Ppt lesson 07


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Ppt lesson 07

  1. 1. Microsoft Visual Basic 2005 BASICS Lesson 7 Strings and Decimal Types
  2. 2. Objectives <ul><li>Declare string variables. </li></ul><ul><li>Assign text to string variables. </li></ul><ul><li>Concatenate strings. </li></ul><ul><li>Use decimal data types. </li></ul><ul><li>Use the Format function. </li></ul>
  3. 3. Objectives (cont.) <ul><li>Use the Enabled property. </li></ul><ul><li>Use the SelectionStart and SelectionLength properties. </li></ul>
  4. 4. Declaring String Variables <ul><li>Text is often called alphanumeric data. </li></ul><ul><ul><li>Can include letters or numbers </li></ul></ul><ul><li>Data types that hold text are usually referred to as strings. </li></ul><ul><li>When you declare a string, t he resulting variable can hold a string of any practical length. </li></ul>
  5. 5. Assigning Text to String Variables <ul><li>Place the text in quotation marks. </li></ul><ul><li>Hard-coded text is called a string literal. </li></ul><ul><li>Like a numeric variable, a string variable can only hold one string. </li></ul><ul><li>Each time you assign a string to a string variable, the existing data is replaced. </li></ul>
  6. 6. Assigning Text to String Variables (cont.)
  7. 7. Assigning Text to String Variables (cont.)
  8. 8. Concatenation <ul><li>Concatenation </li></ul><ul><ul><li>Appends one string to the end of another </li></ul></ul><ul><li>Ampersand (&) </li></ul><ul><li>You can concatenate more than two strings in one expression. </li></ul><ul><li>You can also use concatenation when creating the text for a label. </li></ul>
  9. 9. Concatenation (cont.)
  10. 10. Concatenation (cont.)
  11. 11. Concatenation (cont.)
  12. 12. Concatenation (cont.)
  13. 13. Using Decimal Types <ul><li>Single data type </li></ul><ul><ul><li>Used for decimal values that will not exceed 38 digits </li></ul></ul><ul><li>Double data type </li></ul><ul><ul><li>Used for decimal values with more than 38 digits </li></ul></ul><ul><li>Decimal data type </li></ul><ul><ul><li>Used to work with dollars and cents </li></ul></ul>
  14. 14. Using the Format Function <ul><li>The Format function </li></ul><ul><ul><li>Allows you to apply custom formatting to a number before displaying the value </li></ul></ul><ul><li>The Format function can be used to format decimal values, phone numbers, and more. </li></ul>
  15. 15. Using the Format Function (cont.)
  16. 16. Using the Format Function (cont.)
  17. 17. Using the Format Function (cont.)
  18. 18. Using the Enabled Property <ul><li>Enabled property </li></ul><ul><ul><li>Makes a control take on a grayed appearance that makes it inactive but still visible </li></ul></ul><ul><li>Objects that are inactive can be seen by the user, but will not respond to user actions. </li></ul>
  19. 19. Using the Enabled Property (cont.) <ul><li>To disable an object, set the Enabled property to False. </li></ul>
  20. 20. Using the SelectionStart and SelectionLength Properties <ul><li>SelectionStart property </li></ul><ul><ul><li>Specifies the location where the insertion point will be inserted when the text box gets the focus </li></ul></ul><ul><li>SelectionLength property </li></ul><ul><ul><li>Specifies how many characters should be selected to the right of the cursor </li></ul></ul>
  21. 21. Using the SelectionStart and SelectionLength Properties (cont.)
  22. 22. Summary <ul><li>Strings hold text or alphanumeric data. </li></ul><ul><li>Visual Basic has a data type for strings. </li></ul><ul><li>Text assigned to a string variable must be placed in quotation marks. </li></ul><ul><li>You can use the assignment operator to assign text from a text box to a string variable or from a string variable to another string variable. </li></ul>
  23. 23. Summary (cont.) <ul><li>Concatenation is the process of appending one string to the end of another. </li></ul><ul><li>The ampersand (&) is the symbol used for concatenation. </li></ul><ul><li>The Single, Double, and Decimal data types hold decimal data. </li></ul><ul><li>The Decimal data type is specially designed for handling dollars and cents. </li></ul>
  24. 24. Summary (cont.) <ul><li>The Format function uses a string of symbols to format decimal values, phone numbers, and more. </li></ul><ul><li>The Enabled property is used to make a control inactive or active. </li></ul><ul><li>The SelectionStart and SelectionLength properties and the Len function can be used together to highlight the text in a text box. </li></ul>