For answers, see answers. Please attempt each question before checking the answer.

1. Write the number -342.81 using the C floating point notation, and starting with -3.4...

2. What is the binary number 101101 equal to as a decimal number?

3. What is the C hexadecimal constant 0x2d equal to at a binary number? As a decimal number?

4. In each case give the value of the C expression:

   
   3 + 4*5
   3.2 + 4
   (int)(4.7 - 3)
   3/4
   15%4
   

5. Write a segment of code that will start with three double variables a, b, and c, and will compute the double d = b² - 4 a c . Then an if-else should check and print either "real, not equal", "real, equal", or "complex", depending on the value of d.

6. Fill in the rest of the printf so that it will produce the output show:

   
   int n = 3; /* or  int n = 2; */
   double x = exp(n);
   printf( /* answer here */ );
   
   Output:
   e to the power 3: 20.085536923187
   
   Output if "int n = 3;" is changed to "int n = 2;"
   e to the power 2: 7.389056098930
   

7. Write a short code segment that will declare two doubles, will read them, will calculate the smaller of the two, and finally will print the smaller value.

8. Consider the infinite loop that was presented in class:

   #include <stdio.h>
   int main () {
      double x = 0.1;
      while (x != 1.0) {
         printf("x = %20.15f\n", x);
         x = x + 0.1;
      }
   }
   

   Explain why this is an infinite loop.

   Add code that uses a counter to stop the loop after 25 iterations. (Do this without looking up the answer.)

9. Write a loop that adds up the odd integers from 1 to 49 and prints the result.

10. Work on the examples from Practice with Loops. (Altogether there are 10 short problems here.)

11. Write a function named disc that will take three input double parameters a, b, and c, and will compute b² - 4 a c and return this value. Show a call to this function using parameter values 1.0, -4.0, and 4.0.

    Make use of this function in the earlier example involving the same type of data.

12. Write a C program segment that will read an integer n using scanf, and then will print a hollow triangle of stars of height n, as shown below for n == 10 and n == 5. (Assume that n > 1 The program needs to work for general n and not just 10 and 5, so you must use a loop in the program.)

    10 * ** * * * * * * * * * * * * * * **********

    5 * ** * * * * *****

    13 * ** * * * * * * * * * * * * * * * * * * * * *************

    3 * ** ***

    2 * **

    8 * ** * * * * * * * * * * ********

    You may use the following function to help print the characters:

    void chars(int n, char ch) {
       int i;
       for(i = 0; i < n; i++)
          printf("%c", ch);
    }
    

    Here, the format code %c is used to print a single character, so that chars(5, '*') will print 5 stars with no newline, and chars(4, ' ') will print 4 blanks with no newline.

13. Using the same methods as the previous problem, try to print a "tree" of the following form, for different initial values of n.

    8 * *** ***** ******* ********* *********** ************* ***************     *** *** ***

    6 * *** ***** ******* ********* ***********     *** *** ***

    10 * *** ***** ******* ********* *********** ************* *************** ***************** *******************     *** *** ***

    3 * *** *****     *** *** ***

    12 * *** ***** ******* ********* *********** ************* *************** ***************** ******************* ********************* *********************** *** *** ***

14. Suppose rand_double() returns a uniformly distributed random double between 0 and 1. Use this function to similate rolling three dice at a time. Keep rolling until you roll three 1's, counting as you go. Print how many rolls it took until you rolled the three 1's.

15. Redo the program so that it will keep rolling 3 dice until all three dice come up with the same number (not necessarily just 1). The print how many rolls it took to roll the same number on all three dice.