Unlocking Microsoft C# V 2.0 Programming Secrets (Wordware Applications Library)

2017-07-07 02:10:07

Common Conversions

Listed below are the common data conversions you will encounter in programming with the Visual Studio C# compiler. The following examples are in executable form in project DataConversion at Visual Studio 2005\Projects\DemosSourceCode so you can confirm that the data conversions work as advertised.

ANSIString to:
1. Character string:
  
  string strString = "Mary had a little lamb."; charString = strString.ToCharArray(); // Do not attempt to terminate this 'charString' with the null char. // The statement 'charString[strString.Length] = '
  string strString = "Mary had a little lamb."; charString = strString.ToCharArray(); // Do not attempt to terminate this 'charString' with the null char. // The statement 'charString[strString.Length] = '\0'' won't work. '' won't work.
2. Int32 (integer):
  
  // 'strString' must be an integer! No float allowed here. strString = "457"; int intNumber = Convert.ToInt32(strString);
  
  Example:
  
  strTB1 = textBox1.Text; // (data taken from a text box) string strShortYear = strTB1.Substring(2,2); intYear = Convert.ToInt32(strShortYear);
3. Int64 (long):
  
  // 'strNumber' must be a long! No float allowed here. string strNumber = "444444444"; long lgNumber = Convert.ToInt64(strNumber);
4. Double (double-precision floating-point number):
  
  strString = "433.8395"; double dblNumber = Double.Parse(strString);
  
  or
  
  double dblNumber2 = Convert.ToDouble(strString);
5. Decimal (base 10 arithmetic; two digits to right of decimal point):
  
  strString = "445.33"; decimal decNumber = Decimal.Parse(strString); MessageBox.Show("Item #1E-1 response is '" + decNumber.ToString() + "' .");
  
  or
  
  decimal decNumber2 = Convert.ToDecimal(strString);
  
  Example:
  
  dBuyNOS = Decimal.Parse(strNOS); dBuyTP = Decimal.Parse(strTP);

Character string to:
1. ANSIString:
  
  charString = "Mary had a little lamb".ToCharArray(); // Create an example string. strString = new string(charString);
2. Int32 (integer):
  
  // 'charString' must be in integer format for 'Convert.ToInt32' to work. No float. charString = "3376".ToCharArray(); strString = new string(charString); // This next statement works ONLY with 'strString'. Won't work with 'charString'. intNumber = Convert.ToInt32(strString);
  
  or
  
  intNumber = Int32.Parse(strString); // Only 'strString' works -- no 'charString'.
3. Int64 (long):
  
  charString = "3394".ToCharArray(); // This 'strString' must be in integer format. No float. strString = new string(charString); lgNumber = Convert.ToInt64(strString);
  
  or
  
  lgNumber = Int64.Parse(strString); // Only 'strString' works -- no 'charString'.
4. Double (double-precision floating-point number):
  
  strString = "1935.006"; charString = strString.ToCharArray(); // charString[strString.Length] = '
  strString = "1935.006"; charString = strString.ToCharArray(); // charString[strString.Length] = '\0'; Not needed. Terminates the program. strString = new string(charString); dblNumber = Convert.ToDouble(strString); '; Not needed. Terminates the program. strString = new string(charString); dblNumber = Convert.ToDouble(strString);
5. Decimal (base 10 arithmetic; two digits to right of decimal point):
  
  strString = "144.144"; charString = strString.ToCharArray(); //charString[strString.Length] = '
  strString = "144.144"; charString = strString.ToCharArray(); //charString[strString.Length] = '\0'; Not needed. Terminates the program. strString = new string(charString); decNumber = Convert.ToDecimal(strString); '; Not needed. Terminates the program. strString = new string(charString); decNumber = Convert.ToDecimal(strString);

Int32 (integer) to:
1. ANSIString:
  
  intNumber = 565758; strString = Convert.ToString(intNumber);
  
  Example:
  
  string strYearTemp = Convert.ToString(iYear); string strWeekTemp = Convert.ToString(iWeek);
2. Character string:
  
  intNumber = 343536; strString = intNumber.ToString(); charString = strString.ToCharArray();
3. Int64:
  
  intNumber = 7788; lgNumber = (long) intNumber;
4. Double (double-precision floating-point number):
  
  intNumber = 345; double dblNumber9 = Convert.ToDouble(intNumber);
5. Decimal (base 10 arithmetic; two digits to right of decimal point):
  
  intNumber = 722; decimal decNumber17 = Convert.ToDecimal(intNumber);

Int64 (long) to:
1. ANSIString:
  
  lgNumber = 247902; strNumber = lgNumber.ToString();
2. Character string:
  
  lgNumber = 1356992; strNumber = lgNumber.ToString(); charString = strNumber.ToCharArray();
3. Int32:
  
  lgNumber = 456744; intNumber = (int) lgNumber;
4. Double (double-precision floating-point number):
  
  lgNumber = 3478902; double dblNumber14 = (double) lgNumber;
5. Decimal (base 10 arithmetic; two digits to right of decimal point):
  
  long lgNumber3 = 353552; decimal decNumber4 = Convert.ToDecimal(lgNumber3);

Double (double-precision floating-point number) to:
1. ANSIString:
  
  dblNumber = 123456789; strString = Convert.ToString(dblNumber);
2. Character string:
  
  dblNumber = 987654321; strString = Convert.ToString(dblNumber); charString = strString.ToCharArray();
3. Int32:
  
  double dblStart = 74738.22d; int intFinish = (int)dblStart;
4. Int64:
  
  double dblNow = 834.228; long lgLater = (long)dblNow;
5. Decimal (base 10 arithmetic; two digits to right of decimal point):
  
  dblNumber2 = 77.33456d; decNumber = Convert.ToDecimal(dblNumber2); // This conversion (5E) does not currently work!

Decimal (base 10 arithmetic; two digits to right of decimal point) to:
1. ANSIString:
  
  decNumber = 1024.67m; strString = decNumber.ToString();
  
  Example:
  
  // Convert all numbers to 'string' and write them on Form2. strPricePerShare = dPricePerShare.ToString(); strNetNOS = dNetNOS.ToString();
2. Character string:
  
  decNumber = 677.34m; strString = decNumber.ToString(); charString = strString.ToCharArray(); // charString[strString.Length] = '
  decNumber = 677.34m; strString = decNumber.ToString(); charString = strString.ToCharArray(); // charString[strString.Length] = '\0'; Not needed. '; Not needed.
3. Int32:
  
  decimal decRowboat = 1375.22m; int intMerrily = Convert.ToInt32(decRowboat);
  
  or
  
  int intMerrily2 = decRowboat.ToInt32(); // This won't work.
4. Int64:
  
  decimal decRowboat2 = 136.207m; // long lgMerrily3 = decRowboat2.ToInt64(); This scheme won't work!
  
  or
  
  long lgMerrily4 = Convert.ToInt64(decRowboat2); // This works.
5. Double (double-precision floating-point number):
  
  decimal decFlow = 3555.35m; //double dblGently = decFlow.ToDouble(); Won't work.
  
  or
  
  double dblGently2 = Convert.ToDouble(decFlow); // This works.

Char string to integer example:

charString = "3376.44".ToCharArray(); // Convert to a true number, like 'double'. strString = new string(charString); // Convert char to string. dblNumber = Convert.ToDouble(strString); // Convert string to double. // Round the 'double' to NO digits after the decimal point. Math.Round(dblNumber,0); // Round off the double number. // Cast the 'double' to an 'integer'. int intAnswer = (int)dblNumber;

With FileStream (which only reads bytes of data), is there a way I can read blocks of data?

Answers

Yes, once FileStream has opened a file, you can read bytes of data and convert them to chars and later strings. Example:

// Begin file opening with 'FileStream'. FileStream fs; try { fs = new FileStream("KTWeeklyNetWorth.dta", FileMode.OpenOrCreate, FileAccess.ReadWrite); // Read from the file. byte[] byteBlockData = new byte[47]; char[] charBlockData = new char[47]; fs.Read(byteBlockData,0,47); // Convert 'byte' to 'char'. for(int mm = 0; mm < 47; mm++) charBlockData[mm] = Convert.ToChar(byteBlockData[mm]); string strBlockData = new string(charBlockData); MessageBox.Show("BlockData read is '" + strBlockData + "' ."); } catch { MessageBox.Show("Cannot open file 'KTWeeklyNetWorth.dta'."); return; }

If you examine all the conversions shown above, you must conclude that the days of working with character strings are just about over. The ANSIString has every attribute that a character string has, and it keeps track of its length in a subitem named .Length. Below is a list of the queries that can be performed on an ANSIString (a string). Each of these queries returns a bool response, true or false:

Char.IsControl(string str, int Index);

Is the character named in Index a control character?

Char.IsSeparator(string str, int Index);

Is the character named in Index a separator character? (Used in database applications only.)

Char.IsWhiteSpace(string str, int Index);

Is the character named in Index a blank space?

Char.IsPunctuation(string str, int Index);

Is the character a comma, colon , semicolon, period, etc.?

Char.IsSymbol(string str, int Index);

Is the character a symbol (such as the Greek letter alpha)?

Char.IsDigit(string str, int Index);

Is the character between 0 and 9?

Char.IsNumber(string str, int Index);

Is the character between 0 and 9?

Char.IsLetter(string str, int Index);

Is the character between A and Z or a and z?

Char.IsUpper(string str, int Index);

Is the character uppercase?

Char.IsLower(string str, int Index);

Is the character lowercase?

Char.IsLetterOrDigit(string str, int Index);

Is the character a letter or a digit?

For each of the above there is an alternative formulation. For example:

if(IsDigit(strTB[5])) [One argument].......

is the same as:

if(IsDigit(strTB, 5)) [Two arguments]

Common Conversions

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