Csharp/C Sharp/Development Class/Console Input Output

A simple command line program that reads from the console using Console.Read() and Console.ReadLine()

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
/*
    read.cs. A simple command line program that reads from
    the console using Console.Read() and Console.ReadLine().
    Compile this program using the following line:
        C:>csc read.cs
 */
using System;
public class ReadCmdLine
{
    static void Main()
    {
        Console.WriteLine ("First, using the Read() function " +
                           "without clearing the buffer");
        int arg;
        Console.Write("Type one or more characters: ");
        while ((arg = Console.Read()) > 10)
        {
            if (arg == 13)
                Console.WriteLine (" <EOL>");
            else
                Console.Write (Convert.ToChar(arg));
        }
        Console.WriteLine();
        Console.WriteLine ("Now, using the Read() function and " +
                           "clearing the buffer");
        Console.Write("Type one or more characters: ");
        arg = Console.Read ();
        string str = Console.ReadLine();
        Console.WriteLine ("The character is " + Convert.ToChar(arg));
    }
}

C# Basic Data Types

using System;
public class BasicDataTypes
{
    public static void Main(string[] args)
    {
        Console.WriteLine("Value is: {0}", 3);
    }
}

C# Hello Universe

using System;
public class HelloDealWithCommandLineInput
{
    public static void Main(string[] args)
    {
        Console.WriteLine("Hello, Universe");
        
        // iterate over command-line arguments, and print them out
        for (int arg = 0; arg < args.Length; arg++)
        Console.WriteLine("Arg {0}: {1}", arg, args[arg]);
    }
}

Console command-line arguments

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
 
using System; 
 
public class CLDemo {  
  public static void Main(string[] args) { 
    Console.WriteLine("There are " + args.Length + 
                       " command-line arguments."); 
 
    Console.WriteLine("They are: "); 
    for(int i=0; i<args.Length; i++)  
      Console.WriteLine(args[i]);  
  }  
}

constructs sentences by concatenating user input until the user enters one of the termination characters

 
using System;
public class MainClass {
    public static void Main(string[] args) {
        string sSentence = "";
        for (; ; ) {
            Console.WriteLine("Enter a string");
            string sLine = Console.ReadLine();
            if (IsTerminateString(sLine)) {
                break;
            }
            sSentence = String.Concat(sSentence, sLine);
            Console.WriteLine("\nYou"ve entered: {0}", sSentence);
        }
    }
    public static bool IsTerminateString(string source) {
        string[] sTerms = {"EXIT","exit","QUIT","quit"};
        foreach (string sTerm in sTerms) {
            if (String.rupare(source, sTerm) == 0) {
                return true;
            }
        }
        return false;
    }
}

Convert input from control to upper case

 
using System;
public class MainClass {
    static void Main() {
        Console.WriteLine("Enter command:");
        string resp = (Console.ReadLine()).ToLower();
        switch (resp) {
            case "a":
                Console.WriteLine("Doing Task A");
                break;
            case "b":
                Console.WriteLine("Doing Task B");
                break;
            case "c":
                Console.WriteLine("Doing Task C");
                break;
            default:
                Console.WriteLine("Bad choice");
                break;
        }
    }
}

Demonstrates redirecting the Console output to a file

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
// Redirect.cs -- Demonstrates redirecting the Console output to a file
//
//                Compile this program with the following command line:
//                    C:>csc Redirect.cs
//
using System;
using System.IO;
namespace nsStreams
{
    public class Redirect
    {
        static public void Main ()
        {
            FileStream ostrm;
            StreamWriter writer;
            TextWriter oldOut = Console.Out;
            try
            {
                ostrm = new FileStream ("./Redirect.txt", FileMode.OpenOrCreate, FileAccess.Write);
                writer = new StreamWriter (ostrm);
            }
            catch (Exception e)
            {
                Console.WriteLine ("Cannot open Redirect.txt for writing");
                Console.WriteLine (e.Message);
                return;
            }
            Console.SetOut (writer);
            Console.WriteLine ("This is a line of text");
            Console.WriteLine ("Everything written to Console.Write() or");
            Console.WriteLine ("Console.WriteLine() will be written to a file");
            Console.SetOut (oldOut);
            writer.Close();
            ostrm.Close();
            Console.WriteLine ("Done");
        }
    }
}

Demonstrates some of the formatting flags for writing text to the console

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
/*
    Format.cs. Demonstrates some of the formatting flags for writing text
               to the console.
               Compile this program with the following command line:
                   C:>csc format.cs
*/
namespace nsFormat
{
    using System;
    public class Format
    {
        static readonly double e = 2.71828;
        static void Main()
        {
            Console.WriteLine ("Integer dollar amount: {0,0:C}", 3);
            Console.WriteLine ("Floating dollar amount: {0,0:C}", 3.29);
            Console.WriteLine ("Integer value: {0,0:D5}", 1024);
            Console.WriteLine ("Integer value: {0,0:N5}", 1024742);
            Console.WriteLine ("Integer value: {0,0:N}", 1024742);
            Console.WriteLine ("Integer value: {0,0:N5}", 1024742);
            Console.WriteLine ("Integer value: {0,0:X}", 1024742);
            Console.WriteLine ("Floating point e: {0,0:F3}", e);
            Console.WriteLine ("Floating point e: {0,-8:F5}", e);
            Console.WriteLine ("Floating point e: {0,-8:E2}", e);
            Console.WriteLine ("Floating point e: {0,-8:E}", e);
        }
    }
}

Demonstrate various format specifiers

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/

// Demonstrate various format specifiers. 
  
using System;  
  
public class FormatDemo {  
  public static void Main() {  
    double v = 17688.65849;  
    double v2 = 0.15;  
    int x = 21;  
   
    Console.WriteLine("{0:F2}", v);  
  
    Console.WriteLine("{0:N5}", v);  
  
    Console.WriteLine("{0:e}", v);  
  
    Console.WriteLine("{0:r}", v);  
  
    Console.WriteLine("{0:p}", v2);  
  
    Console.WriteLine("{0:X}", x);  
  
    Console.WriteLine("{0:D12}", x);  
 
    Console.WriteLine("{0:C}", 189.99);  
  }  
}

Illustrates how to read a character entered using the keyboard

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
  Example2_13.cs illustrates how to read
  a character entered using the keyboard
*/
public class Example2_131
{
  public static void Main()
  {
    System.Console.Write("Enter a character: ");
    char myChar = (char) System.Console.Read();
    System.Console.WriteLine("You entered " + myChar);
  }
}

Illustrates how to read a string entered using the keyboard

/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
  Example2_14.cs illustrates how to
  read a string entered using the keyboard
*/
public class Example2_141
{
  public static void Main()
  {
    System.Console.Write("Enter a string: ");
    string myString = System.Console.ReadLine();
    System.Console.WriteLine("You entered " + myString);
  }
}

input a series of numbers separated by commas, parse them into integers and output the sum

 
using System;
class Class1 {
    public static void Main(string[] args) {
        Console.WriteLine("Input a series of numbers separated by commas:");
        string input = Console.ReadLine();
        char[] cDividers = { ",", " " };
        string[] segments = input.Split(cDividers);
        int nSum = 0;
        foreach (string s in segments) {
            if (s.Length > 0) {
                if (IsAllDigits(s)) {
                    int num = Int32.Parse(s);
                    Console.WriteLine("Next number = {0}", num);
                    nSum += num;
                }
            }
        }
        Console.WriteLine("Sum = {0}", nSum);
    }
    public static bool IsAllDigits(string sRaw) {
        string s = sRaw.Trim();
        if (s.Length == 0) {
            return false;
        }
        for (int index = 0; index < s.Length; index++) {
            if (Char.IsDigit(s[index]) == false) {
                return false;
            }
        }
        return true;
    }
}

Input from the console using ReadLine()

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Input from the console using ReadLine(). 
 
using System;  
  
public class ReadString { 
  public static void Main() { 
    string str; 
 
    Console.WriteLine("Enter some characters."); 
    str = Console.ReadLine(); 
    Console.WriteLine("You entered: " + str); 
  } 
}

Output with parameters

/*
Learning C# 
by Jesse Liberty
Publisher: O"Reilly 
ISBN: 0596003765
*/
public class AssignedValues {
    static void Main( )
    {
       int myInt;
       //other code here...
       myInt = 7;  // assign to it
       System.Console.WriteLine("Assigned, myInt: {0}", myInt);
       myInt = 5;
       System.Console.WriteLine("Reassigned, myInt: {0}", myInt);
    }
 }

Read a character from the keyboard

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Read a character from the keyboard. 
 
using System; 
 
public class KbIn {   
  public static void Main() { 
    char ch; 
 
    Console.Write("Press a key followed by ENTER: "); 
 
    ch = (char) Console.Read(); // get a char 
    
    Console.WriteLine("Your key is: " + ch); 
  }   
}

Read a line from console

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
// dbTest.cs -- Sample program to be used with cordbg.exe
//
//              Compile this program with the following command line:
//                  C:>csc /debug:full dbTest.cs
//
using System;
namespace nsDebug
{
    public class dbTest
    {
        static public void Main ()
        {
            double x = 7.0;
            while (true)
            {
                Console.Write ("\r\nPlease enter a number: ");
                string str = Console.ReadLine ();
                if (str.Length == 0)
                    break;
                double val = 0;
                try
                {
                    val = Convert.ToDouble (str);
                }
                catch (Exception)
                {
                    Console.WriteLine ("\r\nInvalid number");
                    continue;
                }
                Console.WriteLine (x + " X " + val + " = {0,0:F6}", val / x);
            }
        }
    }
}

Read a string from the keyboard, using Console.In directly

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Read a string from the keyboard, using Console.In directly.  
 
using System;  
 
public class ReadChars2 { 
  public static void Main() { 
    string str; 
 
    Console.WriteLine("Enter some characters."); 
 
    str = Console.In.ReadLine(); 
 
    Console.WriteLine("You entered: " + str); 
  } 
}

Read double and int from console

 
using System;
using System.Collections.Generic;
using System.Text;
class Program {
    static void Main(string[] args) {
        (new Program()).run();
    }
    public void run() {
        double dailyRate = readDouble("Enter your daily rate: ");
        int noOfDays = readInt("Enter the number of days: ");
        writeFee(calculateFee(dailyRate, noOfDays));
    }
    private void writeFee(double p) {
        Console.WriteLine("The consultant"s fee is: {0}", p * 1.1);
    }
    private double calculateFee(double dailyRate, int noOfDays) {
        return dailyRate * noOfDays;
    }
    private int readInt(string p) {
        Console.Write(p);
        string line = Console.ReadLine();
        return int.Parse(line);
    }
    private double readDouble(string p) {
        Console.Write(p);
        string line = Console.ReadLine();
        return double.Parse(line);
    }
}

Redirect Console.Out

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Redirect Console.Out. 
 
using System;  
using System.IO; 
  
public class Redirect { 
  public static void Main() { 
    StreamWriter log_out; 
 
    try { 
      log_out = new StreamWriter("logfile.txt"); 
    } 
    catch(IOException exc) { 
      Console.WriteLine(exc.Message + "Cannot open file."); 
      return ; 
    } 
    
    // Direct standard output to the log file. 
    Console.SetOut(log_out); 
    Console.WriteLine("This is the start of the log file."); 
 
    for(int i=0; i<10; i++) Console.WriteLine(i); 
 
    Console.WriteLine("This is the end of the log file."); 
    log_out.Close(); 
  } 
}

Terminate a control input

 
using System;
public class MainClass {
    static void Main() {
        string resp;
        Console.WriteLine("Enter command ("x" to end):");
        while ((resp = (Console.ReadLine()).ToLower()) != "x") {
            switch (resp) {
                case "a":
                    Console.WriteLine("Doing Task A");
                    break;
                case "b":
                    Console.WriteLine("Doing Task B");
                    break;
                default:
                    Console.WriteLine("Bad choice");
                    break;
            }
        }
    }
}

This program averages a list of numbers entered by the user

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// This program averages a list of numbers entered by the user.  
  
using System; 
using System.IO;  
  
public class AvgNums {  
  public static void Main() {  
    string str;  
    int n;  
    double sum = 0.0; 
    double avg, t;  
      
    Console.Write("How many numbers will you enter: ");  
    str = Console.ReadLine(); 
    try { 
      n = Int32.Parse(str); 
    }  
    catch(FormatException exc) { 
      Console.WriteLine(exc.Message); 
      n = 0; 
    } 
    catch(OverflowException exc) { 
      Console.WriteLine(exc.Message); 
      n = 0; 
    } 
    
    Console.WriteLine("Enter " + n + " values."); 
    for(int i=0; i < n ; i++)  {  
      Console.Write(": "); 
      str = Console.ReadLine();  
      try {  
        t = Double.Parse(str);  
      } catch(FormatException exc) {  
        Console.WriteLine(exc.Message);  
        t = 0.0;  
      }  
      catch(OverflowException exc) { 
        Console.WriteLine(exc.Message); 
        t = 0; 
      } 
      sum += t;  
    }  
    avg = sum / n; 
    Console.WriteLine("Average is " + avg); 
  }  
}

Use do while to read console input

 
using System;
public class MainClass {
    static void Main() {
        string resp;
        do {
            Console.WriteLine("Menu\n\n1 - Task A");
            Console.WriteLine("2 - Task B");
            Console.WriteLine("E - E(xit)");
            resp = (Console.ReadLine()).ToLower();
        }
        while (resp != "e");
    }
}

Use format commands

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Use format commands.  
 
using System; 
 
public class DisplayOptions {    
  public static void Main() {    
    int i; 
 
    Console.WriteLine("Value\tSquared\tCubed"); 
 
    for(i = 1; i < 10; i++) 
      Console.WriteLine("{0}\t{1}\t{2}",  
                        i, i*i, i*i*i); 
  }    
}

Uses the #, 0 and comma characters to format output

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
/*
    Picture.cs.  Uses the #, 0 and comma characters to format output
*/
using System;
public class Picture
{
    static void Main()
    {
        Console.WriteLine ("Using the # character");
        Console.WriteLine ("\tInteger dollar amount: {0,0:$###.##}", 3);
        Console.WriteLine ("\tFloating dollar amount: {0,0:$###.##}", 3.29);
        Console.WriteLine ("\tInteger value: {0,0:###,###}",1428);
        Console.WriteLine ("\tFloating point value: {0,0:#,###.#####}", 1428.571);
        Console.WriteLine ("Using the $ character");
        Console.WriteLine ("\tInteger dollar amount: {0,0:$000.00}", 3);
        Console.WriteLine ("\tFloating dollar amount: {0,0:$000.00}", 3.29);
        Console.WriteLine ("Using the comma alone");
        Console.WriteLine ("\tInteger value: {0,0:000,000}", 1428);
        Console.WriteLine ("\tFloating point value: {0,0:0,000.000}", 1428.571);
    }
}

Use while(true) to read console input

 
using System;
public class MainClass {
    static void Main() {
        string resp;
        while (true) {
            Console.WriteLine("Menu\n\n1 - Task A");
            Console.WriteLine("2 - Task B");
            Console.WriteLine("E - E(xit)");
            resp = (Console.ReadLine()).ToLower();
            if (resp == "e") {
                break;
            }
        }
    }
}

While loop and keyboard reading

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
namespace nsLoops
{
    using System;
    
    public class Loops
    {
        static public void Main ()
        {
            int [] arr = new int [5];
            for (int x = 0; x < arr.Length; ++x)
            {
                bool done = false;
                while (!done)
                {
                    Console.Write ("Enter a value for element {0}: ", x);
                    string str = Console.ReadLine ();
                    int val;
                    try
                    {
                        val = int.Parse (str);
                    }
                    catch (FormatException)
                    {
                        Console.WriteLine ("Please enter an integer value\r\n");
                        continue;
                    }
                    arr[x] = val;
                    done = true;
                }
            }
            int index = 0;
            foreach (int val in arr)
            {
                Console.WriteLine ("arr[{0}] = {1}", index, val);
                ++index;
            }
        }
    }
}

Write to Console.Out and Console.Error

/*
C#: The Complete Reference 
by Herbert Schildt 
Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Write to Console.Out and Console.Error. 
 
using System; 
 
public class ErrOut { 
  public static void Main() { 
    int a=10, b=0; 
    int result; 
 
    Console.Out.WriteLine("This will generate an exception."); 
    try { 
      result = a / b; // generate an exception 
    } catch(DivideByZeroException exc) { 
      Console.Error.WriteLine(exc.Message); 
    } 
  } 
}