Input and Output
Question 1) Which one of the following is an abstraction for providing input to a program while it is running?
Command-line arguments
Standard output
Standard input
System type conversion
Compiler arguments
Question 2) Which of the following tasks could be implemented as a filter using only a constant amount of memory (e.g., a couple of int or double variables and no arrays)? Mark all that apply.
For each, the input comes from standard input and consists of n real numbers between 0.0 and 1.0.
Print the average of the n numbers
Print the n numbers in increasing order
Print the sum of the squares of the n numbers
Print the median of the n numbers n
Print the n numbers in uniformly random order
Print the maximum and minimum values of the n numbers
Print the percentage of numbers greater than the average of the n numbers
Question 3) Which of the following are advantages of using standard input (Stdln) instead of command-line arguments? Mark all that apply.
There is no need to format the data
The StdIn library is built in to Java
We can input strings, not just numbers
Conversion to primitive types is explicitly handled
There is no artificial limit on the amount of data we can input to a program
We can provide new values while the program is executing
Question 4) Which of the following mechanisms enable us to write programs having no artificial limit on the amount of data they can handle? Mark all that apply.
Command-line arguments
Piping
Standard drawing (StdDraw)
Standard output (Stdout)
Arrays
Question 5) Consider the following program
public class Q45
{
public static void main(String [ ] args)
{
while (!StdIn.is Empty ())
{
int x = StdIn.read Int () ;
if (!StdIn . isEmpty ()) x +- StdIn.read Int () ;
}
StdOut.print (x + " ");
}
StdOut.println ();
}
Suppose that the standard input stream consists of a sequence of eight 15, separated by whitespace. Give the value printed when this command is issued:
java Q45 <input.txt | java Q45 | java Q45
Answer: 8
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