two assignments

sum of two matrices
and print out a matrix

// dfgdfdfg.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <fstream>
// within iostream
// istream cin;
// ostream cout;
using namespace std;

bool aComposite[1024] = { true, true };
bool isPrime(int n)
{
    return ! aComposite[n];
}

void setupLookupTable()
{
    for (int i = 2; i < 1024; i++)
    {
        // is this number i am visiting
        // already marked off as composite
        if (aComposite[i] == false)
            for (int j=i+i; j < 1024; j+=i)
                aComposite[j] = true;
    }

}

void print(const int a[], int capacity)
{
    for (int i = 0; i < capacity; i++)
        cout << a[i] << ' ';
    cout << endl;
}

void add(const int a[], const int b[], int c[], int capacity)
{
    for (int i = 0; i < capacity; i++)
        c[i] = a[i] + b[i];
}

void subtract(const int a[], const int b[], int c[], int capacity)
{
    for (int i = 0; i < capacity; i++)
        c[i] = a[i] - b[i];
}

void mult(const int a[], int scalar, int b[], int capacity)
{
    for (int i = 0; i < capacity; i++)
        b[i] = a[i] * scalar;
}

int main() {
    setupLookupTable();
    for(int k = 0; k < 1024; k++)
        if (isPrime(k))
            cout << k << endl;
    string s, t;
    int u;

    ifstream jin;
    jin.open("c:/josh/myfirstinput.txt");
    jin >> s;
    jin >> t;
    cout << s << t << endl;
    jin.close();

    ofstream jout;
    jout.open("c:/josh/myfirstoutput.txt");
    for(int i = 0; i < 10; i++)
        jout << i << " ";
    jout << endl;
    jout.close();
    system("PAUSE");

   int A[3][3] =
   {
       { 4, 6, 0},
       { 6, 0, 1},
       { -1,3, 5}
   };
   int B[3][3];
   int C[3][3];
   int x[5] = {3,4,5,2,3};
   int y[5] = {1,1,0,2,3};
   int z[5];
   int a[5];
    // a = x * 6
   add(x, y, z, 5);

   print(z, 5);

   mult(y, 6, z, 5);
   print(z, 5);
  
   return 0;
}

Code from class today; also recursive definition of division via repeated subtraction

int mult(int x, int y)
{
    int result = 0;
    for (int i = 0; i < y; i++)
        result += x;
    return result;
}

int mult(int x, int y)
{
    if (y == 0) return 0;
    if (y == 1) return x;
    return x + mult(x, y-1);
}


x / 1 = x
x / n = (x - n) / (n - 1)

100 / 10 = ( 100 - 10) / (10 - 1)


int sum(int a[], int capacity)
{
    int total = 0;
    for(int i = 0; i < capacity; i++)
        total += a[i];
    return total;
}

main()
{
    int x[5] = {6, 10, 23, 12, 1};
    cout << sum(x, 5);
}

http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes




using this, write a function to tell me if a number is prime

bool aComposite[1025];

void setupArray()
{

}

bool isPrime(int n)
{
    return ! aComposite[n];
}

bool isPrime(int n)
{
    if (n== 1 || n == 2)
        return true;
    for (int i = 2; i <= n-1; i++)
        if (n % i == 0)
            return false;
    return true;
}

const double hourlyRate = 16.78;
const double ssRate = 0.06;
const double fedRate = 0.14;
const double stateRate = 0.05;
const int unionDues = 10;
const int healthInsurance = 35;

// input: hoursWorked, numDependents
// output: grossPay, withholdingamts, netPay

int main()
{
    cout << "....";
    cin >> hoursWorked >> numDependents;

    double grossPay;
    double netPay;
    double ssTax, fedTax, stateTax, health = 0;
    grossPay = (hoursWorked > 40 ? 40 * hourlyRate + (hoursWorked-40)*
            hourlyRate*1.5 : hoursWorked * hourlyRate);

    if (hoursWorked > 40)
        grossPay = 40 * hourlyRate + (hoursWorked-40)*hourlyRate*1.5;
    else
        grossPay =  hoursWorked * hourlyRate;
   
    ssTax = grossPay * ssRate;
    fedTax = grossPay * fedRate;
    stateTax = grossPay * stateRate;

    if (numDependents >= 3)
        health = healthInsurance;

    netPay = grossPay - ssTax - fedTax - stateTax - health;

    cout <<

}

// input: currentPrice, numYears, inflationRate
// output: futureCost
int main()
{
    double currentPrice, inflationRate, futureCost;
    int numYears;
    cout << ...
    cin >> currentPrice >> numYears >> inflationRate;
    inflationRate /= 100;

    futureCost = currentPrice;

   
    for(int i = 0; i < numYears; i++)
        futureCost = futureCost + futureCost * inflationRate;

    cout << futureCost;

}

int main()
{
    cout << "Please enter 10 numbers";
    int n, sumPositive, sumNegative;

    sumPositive = sumNegative = 0;

    for (int i = 1; i <= 10; i++)
    {
        cin >> n;
        if (n > 0)
            sumPositive += n;
        else
            sumNegative += n;
    }
    cout << sumPositive << " " << sumNegative << " " << sumPositive + sumNegative << endl;
}



int main()
{
    cout << ...;
    double n;
    cin >> n;

    // compute sqrt(n)
   
    double guess = n / 2;
    double r;
do
{
    r = n / guess;
    prevGuess = guess;
    guess = (guess + r) / 2;
} while (abs(guess - prevGuess) > 0.01);


}

end of ch exercises

Click on the image to see even what is presently cut off.

// dfgdfdfg.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

//DISPLAY 3.4 The Importance of Braces

//Illustrates the importance of using braces in if-else statements.

#include
using namespace std;

enum month { Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sept, Oct, Nov, Dec};
//Program to illustrate the switch statement.

#include

using namespace std;
int main( )
{
    month myMonth;
    myMonth = Jan;
    if (myMonth == Mar)
   char grade;
   cout << "Enter your midterm grade and press Return: ";
   cin >> grade;

   if (grade == 'A')
   {
       cout << "Excellent. "
                << "You need not take the final.\n";
   }
   else if (grade  == 'B')
   {
           cout << "Very good. ";
           grade = 'A';
           cout << "Your midterm grade is now "
                << grade << endl;
   }
   else if (grade == 'C')
   {

   }
   else if ()
   {
   }
   else
   {
   }

   switch (grade)
   {
       case 'A':
           cout << "Excellent. "
                << "You need not take the final.\n";
           break;
       case 'B':
           cout << "Very good. ";
           grade = 'A';
           cout << "Your midterm grade is now "
                << grade << endl;
           break;
       case 'C':
           cout << "Passing.\n";
           break;
       case 'D':
       case 'F':
           cout << "Not good. "
                << "Go study.\n";
           break;
       default:
           cout << "That is not a possible grade.\n";
   }

   cout << "End of program.\n";
   return 0;

}