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Language basics and first controls

Language basics and first controls. Learning Outcomes Part I. We will learn about : Data types Naming convention Assignments and comments Converting data types Math functions Operators and comparisons. Naming convention. C# is case sensitive Naming convention

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Language basics and first controls

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  1. Language basics and first controls

  2. Learning OutcomesPart I We will learn about : • Data types • Naming convention • Assignments and comments • Converting data types • Math functions • Operators and comparisons

  3. Naming convention • C# is case sensitive Naming convention • Variables start with lowercase letter. • Methods and Classes start with Capital letter • Separate words with Uppercase letter : upperCase’ would be a variable. • Controls should start with three letters indicating the control: lblTitle, btnStop, txtName

  4. Data types Basic data types: Integer : byte, int, long Floating point: float, double Characters: char, string Logical: bool Declaration: Datatype name ( = initValue);

  5. Declarations Examples: const double PI =3.14159; const int MAXSIZE = 10, MINSIZE = 1; int Number; double Numberf = 34.5; char c1, c2; bool test = true; string Message = “Cancel”;

  6. Assignment and Comments Assignments: ‘=‘ var= expression; sum = one + two; Comments: /* Slash-star is a multi-line comment- end with a star-slash */ // a double slash which ignores the rest of the line

  7. Operators Operators: Usual operators and order of operation (precedence): +, -, *, /, % ==, !=, >, <, <=, >= Relational Logic operators: AND a = a & b; OR a= a | b; NOT a= !b; XOR a= a ^ b;

  8. Shortcuts Shortcuts X = X + 3; X+=3; div = div / 4; div /= 4; mult = mult * 5; mult *= 5; sub = sub - 2; sub -= 2; rem = rem%4; rem %= 4; Increment i++; ++i : decrement --i ; i--;

  9. Math functions Some Math functions: Sin, Cos, Tan, Exp Log - Returns the logarithm of a specified number. Log10 - Returns the base 10 logarithm. Pow - Returns a number raised to a specified power. Round - Rounds to the nearest integer or decimal places. Sqrt - Returns the square root of a specified number. Truncate - Calculates the integral part of a number. ‘

  10. Comparison == equal to != not equal to < less than <= less than or equal to > greater than >= greater than or equal to && AND || OR

  11. Summary Covered: • Variables constants and data types • Naming convention • Assignments and comments • Operators • Math functions • Logic Operations • Comparison

  12. Learning Outcomes Part II • You will learn about : • GUI • Controls • Button, TextBox, ListBox • Properties and Events • Dialog boxes

  13. GUI and Controls • GUI - Graphical User Interface • How your user interfaces with your program • You can make it really easy (or difficult) for the user! • Lots of controls • e.g. buttons, textboxes, labels, menus • You place them on the form • IDE groups similar controls together • You write code for them

  14. Common controls • Common Controls – in Toolbox • Button • TextBox • ListBox • Label • Checkbox • Radio buttons • Picture box • Menu • ..... • All have properties and events

  15. Button control • Main properties: • Appearance – Color, Image, Text • Behavior – Enabled, Visible • Design – Name • Layout – Location, Size • ........ • Main events: • Click • Double-click

  16. Text Box Control • Properties – Similar to button, but also text entry • Text (single line) • Lines (multiline) • MultiLine is a property • ReadOnly • Events • Keyboard events • TextChanged • Focus – Enter

  17. Text Box control • Reading text • Text property – all text • Individual lines: • textBox1.Lines[0]; • Add text using AppendText • textBox1.AppendText("new text"); • To add on new line: • textBox1.AppendText("\r\nnew last line"); • Backslash indicates non-printing characters • Number of Lines? • textBox1.Lines.Length

  18. TextBox Control • Conversion • String to int • int N; • N = Convert.ToInt(textBox1.Text); • or • N = int.Parse(textBox1.Text); • int to string: • int i = 20; • textBox1.AppendText(i.ToString())

  19. ListBox Control List of selectable items Properties: Items (collection) ScrollBars (Horizontal & Vertical) MultiColumn Events Click SelectedIndexChanged

  20. TextBox and ListBox TextBox and ListBox text properties Text – all the text in the text or list box. Lines[0] – first line of text or list box – read only AppendText(“new text”); – adds text to textbox Lines.Length – number of lines in textbox ListBox Items.Add(“new list item”); Items.Insert(lineNo, “inserted text”); Clear(); SelectedItem Data is a string – need to convert for numbers.

  21. Dialog Boxes Easy way to display text information. A dialog box is not a control it is displayed when program runs MessageBox.Show(Message);

  22. Dialog Boxes You Can add Caption, buttons and icon: MessageBox.Show("This will format your disk!", "Format caption", MessageBoxButtons.OKCancel, MessageBoxIcon.Exclamation); Check response with DialogResult.OK DialogResult.Cancel DialogResult.Yes …..

  23. Summary Covered • GUI • Controls • Button, Textbox etc • Properties and Events • Dialog boxes

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