## CSci 2101 Data Structures: Lab 1

Before you start, please read A very brief introduction to Linux. Please ignore the description of scp.

Tasks marked with * are extra credit. Work on these tasks only if you are not pressed for time.

### Problem 1

For this problem please create a new file LabOneProbOne.java and copy/paste the program below into it:
``````
import java.io.*;

public class LabOneProbOne {
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
// The code below reads one integer n
// prompt the user:
System.out.print("Please enter an integer: ");
// read a line of input:
String line = in.readLine();
// extract the integer from the entered data:
int n = Integer.parseInt(line);

// fill in your code here:
// print out the value of n

// increment n by 1

// print out the new value of n

System.out.println("Done!");
}
}

// What happens if the input is not an integer?
``````

• Task 1: Compile and run the program. When it asks for an integer, enter any integer number (a negative one is OK) and press Enter. The program should print `Done!`
• Task 2: What happens if you enter something other than an integer? Try it and write the answer in comments after the program.
• Task 3: Fill in the code according to the comments in the file.
• *Task 4*: Can you print the new and the old value of n on one line without changing the order of the statements in the program? The string `Done!` should still be on a separate line.
Submit the file to your Wiki lab page.

### Problem 2

Each of the following two programs have several compiler errors. Copy/paste the programs into the appropriate java files and get them to compile and run.
``````
public class LabOneProbTwo {
public static void main(String[] args) {
Int x = 5.0
double y = 2.4;

y = x + 3.3;
System.println("x = " + x + " y = " + );
}
}
``````

``````
public clas LabOneProbThree {

public void main(String[] args) {
int myVariable = 55;
myOtherVariable = myVarible + 55;
double dVariable = myVariable * 2.3 - myOtherVariable / 3.;
System.out.print("Here is the result: );
System.out.println(dVariable;
}

``````

Submit both files to your Wiki lab page.

### Problem 3

Which of the following are legal variable names in Java? Test each of the names in a program. Write your answers on your Wiki lab page (under the header Lab 1 Problem 3). Submit the program that you used to test these names together with the other files for this lab.
• r2d2
• noWay!
• 2BeOrNot2Be
• I love Java
• I-love-Java
• I_love_Java
• string
• switch
• _five_
• _5_
• anExtremelyAndAnnoyinglyLengthyVariableNameWhichIsTerriblyHardToRead

This is a lab from CSci 2101 course.

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