Code Doppler Programming Tutorials: Welcome to Codedoppler

Code Doppler Programming Tutorials: Welcome to Codedoppler: Code Doppler is a newborn community for newbie to professional developers in JAVA and C++ programming languages. Our purpose is to prov...

C++ Loops

The purpose of loops is to repeat the execution of codes a number of time while the condition is still true.

while loop:
 The form:

while(condition)
{
    statement(s);
}

do while loop:
The form:

do
{
    statement(s);
}while(condition);

The difference of the do while is that, it will first execute the statements first then check if the condition is still true then if it is still true, it will iterate or loop (executes the statement(s) again).

for loop:
The form:
for (initialization; condition; increment/decrement)
{
    statement(s);
}


Examples:

int x=10;
int i = 0;
while (i<x)
{
    cout<<i<<": Hi"<<endl;
    i++;
}

do
{
    cout<<i<<": Hi"<<endl;   
    i++;
}while(i<x)

for (int a=0;a<10;a++)
{
     cout<<a<<": Hi"<<endl;
}

Try it and see the difference.

switch case statements

Switch case statements do a similar job like if else statements. The form is:

switch (variable)
{
    case value1:
        statement(s);
        break;
    case value2:
        statement(s);
        break;
    default:
        break;
}

Example:
int x = 0;
switch (x)
{
    case 0:
        cout<<"X is 0"<<endl; //you can have like this code for newline
        break;
    case 1:
        cout<<"X is 1";
        cout<<endl; //or you can separate like this.
        break;
    default:
        cout<<"X is neither 0 nor 1";
        break;
}

Remember that you can have multiple numbers of case statements not just two like the above example.

Next: C++ Loops

if, if else

if:

if statement is used to execute a code or a series of codes if and only if the condition is met. The form is:

if (condition)
     statement;

The condition is the expression that is being evaluated. If it is true, statement is executed. If it is false, statement is not executed.

If you want to execute a series of statements/codes, you should use curly braces { }. The form is:

if (condition)
{
    statements;
    statements;
}

Examples:

int x=0;

if (x==0)
    cout<<"X is "<<x<<endl;

if (x==1)
    cout<<"X is 1";
cout <<"X is not 1";

if (x==0)
{
    cout<<"X is 0";
    cout<<"X is not 1";
}


if else:
if else control structure is very similar to if statements. We will just add the else keyword if the condition is false. The form is:

if (condition)
    statement;
else
    statement;

If the condition is false, the statement in the else will be executed. Again, if you want to execute a series of statements/codes, you should use curly braces { }.

Example:

int x = 0;

if ( x==1)
    cout<<"X is 1";
else
    cout<<"X is not 1";

Next: switch case statements

C++ Variables

Variables are memory locations where you will store a data. There are several data types a variable can contain. Among the following in C++ are: int, char, float, double and bool.
int - are for integer data types. It is used to contain whole number integers.
char - are for characters. You will see examples later.
float - for integers with decimals.
double - for integers with decimals.
bool - for boolean. True or False;

To declare a variable in C++, this is the format: data_type name
int x;
float y;
bool tf;

You can also declare multiple variables with the same data type:
int x,y,z;


The name of the variable is case sensitive. Var1 is different from var1.

To Initialize a variable:
int x=0;

or declare then initialize:
int x;
x=0;

Next: if, if else statements

Quick Sort in JAVA

Quick Sort is one of the fastest sorting algorithms.
Here is the code snippet for Java.


public static int divide(int array[], int left, int right)
    {
        int i = left, j = right;
        int tmp;
        int pivot = array[(left + right) / 2];
       
        while (i <= j) {
            while (array[i] < pivot)
                i++;
            while (array[j] > pivot)
                j--;
            if (i <= j) {
                tmp = array[i];
                array[i] = array[j];
                array[j] = tmp;
                i++;
                j--;
            }
        }
        return i;
    }
    public static void q_srt(int arr[], int left, int right) {
        int i = divide(arr, left, right);
        if (left < i - 1)
            q_srt(arr, left, i - 1);
        if (i < right)
            q_srt(arr, i, right);
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        int []sample = {13,21,36,0,32,54,1,3};
        for(int x=0;x<sample.length;x++){
            System.out.print(sample[x]+":");
        }
        System.out.println("\n-=Sorted Array=-");
        q_srt(sample,0,7);
        for(int x=0;x<sample.length;x++){
            System.out.print(sample[x]+":");
        }
    }

Methods to read excel files in C#

Useful C# methods in order to read cell values in excel.
Remember to add a .NET reference for Microsoft.Office.Interop.Excel and use it in your program via the statement using Microsoft.Office.Interop.Excel;

private static Microsoft.Office.Interop.Excel.ApplicationClass appExcel;
private static Workbook newWorkbook = null;
private static _Worksheet objsheet = null;

Method to initialize excel connection:
        static void excel_init(String path)
        {
            appExcel = new Microsoft.Office.Interop.Excel.ApplicationClass();

            if (System.IO.File.Exists(path))
            {
                // then go and load this into excel
                newWorkbook = appExcel.Workbooks.Open(path, true, true);
                objsheet = (_Worksheet)appExcel.ActiveWorkbook.ActiveSheet;
            }
            else
            {
                MessageBox.Show("Unable to open file!");
                System.Runtime.InteropServices.Marshal.ReleaseComObject(appExcel);
                appExcel = null;
                System.Windows.Forms.Application.Exit();
            }
           
        }

Method to read a cell's value:
        static string excel_getValue(string cellname)
        {
            string value = string.Empty;
            try
            {
                value = objsheet.get_Range(cellname).get_Value().ToString();
            }
            catch
            {
                value = "";
            }

            return value;
        }

Method to safely close excel connection:
        static void excel_close()
        {
            if (appExcel != null)
            {
                try
                {
                    newWorkbook.Close();
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(appExcel);
                    appExcel = null;
                    objsheet = null;
                }
                catch (Exception ex)
                {
                    appExcel = null;
                    MessageBox.Show("Unable to release the Object " + ex.ToString());
                }
                finally
                {
                    GC.Collect();
                }
            }
        }

To use it in your program, you need to initialize the excel connection first via this method:
excel_init(Path_to_your_excel_file);
make sure that your slash \ are double slashes \\. E.g. C:\\excel_file.xls

To read a cell value:
excel_getValue("A1"); this will return the value of the cell.

Safely close the connection with
excel_close(); to prevent memory problems.

Thanks for reading! I hope you gain additional knowledge.

If you have questions and or problems using it, please comment on this article.

Thanks,
Administrator