Prime

/* 
 * File:   main.cpp
 * Author: K0ns3rv
 * Email: info@k0nserv.se
 * Description: Utility tool when working with prime numbers 
 * Created on den 11 juni 2010, 19:12
 * 
 * Usage: Use, modify and distribute as you wish. I do like credit :)
 */

#include <stdlib.h>
#include <iostream.h>
#include <fstream.h>
#include <vector.h>

/*
 * Checks if a given number is a prime number e.g only evenly divisible by itself and 1
 */
bool isPrime (int n) {
    for ( int i = 2; i < n; i++ ) {
        if ( n % i == 0 ) {
            return false;
        }
    }
    return true;
}

/*
 * Display the command syntax
 */
void displayOptions () {
    std::cout << "Invalid arguments " << std::endl;
    std::cout << "The following arguments are valid " << std::endl;
    std::cout << "-s Finds all numbers in the range 0 to second argument. Usage -s [max] [output] [filepath]" << std::endl;
    std::cout << "-f Factorize a given number, the second argument, as prime numbers. Usage -f [number]" << std::endl;
    std::cout << "-r Find all numbers in range first  argument to second argument. Usage -r [min] [max] [output] [filepath]" << std::endl;
    std::cout << "-c Check if given number is a prime. Usage -c [number]" << std::endl;
}

/*
 * Find all prime numbers in the the interval lowerRange to range
 * outputNumbers will ,if true, write the found primes the console. 
 * OutputPath will, if defined, write the numbers to a file
 * array will, if true, return the numbers as an std::vector<int>
 */
std::vector<int> find (int range, bool outputNumbers, char* outputPath = NULL, bool array = false, int lowerRange = 2) {
    std::vector<int> primes;
    int startPos; //Starting position in the input file
    bool fileOutput = true;
    ofstream file;

    if ( !array ) {
        std::cout << "Min: " << lowerRange << std::endl;
        std::cout << "Max: " << range << std::endl;
    }
    
    if ( outputPath != NULL ) {
        std::cout << "Selected output path: " << outputPath << std::endl;
    }
    
    else {
        fileOutput = false;
    }
    
    std::cout << "Running... \n" << std::endl;
    if ( fileOutput ) {
        file.open ( outputPath, ios::app );
        startPos = file.tellp ( );
    }


    for ( int i = lowerRange; i < range; i++ ) {
        if ( isPrime ( i ) ) {
            if ( array ) {
                primes.push_back ( i );
            }
            
            if ( outputNumbers ) {
                std::cout << i << std::endl;
            }
            
            if ( fileOutput ) {

                file << i;
                if ( i + 1 < range ) {
                    file << ",";
                }
                file << "\r\n";
            }
        }
    }
    if ( fileOutput ) {
        std::cout << "Wrote " << (int) file.tellp ( ) - startPos << " bytes to " << outputPath << std::endl;
        file.close ( );
    }
    return primes;
}

/*
 * Factorize a given number in primes e.g 6 = 3 * 2 and 25 = 5^2
 */
void factorize (int value) {
    bool running = true;
    std::vector<int> primes = find ( value, false, NULL, true );
    std::vector<int> result;

    while ( running ) {
        //std::cout << "value: " << value << std::endl;
        if ( isPrime ( value ) ) {
            result.push_back ( value );
            running = false;
            break;
        }
        
        for ( int loc = 0; loc < primes.size ( ); loc++ ) {
            if ( value % primes.at ( loc ) == 0 ) {
                //std::cout << "Divided by : " << primes.at(loc) << std::endl;
                result.push_back ( primes.at ( loc ) );
                value = value / primes.at ( loc );
                break;
            }
        }
    }
    std::cout << "Result: ";
    int numericResult = 1;
    for ( int loc = 0; loc < result.size ( ); loc++ ) {
        std::cout << result.at ( loc );
        
        if ( !(result.back ( ) == result.at ( loc )) ) {
            std::cout << " * ";
        }
        numericResult *= result.at ( loc );
    }
    std::cout << " = " << numericResult << std::endl;
}

/*
 * Check if a given number is a prime number
 */
void checkPrime (int c) {
    if ( isPrime ( c ) ) {
        std::cout << c << " is a prime number" << std::endl;
    }
    else {
        char* check;
        std::cout << c << " is not a prime number, run \"-f " << c << "\" to find out what prime numbers is it's factors" << std::endl;
        std::cout << "Would you like to do that now ? (Y/N): ";
        std::cin >> check;
        if ( !strcmp ( check, "Y\0" ) || !strcmp ( check, "y\0" ) ) {
            factorize ( c );
        }
    }
}

int main (int argc, char** argv) {
    if ( argc < 3 ) {//Invalid amount of arguments
        displayOptions ( );
        return 0;
    }
    else {
        if ( !strcmp ( argv[1], "-f\0" ) || !strcmp ( argv[1], "-F\0" ) ) {//Factorize
            factorize ( atoi ( argv[2] ) );
        }

        else if ( (!strcmp ( argv[1], "-s\0" ) || !strcmp ( argv[1], "-S\0" )) && argc > 3 ) {//search
            if ( argc == 5 ) {
                find ( atoi ( argv[2] ), !strcmp ( argv[3], "true\0" ), argv[4] );
            }
            else if ( argc == 4 ) {
                find ( atoi ( argv[2] ), !strcmp ( argv[3], "true\0" ) );
            }
            else {
                displayOptions ( );
            }
        }
        else if ( (!strcmp ( argv[1], "-r\0" ) || !strcmp ( argv[1], "-R\0" )) && argc > 4 ) {//Search with min and max
            if ( argc == 6 ) {
                find ( atoi ( argv[3] ), !strcmp ( argv[4], "true\0" ), argv[5], false, atoi ( argv[2] ) );
            }
            else if ( argc == 5 ) {
                find ( atoi ( argv[3] ), !strcmp ( argv[4], "true\0" ), NULL, false, atoi ( argv[2] ) );
            }
            else {
                displayOptions ( );
            }
        }
        else if ( (!strcmp ( argv[1], "-c\0" ) || !strcmp ( argv[1], "-c\0" )) ) {//check prime
            checkPrime ( atoi ( argv[2] ) );
        }

        else {
            displayOptions ( );
            return 0;
        }
    }
    return (EXIT_SUCCESS);
}