    {
        text_fixed.replace(pi2, 5, M_PI2_str);
        pi2 = text_fixed.find("M_PI2");
    }

//

// returning modified text
    return text_fixed;
}

//basic addition
string addition(string to_add)
{
// variables
    int ch_place = to_add.find("+");
    string leftside_str = "";
    string rigthside_str = "";
    double leftside;
    double rigthside;
    double result;
    string result_str;

// finding the left and the right side of "+" character
    for(int i = 0; i < ch_place; i++)
    {
        leftside_str += to_add[i];
    }
    for(int i = ++ch_place; i < to_add.length(); i++)
    {
        rigthside_str+= to_add[i];
    }

// converting string into double
    leftside = atof(leftside_str.c_str());
    rigthside = atof(rigthside_str.c_str());

// calculating the result
    result = leftside + rigthside;

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}

//basic substraction
string subtraction(string to_sub)
{
// variables
    int ch_place = to_sub.find("-");
    string leftside_str = "";
    string rigthside_str = "";
    double leftside;
    double rigthside;
    double result;
    string result_str;

// finding the left and the right side of "-" character
    for(int i = 0; i < ch_place; i++)
    {
        leftside_str += to_sub[i];
    }
    for(int i = ++ch_place; i < to_sub.length(); i++)
    {
        rigthside_str+= to_sub[i];
    }

// converting string into double
    leftside = atof(leftside_str.c_str());
    rigthside = atof(rigthside_str.c_str());

// calculating the result
    result = leftside - rigthside;

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}

//basic multiplication
string multiplication(string to_mul)
{
// variables
    int ch_place = to_mul.find("*");
    string leftside_str = "";
    string rigthside_str = "";
    double leftside;
    double rigthside;
    double result;
    string result_str;

// finding the left and the right side of "*" character
    for(int i = 0; i < ch_place; i++)
    {
        leftside_str += to_mul[i];
    }
    for(int i = ++ch_place; i < to_mul.length(); i++)
    {
        rigthside_str+= to_mul[i];
    }

// converting string into double
    leftside = atof(leftside_str.c_str());
    rigthside = atof(rigthside_str.c_str());

// calculating the result
    result = leftside * rigthside;

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}

//basic division
string division(string to_div)
{
// variables
    int ch_place = to_div.find("/");
    string leftside_str = "";
    string rigthside_str = "";
    double leftside;
    double rigthside;
    double result;
    string result_str;

// finding the left and the right side of "/" character
    for(int i = 0; i < ch_place; i++)
    {
        leftside_str += to_div[i];
    }
    for(int i = ++ch_place; i < to_div.length(); i++)
    {
        rigthside_str+= to_div[i];
    }

// converting string into double
    leftside = atof(leftside_str.c_str());
    rigthside = atof(rigthside_str.c_str());

// calculating the result
    result = leftside / rigthside;

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}

//basic exponentiation
string exponentiation(string to_exp)
{
// variables
    int ch_place = to_exp.find("^");
    string leftside_str = "";
    string rigthside_str = "";
    double leftside;
    double rigthside;
    double result;
    string result_str;

// finding the left and the right side of "^" character
    for(int i = 0; i < ch_place; i++)
    {
        leftside_str += to_exp[i];
    }
    for(int i = ++ch_place; i < to_exp.length(); i++)
    {
        rigthside_str+= to_exp[i];
    }

// converting string into double
    leftside = atof(leftside_str.c_str());
    rigthside = atof(rigthside_str.c_str());

// calculating the result
    result = pow(leftside,rigthside);

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}

//basic square root
string sqroot(string to_root)
{
// variables
    double root;
    double result;
    string result_str;

// extracting the number
    to_root.erase(0, 5);
    to_root.erase((to_root.length()-1), 1);

// converting string into double
    root = atof(to_root.c_str());

// calculating the result
    result = pow(root,0.5);

// converting double into string
    ostringstream strs;
    strs << result;
    result_str = strs.str();

// returning calculated value
    return result_str;
}