A help program that uses a disk file to store help information

  
/*
C# A Beginner's Guide
By Schildt

Publisher: Osborne McGraw-Hill
ISBN: 0072133295
*/

/*   
   Project 11-2   
   
   A help program that uses a disk file 
   to store help information. 
*/   
 
using System; 
using System.IO;  
 
/* The Help class opens a help file, 
   searches for a topic, and then displays 
   the information associated with that topic. */  
class Help { 
  string helpfile; // name of help file 
 
  public Help(string fname) { 
    helpfile = fname; 
  } 
 
  // Display help on a topic. 
  public bool helpon(string what) {  
    StreamReader helpRdr; 
    int ch; 
    string topic, info; 
 
    try { 
      helpRdr = new StreamReader(helpfile); 
    } 
    catch(FileNotFoundException exc) { 
      Console.WriteLine(exc.Message); 
      return false; 
    } 
 
    try { 
      do { 
        // read characters until a # is found 
        ch = helpRdr.Read(); 
 
        // now, see if topics match 
        if(ch == '#') { 
          topic = helpRdr.ReadLine(); 
          if(what == topic) { // found topic 
            do { 
              info = helpRdr.ReadLine(); 
              if(info != null) Console.WriteLine(info); 
            } while((info != null) && (info != "")); 
            helpRdr.Close(); 
            return true; 
          } 
        } 
      } while(ch != -1); 
    } 
    catch(IOException exc) { 
      Console.WriteLine(exc.Message); 
    }  
    helpRdr.Close(); 
    return false; // topic not found 
  }  
  
  // Get a Help topic. 
  public string getSelection() {  
    string topic = ""; 
 
    Console.Write("Enter topic: ");   
    try {   
      topic = Console.ReadLine(); 
    } 
    catch(IOException exc) { 
      Console.WriteLine(exc.Message); 
      return ""; 
    } 
    return topic; 
  } 
}  
  
// Demonstrate the file-based Help system. 
public class FileHelp {   
  public static void Main() {   
    Help hlpobj = new Help("helpfile.txt");  
    string topic; 
 
    Console.WriteLine("Try the help system. " + 
                       "Enter 'stop' to end.");  
    do {  
      topic = hlpobj.getSelection();   
 
      if(!hlpobj.helpon(topic)) 
        Console.WriteLine("Topic not found.\n"); 
 
    } while(topic != "stop"); 
  }  
}

/*
#if
if(condition) statement;
else statement;

#switch
switch(expression) {
  case constant:
    statement sequence  
    break;  
    // ...  
  }  

#for
for(init; condition; iteration) statement;  

#while
while(condition) statement;  

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

#break
break; or break label;  

#continue
continue; or continue label;  

#goto
goto label;
 
*/

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A help program that uses a disk file to store help information : Stream Read Write « File Stream « C# / C Sharp

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