This is a list of topics intended as a checklist to help you recall what topics have been covered since Test 1, both in lecture class and in the textbook.

Other Function Topics (continued)

Pass by Reference

• Reference variables
  • use & notation when declaring
  • an alias for another variable (i.e. nickname)
  • useful when variables are in different scopes (i.e. functions)
  • used in parameter passing and return values
• Pass by Value - local copies of parameters are made, and copies of returns are sent back
• Pass by Reference - Copies of parameters and returns are not made. Local parameters are references to the originals
• Use of const with reference parameters to prevent a function from changing the original (but avoid overhead of making a copy - faster execution)

Input / Output Libraries

File I/O

• Understand types of files
  • Formatted text vs. binary
  • sequential vs. random access
• Understand the objects cin and cout, and what classes they are built from
• library <fstream>
  • class ofstream -- for output file streams
  • class ifstream -- for input file streams
  • Know how to declare file stream objects
• Know how to attach files to stream objects
  • member function open()
  • Default modes of opening for input files and output files
  • Understand the variation -- append mode
  • Know how to check to see if the file successfully opened
  • member function close() to close a file
  • stream can be reused for another file
• Using file streams -- similar syntax as with cout and cin
• Know the basic syntax for getting a user-entered filename (using an array of characters)

Other I/O Stream Features

• eof() function
• put() -- for character output
• The two get() functions, for extracting character input
  • Understand how each of these are called
  • Understand how they differ from reading a char with the extraction operator >>.
• peek()
• ignore()
• putback()
• Know how to pass stream objects into functions (by reference)
  • Understand how to build functions that allow this
  • Understand how to call functions that do this
  • Understand the relationship between istream and ifstream, for instance, and which objects can be passed with which formal parameters. (same for ostream / ofstream)

Misc -- cctype library

• A useful C library of character handling functions
• toupper(), tolower()
• Understand the boolean functions whose names start with is, for determining if a character fits in a certain given category

Arrays

Array Properties

• indexed collection of data elements of same type
• consecutive storage locations
• default indexing is 0 through size-1 (where size is the number of elements in the array)

Declaring Arrays

• format:   typeName variableName[size];
• Example:  int list[10]
• The type can be any basic type or any user-defined type
• the size must be known by the compiler, so it must be a positive integer literal or constant.
• 2-dimensional arrays
  • Example:  double table[5][10]

Initializing Arrays

• Can initialize arrays in the same line as declaration
• Format:    type name[size] = { list of elements };
  • Example:  int list[5] = {1, 3, 5, 9, 10};
• The list of elements goes in { } and is separated by commas
• may leave size box empty when initializing on the declaration line - compiler sets size.
• Can also initialize with for loops (good with regular patterns)
• Special case
  • strings: null-terminated character arrays
  • can initialize on the declaration with a string literal
    • Example:  char name[7] = "Marvin";
  • size must leave room for null-character '\0'

Using Arrays

• valid indices are 0 through size-1.
• may use any of these index numbers to access a single array element:
• may use any positive integer r-value to index arrays (i.e. variables, expressions, etc)
• it is the programmer's job to check for out-of-bounds index!
• Copying Arrays
  • Assignment between array names does not copy one array to another
  • If you want to copy one array to another, do it element by element (easy with a loop)

Using strings

• A string can be used like a normal array (of characters)
• cout and cin objects also work with strings (for output and input of words)
• >> operator for input stops at white space (space, tab, newline, etc.)
  • only good for one word at a time
• get and getline for reading strings from input
  • get, getline read up to specified delimiter -- can read entire sentences

Arrays as function parameters

• Know how to pass an array into a function
• Usually a good idea to pass in a size as well
• Function always has access to the array contents -- only the address is sent in
  • There's no pass-by-value vs. pass-by-reference with arrays
• Use const on the array parameter when the function shouldn't change the array
• When 2-D array passed into a function, prototype must include size of second dimension:

     void PrintMatrix(int arr[][10], int numRows);
     // This function can take any matrix with 10 "columns", assuming
     //  row/column order.
  

Array Usage and Algorithms

• Understand how to handle arrays that are declared to a certain size, but are not always "full" to their capacity
• Understand common array algorithms and patterns, including (but not limited to):
  • iterating through an array elements with a loop
  • Printing array contents
  • adding or counting array elements
  • finding largest/smallest element of an array
  • initializing array contents, with either formulas, user entry, or reading from a file
  • Using parallel arrays
  • Swapping or moving around array elements
• Arrays of strings
  • Implemented as a 2-D array of type char
  • The first dimension indicates how many strings
  • The second dimension indicates the allocated size for each string
  • Can refer to the name of one "string" by using the first index only

Arrays: Searching and Sorting

Searching

• Linear Search
  • The most obvious and intuitive search mechanism
  • Looks through array elements one by one until the item is located
  • takes longer than some specialized search techniques
• Binary Search
  • Depends on array being maintained in some sorted order
  • Looks at "middle" element, and decide which "side" of the array the element being searched for would have to be in
  • On each comparison, cuts number of possibilities in half
  • Runs much faster than linear search

Sorting

• Bubble Sort
  • Compares side-by-side elements. If out of order, swap them
  • Uses nested loops
  • Each run through inner loop "bubbles" one element to the end, its final position
  • Outer loop must run size-1 times
• Selection Sort
  • Also uses nested loops
  • Run through inner loop "selects" the largest (or smallest) element of the remaining items (i.e. the ones that are not yet in position), and swaps it with the end element
  • Outer loop must run size-1 times

<cstring> library functions:

string objects

• Built with the string class library
• variable length, flexible
• Supports more intuitive operator notations, like assignment, comparisons, + for concatenation, etc
• Understand the difference between c-strings and string objects
• Know the commonly used operators, as well as the usage of basic member functions discussed in class