VISUAL C# EXERCISES▼
- Creating forms (4)
- Coding form events (1)
- Laying out your code (2)
- C# variables (4)
- Enumerations and constants (2)
- Conditions (2)
- Modular code (3)
- Arrays (2)
- Looping (2)
- Files and folders (3)
- Properties in C# (3)
- Using lists (3)
- Validating forms (6)
- Toolbars, menus and status bars (1)
- FileDialogs and StreamReaders (1)
- Debugging and trapping errors (1)
- Introduction to DataGridViews (1)
- DataGridView events (3)
- Complex DataGridViews (2)
- Creating classes (4)
- The form as a class (1)
- Data structures (6)
- Inheritance (5)
- Interfaces (2)
- Delegates and events (2)
- Writing LINQ (2)
- Advanced LINQ (2)
- Entity Frameworks (1)
- LINQ with Entity Frameworks (4)
- Grouping using LINQ (2)
- LINQ to SQL (2)
Visual C# | Validating forms exercise | Validating name and age entered
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Add the existing form shown above to your project - you should see this:
Initially there is no validation applied
Add code to the Validating event of the txtName textbox, so that if the user leaves the length of this textbox as zero you see an error message:
This is what you should see if you leave the name blank
Now do the same for the txtAge field, but this time check that it is a whole number:
The age must be filled in, and must be a whole number
The easiest way to do this is with a try ... catch ... clause, within which you attempt to convert the age filled in into an integer.
Finally, add code to the Age field's Validated event so that the age is increased by 10 years after it has been checked:
Acknowledge the fact that no one tells the truth about their age ...
You should now see that the Validated event fires whether you change the value in their Age text box or not. How might you stop your age increasing by 10 years every time a user leaves the Age text box?