#import <Foundation/Foundation.h>

extern double add(double x,double y);

extern double subtract(double x,double y);

extern double multiply(double x,double y);

extern double divide(double x,double y);

#import <Foundation/Foundation.h>

#import "MathOperation.h"

BOOL isAnOperator(const char value)

{

    return ((value == '+')||(value == '-')||(value =='*')||(value == '/'));

}

int main(int argc,const char * argv[])

{

    double result = 0;

    char operator = '\0';

    NSString * equation = [NSString stringWithUTF8String:argv[0]];

    NSArray *eqParts = [equation componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

    for (int n = 0; n < [eqParts count]; n++) {

        NSString * argString = [eqParts objectAtIndex:n];

        char firstChar = [argString characterAtIndex:0];

        if(isAnOperator(firstChar))

        {

            operator = firstChar;

            continue;

        }

        double newValue = [argString doubleValue];

        switch (operator) {

            case '+':

                result = add(result, newValue);

                break;

            case '-':

                result = subtract(result,newValue);

                break;

            case '*':

                result = multiply(result,newValue);

                break;

            case '/':

                result = divide(result,newValue);

            default:

                break;

        }

    }

    NSLog(@"%.3f",result);

}

//@implementation Calculator

//

//@end

#include "MathOperation.h"

double add(double x,double y)

{

    return x + y;

}

double subtract(double x,double y)

{

    return x - y;

}

double multiply(double x,double y)

{

    return  x * y;

}

double divide(double x,double y)

{

    return x / y;

}