In this section, we will cover the fundamental concepts of input and output in MUMPS. Understanding how to handle input and output is crucial for interacting with users and managing data flow within your programs.

1. Input: Reading data from the user or another source.
2. Output: Displaying data to the user or another destination.

MUMPS provides a straightforward way to read input from the user using the READ command.

• READ "Enter your name: ", name: Prompts the user to enter their name and stores the input in the variable name.
• WRITE "Hello, ", name, "!": Outputs a greeting message that includes the user's name.

Task: Write a MUMPS program that asks the user for their age and then displays a message indicating whether they are a minor or an adult.

Solution:

• Forgetting to declare variables: Ensure that variables are properly declared and initialized.
• Incorrect syntax: Pay attention to the syntax of the READ and WRITE commands.

MUMPS uses the WRITE command to display output to the user.

• SET message="Welcome to MUMPS programming!": Assigns a string to the variable message.
• WRITE message: Outputs the content of the variable message.

Task: Write a MUMPS program that displays the current date and time.

Solution:

• Incorrect use of special variables: Ensure you understand how to use special variables like $HOROLOG for date and time.
• Formatting issues: Pay attention to how you format the output for readability.

Often, you will need to combine input and output operations in your programs.

• READ "Enter a number: ", num: Prompts the user to enter a number.
• SET square=num*num: Calculates the square of the entered number.
• WRITE "The square of ", num, " is ", square, ".": Outputs the result.

Task: Write a MUMPS program that asks the user for two numbers and then displays their sum, difference, product, and quotient.

Solution:

• Division by zero: Ensure you handle cases where the second number might be zero to avoid runtime errors.
• Incorrect arithmetic operations: Double-check your arithmetic operations for accuracy.

In this section, we covered the basics of input and output in MUMPS:

• Using the READ command to get input from the user.
• Using the WRITE command to display output to the user.
• Combining input and output operations to create interactive programs.

Understanding these fundamental concepts will allow you to build more complex and interactive MUMPS programs. In the next section, we will delve into control structures, which will enable you to make decisions and control the flow of your programs.