1. From lab 1 Using cs lab machines (including remote)
Function prototype vs function definition
Submitting to mycourses
Naming convention: Ass1_lastName_Firstname.tar.gz
no unneeded files

2. Any problems using zylabs?

3. Week 2 - goals File i/o in c++
Decomposing a program using a structure/hierarchy chart
Style standards for cs240 programs
The run-time stack
String and vector classes

5. <ios> <istream> <iostream> <fstream> <sstream>
ifstream
istream
ios_base
istringstream
cin
iostream
ostream
ostringstream
ios
cout

6. File I/O <fstream> contains definitions for 2 classes
Ifstream and ofstream
Programmer creates an object and connects the object to an OS file
Ifstream myinfile (“inputDataFile”); must be an existing file
Ifstream myfile; //read the filename into a string variable named filename myfile.open(filename.c_str()); - why not just filename?
Ofstream myoutfile(“out_put_file_name”); will erase an existing file
Making sure file was successfully open
If(myfile.isopen()) ----
If(Myfile) -----
Myfile.close(); breaks the connection and frees resources being used
Myfile.eof(); returns true if end_of_file has been reached

7. Extraction (>>) vs. getline()
Both read characters from an input stream (terminal or file)
>> skips over any white space characters and then extracts all characters up to but not including the next white space character
Getline(cin, line); reads all characters up to the next newline character and disposes of the newline character

8. consider
You have to read from a text file that contains information about a list of contacts
Each line of the file contains
A name (first name only)
A cell phone number (10 digits)
(optionally) a home phone number (10 digits)
You can assume that the input file is correctly formatted

9. Use extraction (>>) or getline?
Sample file: joe idil can

10. Istringstream class
Inherits from istream so has all the methods that cin or an ifstream object has
Constructors
Istringstream instream();
Istringstream instream(str);
Some methods
Void str(const string & s); s becomes the contents of the istringstream
Bool eof(); returns true if end-of-file was reached by last input operation

11. Using the istringstream class you can:
read a line from a file or cin using getline
create an istringstream object from
the string extract “tokens” from the istringstream

12. Zybook assignment
Before 11:30 on Thursday Jan 25 complete non optional exercises from
Ch. 8 Strings
Ch. 9 arrays and vectors

13. Hierarchy chart documenting Functional decomposition of Lab 1 program
main
findAverage
displayResult
getNumber
doubleLargest

14. Adding communication main findAverage displayResult getNumber
int
int
int
double
double
findAverage
displayResult
getNumber
doubleLargest
terminal
terminal

15. a message is written to the standard error device and abort is called, terminating the program execution.
Phases of development
Specification what is the program supposed to do?
Design decompose into functions and/or classes
Implementation implement the components
testing does the program meet its specification?
Maintenance make changes after program is in use

16. A problem to solve
Write a C++ program that prompts the user for the name of a text file, opens that file, reads the file and stores the lines of the file in a vector of strings.  The program should output the number of non-blank lines in the file, the average number of words per non-blank line and the average number of alphabetic characters per word.

17. The big problem text file program number of non-blank lines
avg words per non-blank line
avg alphas per word
program

18. understanding the problem
Any questions?

19. Some questions What is a word? What is a non-blank line?
A sequence of non-white space characters containing at least one alpha character
What is a non-blank line?
Contains at least one non-white space character
What is an alpha character?
Upper or lower case A through Z

20. Create some test cases Helps to understand the problem
Use after program is written
Correct answer is known before executing the program

21. number of non-blank lines avg words per non-blank line
This is a test case
How many non-blank lines are there?
Average words/non-blank line?
Average alphas / word?
number of non-blank lines
avg words per non-blank line
avg alphas per word

22. Some other test cases?? number of non-blank lines: 4
This is a test case
How many non-blank lines are there?
Average words/non-blank line?
Average alphas / word?
number of non-blank lines: 4
avg words per non-blank line:
4.25
avg alphas per word:
4.88
Some other test cases??

23. Design involves decomposing big problem into smaller problems
Divide and conquer
What are some smaller problems?

24. Some smaller problems Open the input file Display the results
Read from the input file into a vector
Is a line blank?
Number of words in a line?
Number of alphas in a word?

25. Hierarchy chart as a design tool
Use hierarchy chart to develop functional decomposition
Each box represents a function that solves one piece of the problem
Communication with its caller shown
External I/O shown

26. main

27. OpenFile

28. Incremental development
Bottom up
Implement and test individual functions
Top down
Write main using stubs for lower level functions

29. Zybook assignment
Before 11:30 on Tuesday Jan 30 complete non optional exercises from
Ch. 10 (sec 1 to 7) classes and objects

30. assignments How to submit Grading criteria See course information page
See assignment Assignment 1

31. Cs240c style standards Decompose program into functions
Main consists of calls to other functions
Each function has a single job to do
Organize programs as shown in class
Document each function prototype
Use meaningful names for variables, parameters, functions, classes, etc.
One statement per line
Indentation must follow program logic
Use blank lines and spaces for readability
Appropriately label all output
Avoid wrap around when printed
Use break only in a switch statement
Do not use global variables
See Chapter 6.3 of zyBook

32. Who are the readers of your code?

33. some readers of your code
compiler
Grader
You
Team members (for team projects)
maintainers

34. Quiz 1 Given: string str1; string str2 = “Cs240c”;
Length(str1) returns: ____
Str2.at(3) returns: ____
Strings can be compared using relational operators (true or false)
str2.insert(3,”-”) makes the value of str2: _________
Str2.find(‘c’) returns: _____
Myvector[i] and myvector.at(i) have the same behavior (true or false) given: vector<int> nums;
nums.size() returns: ____ given: vector<char> chars (26); chars.push_back(‘.’);
chars.size() returns: ______

35. Given: string str1; string str2 = “Cs240c”;
Length(str1) returns: _0___
Str2.at(3) returns: _4___
Strings can be compared using relational operators (true)
str2.insert(3,”-”) makes the value of str2: _CS2-40c__
Str2.find(‘c’) returns: __0___
Myvector[i] and myvector.at(i) have the same behavior (false) given: vector<int> nums;
nums.size() returns: _0___ given: vector<char> chars (26); chars.push_back(‘.’);
chars.size() returns: __27____

36. Where can you find a list of all of the methods of the string or the vector class?

37. Type char What is the difference between ‘c’ and “c” ?
See <cctype> for useful functions dealing with the char
Also covered in zybook 8.3

38. vector<T>
One of several container classes provided by the c++ standard Template Library (STL)
Is a template class – pattern used to instantiate a real class (instance)
Vector<string> words;
Vector<int> numbers;
Vector<myclass> list;
Vectors contain a sequence of elements that occupy positions 0 to size-1
Elements can be added to, removed from or accessed by position

39. How is a vector different from a c or C++ array?

40. Some differences Vector is a template class
A vector knows its own size
Size can grow and shrink as needed
Has a size and a capacity
Has many useful methods
Provides element access with range checking
Can be used with many functions from the <algorithm> library
Ex: Sort, find, for_each, copy, max_element