To help solidify your understanding of this hour's lesson, you are encouraged to answer the quiz questions and finish the exercises provided in the Workshop before you move to the next lesson. The answers and hints to the questions and exercises are given in Appendix E, "Answers to Quiz Questions and Exercises."
Quiz
Are the following two statements equivalent?
rewind(fptr);
(void)fseek(fptr, 0L, SEEK_SET);
Are the following two statements equivalent?
rewind(fptr);
(void)fseek(fptr, 0L, SEEK_CUR);
After the statement
freopen("test.txt", "r", stdin);
scanf("%s%d", str, &num);
Given that the size of the double data type is 8 bytes long and includes four double data items, if you write the four double data items into a binary file, how many bytes do the four data items take in the file?
Exercises
Assume that the following paragraph of Tao Te Ching is saved in a text file called LaoTzu.txt:
Be bent, and you will remain straight.
Be vacant, and you will remain full.
Be worn, and you will remain new.
Write a program to use ftell() to find the positions of the three strings in the file, and then call fseek() to set the file position indicator in such a way that the three strings are printed out in reverse order.
Rewrite the program you made in exercise 1 by calling the rewind() function to reset the file position indicator at the beginning of the LaoTzu.txt file.
Given a double value of 123.45 and an int value of 10000, write a program to save them into a binary file, called data.bin, and then read them back from the binary file. Also, print out what you're writing or reading. What do you think the size of the binary file will be?
Read the text file strnum.mix, which is created by the program in Listing 22.3. Redirect the input stream so that you can use the scanf() function to perform the reading operation. (Note that if you're using Microsoft Visual C++ on your machine, make sure the project type is set to MS-DOS application (.EXE).)
