Description
This short assignment is designed to deepen your understanding of C++ I/O and of character representations. 1 Assignment Goals 1. Learn how to use command line arguments. 2. Learn how to open a file and read its contents. 3. Learn how characters are represented by bytes in the computer. 4. Learn the difference between a character and its ASCII code. 5. Learn how to obtain the ASCII code of a character stored in a variable of type char. 6. Learn how to print the character whose ASCII code is stored in a variable of type int. 7. Learn how to print an int as a decimal number. 8. Learn how to print an int as a hex number. 9. Learn how to test if a char is printable. 10. Learn how to use the output manipulators dec, hex, setw(), and setfill() to control the printed form of numbers. 11. Learn precisely what in>>val does to the istream in when val has type int. 12. Learn how to use in.get(ch) to read a single character from in. 13. Learn precisely what out<>x. If a number is successfully read into x, then x should be printed in decimal on a line by itself. If the attempt to read x fails, then the next character should be read from the stream using in.get(ch), where ch has type char, and a one-line “Skipping. . . ” message should be printed. Depending on the character read, the message might look like either of the following: Skipping char: 116 0x74 ’t’ Skipping char: 0 0x00 2 Problem Set 2 In each case, the ASCII code of ch is printed first in decimal, right-justified in a 3-character field without zero-fill, and then again in hex, prefixed by “0x”, followed by a right-justified 0-filled hex number in a 2-character field. If ch is printable as defined by isprint()1 , then it should also be printed as a character, enclosed in single quotes as shown. For example, if file data.in contains the text: Score was 35to21. the output should be: ————————————————————— Ima Goetting Closeau CPSC 427/527 Tue Oct 4 2016 11:18:06 ————————————————————— Skipping char: 83 0x53 ’S’ Skipping char: 99 0x63 ’c’ Skipping char: 111 0x6f ’o’ Skipping char: 114 0x72 ’r’ Skipping char: 101 0x65 ’e’ Skipping char: 119 0x77 ’w’ Skipping char: 97 0x61 ’a’ Skipping char: 115 0x73 ’s’ 35 Skipping char: 116 0x74 ’t’ Skipping char: 111 0x6f ’o’ 21 Skipping char: 46 0x2e ’.’ Loop exit ————————————————————— Normal termination. Be sure you understand why there is no “Skipping” line for the spaces following “Score” and “was”. What happened to those characters? 3 Programming Notes This program is very short and may be put entirely in the run() function in main.cpp. You must read x using the stream extract operator >>. You may not use stringstream or getline() or other methods to read the line as a string or to read individual digits that comprise a decimal number. You must let the stream do your decimal to binary conversion. Do not call atoi() or strtol() or any other means of manually converting a string to an int. To obtain the ASCII code of a character stored in a char variable ch, cast ch to an int. Similarly, to print a character whose ASCII code is stored in an int variable x, cast x to a char before printing. 1 See http://www.cplusplus.com/reference/cctype/isprint/. Handout #4—September 16, 2018 3 Grading Rubric Your assignment will be graded according to the scale given in Figure 1 (see below). # Pts. Item 1. 1 All relevant standards from PS1 are followed regarding submission, identification of authorship on all files, and so forth. 2. 1 A well-formed Makefile or makefile is submitted that specifies compiler options -O1 -g -Wall -std=c++17. 3. 1 Running make successfully compiles and links the project and results in an executable file readint. 4. 1 Your program gives a usage comment and terminates if the wrong number of command line arguments are given. It gives a descriptive error comment if the specified input file does not open. 5. 4 All instructions given in sections 2 and 3 are carefully followed. 6. 4 Your program correctly extracts all of the integers in the file. 7. 4 Your program prints a correct “Skipping. . . ” message following each failed attempt to read an integer. 8. 2 The “Skipping. . . ” message exactly follows the examples and instructions, including spacing and when to print leading 0’s and when not to. 9. 2 Your program correctly handles end-of-file, regardless of whether the EOF is immediately preceded by whitespace, a digit, or another character. 20 Total points. Figure 1: Grading rubric.
