1. Using the Console

2. Topics The Console Console Input Parsing String Data Console Output
Format Specifiers
A Little Math

3. At the completion of this topic, students should be able to:
Objectives
At the completion of this topic, students should be able to:
Tell what the console is
Describe how to read data from the console
Parse String data into integers and doubles
Describe how to write data to the console
Explain how to use format specifiers
Write C# programs that correctly
read from the console
write to the console
format data for output

4. When a Console program executes, the C# runtime
environment automatically creates these two stream
objects to help manage Console input and output.
display buffer
output buffer
Console.Out
program
keyboard buffer
keyboard buffer
program
Console.In

5. Console.ReadLine( )
The Console class provides the ReadLine( ) method to read
data from the standard input stream, Console.In. This method
waits for the user to type in some data and press the Enter key.
The ReadLine( ) method returns the data that the user typed in
as a string object.
keyboard buffer
keyboard buffer
Console.In
program

6. String name; name = ReadLine( ); John Doe keyboard buffer John Doe
Console.In
name
When using the Console class, be sure to add
using static System.Console;

7. When dealing with numbers, we have to use the
Parse method to convert the string value into
the appropriate numerical data type
int age = 0;
age = int.Parse(ReadLine( ) ); 25
keyboard buffer
Parse
method
keyboard buffer 25
the string “25”
age
Console.In

8. When dealing with numbers, we have to use the
Parse method to convert the string value into
the appropriate numerical data type
double money = 0.0;
money = double.Parse(ReadLine( ) );
12.50
keyboard buffer
Parse
method
keyboard buffer
12.50
The string “12.50”
money
Console.In

9. Console.WriteLine
The Console class provides the WriteLine( ) method to write
To the standard output stream, Console.Out. This method
takes a string as it’s parameter. After writing to the display,
the cursor is moved to the next line.
display buffer
output buffer
Console.Out
program

10. Console.WriteLine string name = “Joe Coder”; WriteLine( name );
display buffer
Joe Coder
output buffer
Console.Out
Joe Coder
name

11. Console.WriteLine Numbers are automatically converted to
strings by the WriteLine( ) method:
double money = 12.50
WriteLine( money);
display buffer
12.50
output buffer
Console.Out
12.50
money

12. Console.WriteLine You can combine string literals and numerical data
using the placeholder { .. } to mark the place where
the numerical data should be displayed.
double money = 12.50
WriteLine($ “You owe {money} to me.”);
display buffer
You owe to me
output buffer
Console.Out
12.50
money

13. Console.WriteLine You can use a format string to format the output
double money = 12.50
WriteLine($ “You owe {money:C} to me.”);
display buffer
You owe $12.50 to me
output buffer
Console.Out
12.50
money

14. Formatting Specifiers
D or d: Display an integer value as a decimal number
F or f: Display a real value - default is two digits after the decimal point
C or c: Display a real value as currency

15. With an integer you can use a number to
Formatting Strings
With an integer you can use a number to
indicate how many digits to display
int number = 23;
WriteLine($“The value is {number:D4}” );
The value is 0023

16. With a double you can use a number to indicate
Formatting Strings
With a double you can use a number to indicate
how many decimal digits to display
double number = ;
WriteLine($“The value is {number:F3}“);
The value is

17. You can arrange things on the screen by using numbers
Formatting Strings
You can arrange things on the screen by using numbers
to specify a field width and justify the output in the field.
double number = ;
Console.WriteLine($“The value is {number, 6:F2}” ); 2 3 . 9 8
The value is _23.98
6 character field

18. Data displayed on a Graphical User Interface
must first be converted to a string.
That string is then assigned to the Text Property
of the control where you want to see it.

19. Suppose the name of this TextBox control is “outputTxtBox”
and we have an integer named sum to show there.
outputTxtBox.Text = $”{sum:f2}”;

20. Practice
Name one class that we have learned about in this
lesson.

21. Practice Which method is used to convert data into its
character representation and send it to the
standard output device?
To what class does this method belong?

22. Practice Name a method that is used to convert numerical data
from its character representation and store it to in
memory in its binary representation.

23. Practice Write a program that prints the message
“Hello, my name is Hal”.
Then the program will prompt the user for his
or her first name. It then Will print
“Hello, user name, how are you?”

24. Practice Write a program that prints the message
“Hello, my name is Hal”.
Then the program will ask the user for his or her name.
Get the name and save it in a String object.
Then print the message
“Hello, user name, how are you?”
Prompt the user to type in their age. Save it in an
Integer. Then print the message
“user name, you are n years old”

25. Practice Write a program that does the following:
Declares an integer, a double, and a character.
In turn, asks the user to enter in an appropriate piece of data
for each variable and stores it in that variable.
Add together the integer and the double and the
character. The result is stored in a double named sum.
Print out the sum.
Ask the user to type their name (first and last).
Store their name in a string variable.
Print out “Thank you (their name).
Be able to discuss the results of your program.