Strings
// This program demonstrates string functions.
using System;
class Strings
{
public static void Main (string[] args)
{
String str = "Hello";
Console.WriteLine("string: " + str);
Console.WriteLine("string.ToLower(): " + str.ToLower());
Console.WriteLine("string.ToUpper(): " + str.ToUpper());
Console.WriteLine("string.IndexOf('e'): " + str.IndexOf('e'));
Console.WriteLine("string.Length: " + str.Length);
Console.WriteLine("string.Replace('H', 'j'): " + str.Replace('H', 'j'));
Console.WriteLine("string(Substring(2, 2)): " + str.Substring(2, 2));
Console.WriteLine("string.Trim(): " + str.Trim());
String name = "Bob";
double value = 123.456;
Console.WriteLine(String.Format("{0} earned {1:$0.00}", name, value));
}
}
Output
string: Hello
string.ToLower(): hello
string.ToUpper(): HELLO
string.IndexOf('e'): 1
string.Length: 5
string.Replace('H', 'j'): jello
string(Substring(2, 2)): ll
string.Trim(): Hello
Bob earned $123.46
Files
// This program creates a file, adds data to the file, displays the file,
// appends more data to the file, displays the file, and then deletes the file.
// It will not run if the file already exists.
//
// References:
// https://www.mathsisfun.com/temperature-conversion.html
// https://en.wikibooks.org/wiki/C_Sharp_Programming
using System;
public class Files
{
public static void Main(String[] args)
{
string FILENAME = "~file.txt";
if(System.IO.File.Exists(FILENAME))
{
System.Console.WriteLine("File already exists.\n");
}
else
{
CreateFile(FILENAME);
ReadFile(FILENAME);
AppendFile(FILENAME);
ReadFile(FILENAME);
DeleteFile(FILENAME);
}
}
private static double CalculateFahrenheit(double celsius)
{
double fahrenheit;
fahrenheit = celsius * 9 / 5 + 32;
return fahrenheit;
}
private static void CreateFile(string filename)
{
System.IO.StreamWriter file;
double celsius;
double fahrenheit;
try
{
file = System.IO.File.CreateText(filename);
file.WriteLine("Celsius,Fahrenheit");
for(celsius = 0; celsius <= 50; celsius++)
{
fahrenheit = CalculateFahrenheit(celsius);
file.WriteLine(String.Format("{0:F1},{1:F1}", celsius, fahrenheit));
}
file.Close();
}
catch(Exception exception)
{
Console.WriteLine("Error creating " + filename);
Console.WriteLine(exception.Message);
}
}
private static void ReadFile(string filename)
{
System.IO.StreamReader file;
string line;
try
{
file = System.IO.File.OpenText(filename);
while (true)
{
line = file.ReadLine();
if (line == null)
{
break;
}
Console.WriteLine(line);
}
file.Close();
Console.WriteLine("");
}
catch(Exception exception)
{
Console.WriteLine("Error reading " + filename);
Console.WriteLine(exception.Message);
}
}
private static void AppendFile(string filename)
{
System.IO.StreamWriter file;
double celsius;
double fahrenheit;
try
{
file = System.IO.File.AppendText(filename);
for(celsius = 51; celsius <= 100; celsius++)
{
fahrenheit = CalculateFahrenheit(celsius);
file.WriteLine(String.Format("{0:F1},{1:F1}", celsius, fahrenheit));
}
file.Close();
}
catch(Exception exception)
{
Console.WriteLine("Error appending to " + filename);
Console.WriteLine(exception.Message);
}
}
private static void DeleteFile(string filename)
{
try
{
System.IO.File.Delete(filename);
}
catch(Exception exception)
{
Console.WriteLine("Error deleting " + filename);
Console.WriteLine(exception.Message);
}
}
}
Output
Celsius,Fahrenheit
0.0,32.0
1.0,33.8
2.0,35.6
...
98.0,208.4
99.0,210.2
100.0,212.0