Sample Programs:
For those who have difficulty to start writing C++ programs, here are 9 sample programs, which progressively introduce various elementary concepts in C++. Go through these sample codes, type them up, compile and run them on the Visual C++ development environment. These exercises will give you enough confidence to proceed with Project 1
Example 1
// This is a comment line
// My first C++ program
#include <iostream.h> // Compiler directive
int main() // Function header
{
cout << "Hello World!!" << endl;
cout << "This is my first C++ program output" << endl;
return 0;
}
Example 2
// This program deals with variable declarations
#include <iostream.h>
int main()
{
int count,employee_id = 1024; // integer variables
double gross_pay = 2000.0, net_pay; // real variables
char employee_code ='P', union_code; // char variables
const float tax_rate =0.25; // named constant
cout << "The employee ID is: " << employee_id << endl;
cout << "The gross pay is: " << gross_pay << endl;
cout << "The employee code is :" << employee_code << endl;
return 0;
}
Example 3
// This program demonstrates the use of the assignment
// operator
#include <iostream.h>
int main()
{
int num1, num2 = 6;
double weight;
char letter;
num1 = 5; // Assigns 5 to num1
weight = 25.7; // Assigns 25.7 to weight
letter = 'A'; // Assigns A to letter
num1 = num1 + 5; // New value of num1 is 10
num2 = num1 + num2; // New value of num2 is 16
weight = 2 * weight + 3.0; // New value of weight
// is 54.4
letter = letter + 1; // New value of letter is B
cout << "The package number is: " << num2 << endl;
cout << "The package type is: " << letter << endl;
cout << "The package weight is: " << weight << endl;
return 0;
}
Example 4
// Finding the values of the standard named constants
#include <stdlib.h>
#include <float.h>
#include <limits.h>
#include <iostream.h>
int main()
{
cout << "Success code = " << EXIT_SUCCESS << endl;
cout << "Failure code = " << EXIT_FAILURE << endl;
cout << "Smallest integer = " << INT_MIN << endl;
cout << "Largest integer = " << INT_MAX << endl;
cout << "Smallest long integer = " << LONG_MIN << endl;
cout << "Largest long integer = " << LONG_MAX << endl;
cout << "Smallest float type number = " << FLT_MIN << endl;
cout << "Largest float type number = " << FLT_MAX << endl;
cout << "Smallest double type number = " << DBL_MIN << endl;
cout << "Largest double type number = " << DBL_MAX << endl;
return 0;
}
Example 5
// Increment and decrement operators
// Verify the results by hand calculation
#include <iostream.h>
int main()
{
int i=3, k=5, j=8, m=2;
cout <<" m i j k"<<endl;
cout <<" ----------------"<<endl;
m = ++ i * k --;
cout << " " << m << " "<< i << " "
<< j <<" "<< k << endl;
m = j ++ * k --;
cout << " " << m << " "<< i << " "
<< j <<" "<< k << endl;
m = j ++ * ++ k;
cout << " " << m << " "<< i << " "
<< j <<" "<< k << endl;
m = -- i * -- k;
cout << " " << m << " "<< i << " "
<< j <<" "<< k << endl;
m = -- j * k ++;
cout << " " << m << " "<< i << " "
<< j <<" "<< k << endl;
return 0;
}
Example 6
// This program deals with arithmetic expressions
// Check the results by hand calculation
#include <iostream.h>
int main()
{
int i = 5, j = 3, m;
double x = 10.0, y = 7.0;
m = i/j; // integer division
cout << m << endl;
m = i%j; // remainder operation
cout << m << endl;
m = i%j*4 + y/3;
cout << m << endl;
m = i*x/2 + i/3.0;
cout << m << endl;
x = i/j + 2*y;
cout << x << endl;
y = y*x + (j+5)%3;
cout << y << endl;
return 0;
}
Example 7
// Input from keyboard
// Use of cin statement
// This program calculates the average of three numbers
#include <iostream.h>
int main()
{
double number1, number2, number3;
double average;
cout << "Enter any three numbers separated by space: ";
cin >> number1 >> number2 >> number3;
average = (number1 + number2 + number3)/3;
cout << "The average is :" << average << endl;
return 0;
}
Example 8
// This program shows how to invoke a library function
// Check each result by hand calculation
#include <iostream.h>
#include <math.h>
int main()
{
double x = 25.0;
double result;
result = sqrt(x); // invokes square root function
cout <<"The square root of "<< x << " = " << result <<endl;
result = sqrt(2*x + 5);
cout << "The result of the first expression is "
<< result << endl;
result = 20.0 + sqrt(2*x + sqrt(x));
cout <<"The result of the second expression is "
<< result << endl;
return 0;
}
Example 9
// This program demonstrates file I/Os and I/O manipulators
// This program takes data from an input file "salary.dat"
// containing the employee number and the annual salary of each
// employee in an organization and compute the biweekly gross pay,
// the federal tax, the state tax, the social security tax,
// the medicare tax, and the net_pay for each employee. The results
// are saved in a file "pay.dat".
#include <iomanip.h> // For manipulating widths and precisions
#include <fstream.h> // For file I/O
// Hypothetical tax rates, defined as constants
const float FED_TAX_RATE = 0.15;
const float STATE_TAX_RATE = 0.05;
const float SS_TAX_RATE = 0.08;
const float MED_TAX_RATE = 0.01;
int main()
{
ofstream pay_file; // declare output file stream pay_file
ifstream salary_file; // declare input file stream salary_file
int employee_number;
double annual_salary;
double gross_pay, fed_tax, state_tax, ss_tax, med_tax, net_pay;
pay_file.setf(ios::fixed, ios::floatfield); // Setup floating point
pay_file.setf(ios::showpoint); // output format
pay_file.open("a:pay.dat"); // open files "a:pay.dat"
salary_file.open("a:salary.dat"); // and "a:salary.dat" and
// link them with the
// coresponding file streams
// Read the first set of data (*** prime read operation)
salary_file >> employee_number >> annual_salary;
// process all statements enclosed in braces (the compound statement)
// again and again while the input file stream salary_file has
// some data to be extracted. That is, process until to the end of
// file "a:salary.dat"
while (salary_file)
{
gross_pay = annual_salary / 24;
fed_tax = FED_TAX_RATE * gross_pay;
state_tax = STATE_TAX_RATE * gross_pay;
ss_tax = SS_TAX_RATE * gross_pay;
med_tax = MED_TAX_RATE * gross_pay;
net_pay = gross_pay -(fed_tax + state_tax + ss_tax + med_tax);
// output results with 10 positions
// output floating point results with two decimals
pay_file << setw(10) << employee_number
<< setw(10) << setprecision(2) << gross_pay
<< setw(10) << setprecision(2) << fed_tax
<< setw(10) << setprecision(2) << state_tax
<< setw(10) << setprecision(2) << ss_tax
<< setw(10) << setprecision(2) << med_tax
<< setw(10) << setprecision(2) << net_pay << endl;
// read next data set
salary_file >> employee_number >> annual_salary;
}
salary_file.close();
pay_file.close();
return 0;
}