Книга: Advanced PIC Microcontroller Projects in C

3.5 Exercises

3.5 Exercises

1. Write a C program to set bits 0 and 7 of PORTC to logic 1.

2. Write a C program to count down continuously and send the count to PORTB.

3. Write a C program to multiply each element of a ten element array by 2.

4. Write a C program to add two matrices P and Q. Assume that the dimension of each matrix is 3?3 and store the result in another matrix called W.

5. Repeat Exercise 4 but this time multiply matrices P and Q and store the product in matrix R.

6. What do the terms variable and constant mean?

7. What does program repetition mean? Describe the operation of while, do-while, and for loops in C.

8. What is an array? Write example statements to define the following arrays:

 a) An array of ten integers

 b) An array of thirty floats

 c) A two-dimensional array having six rows and ten columns

9. Trace the operation of the following loops. What will be the value of variable z at the end of each loop?

 a)

unsigned char j = 0, z = 0;
while (j < 10) {
 z++;
 j++;
}

 b)

 unsigned char z = 10;
 for (j = 0; j < 10; j++) z--;

10. Given the following variable definitions, list the outcome of the following conditional tests in terms of “true” or “false”:

unsigned int a = 10, b = 2;
if (a > 10)
if (b >= 2)
if(a == 10)
if (a > 0)

11. Write a program to calculate whether a number is odd or even.

12. Determine the value of the following bitwise operations using AND, OR, and EXOR operations:

Operand 1: 00010001
Operand 2: 11110001

13. How many times does each of the following loops iterate, and what is the final value of the variable j in each case?

 a) for(j = 0; j < 5; j++)

 b) for(j = 1; j < 10; j++)

 c) for(j = 0; j <= 10; j++)

 d) for(j = 0; j <= 10; j += 2)

 e) for(j = 10; j > 0; j -= 2)

14. Write a program to calculate the sum of all positive integer numbers from 1 to 100.

15. Write a program to evaluate factorial n, where 0! and 1! evaluate to 1 and n! = n ? (n – 1)!

16. Write a program to calculate the average value of the numbers stored in an array. Assume that the array is called M and has twenty elements.

17. Modify the program in Exercise 16 to find the smallest and largest values of the array. Store the smallest value in a variable called Sml and the largest value in a variable called Lrg.

18. Derive equivalent if-else statements for the following tests:

 a) (a > b) ? 0 : 1

 b) (x < y) ? (a > b) : (c > d)

19. Given that f1 and f2 are both floating point variables, explain why the following test expression controlling the while loop may not be safe:

do {
 ...............
 ...............
} while(f1 != f2);

Why would the problem not occur if both f1 and f2 were integers? How would you correct this while loop?

20. What can you say about the following while loop?

k = 0;
Total = 0;
while (k < 10) {
 Sum++;
 Total += Sum;
}

21. What can you say about the following for loop?

Cnt = 0;
for (;;) {
 Cnt++;
}

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