Lab #3: Using a map<string,float> object for maintaining the information of names and values of variables.

#1. Read the following to understand the basics of maps in C++:

i. A map as an associative container in C++: A map is internally implemented as a search tree for storing key-and-value pairs. It maps a given key to its associated value. You can access a map either (i) through the use of iterators and calls to the appropriate methods or (ii) use it as an associative array using syntax similar to what you do with ordinary arrays.

ii. Viewing a map as an associative array: A very convenient way to use a map is to view it as an associative array. For an ordinary array X, given a valid non-negative integer key index i, the ordinary array X maps it to the value X[i]. (Note that if i is not a valid index, accessing X[i] can crash your program.) For a map<string,float> object Y as an associative array, given a valid key string s, the map<string,float> object Y maps it to the float value Y[i]. (Note that if s is not a key to any values currently stored in the map, accessing Y[s] will create a new key-and-value pair that map s to something Y[s] accordingly.) Download and examine the code in mapAsAssociativeArray.cpp and compile it to see how you can use a map as an associative array to (i) insert new key-and-value pairs, (ii) examine and print out all of the current key-and-value pairs, (iii) modify the value of a key-and-value pair, and (iv) erase a key-and-value pair with a specific key.

iii. Viewing a map as a collection of key-and-value pairs: A map is internally a search tree storing key-and-value pairs, which can be accessed through the use of iterators and calls to the appropriate methods. Download and examine the code in map.cpp and compile it to see how you can (i) insert new key-and-value pairs, (ii) examine and print out all of the current key-and-value pairs, (iii) search for a key-and-value pair with a five key, (iv) erase a key-and-value pair, and (v) modify the values of the pairs using a loop. Note that when printing out the contents in the map it is in order of the keys even if the pairs were inserted into the map in any random order. This is because the map is internally a search tree that automatically provides a way to sort out things in order of the keys when we traverse the search tree through the iterator. Also read Section 10.1 in C++ Primer, which tells you about the pair type used to store key-value pairs in a map.

iv. Further references: Sections 11.1~11.3 in the 5^th ed. of C++ Primer.

#2. Create a C++ project and do the following in the main function:

Declare a map<string,float> object variableTable first. Use a loop to repeatedly (a) display a menu about the services depicted in the following, (b) ask the user to select one of the services by entering a corresponding character, and (c) provide the selected service accordingly :

· i (insert): ask the user to provide the name and the value of a variable and the program should store the information into variableTable.

· e (erase): user provides the name of a variable and the program should delete the variable (and the information of its value) from variableTable.

· v (value): user provides the name of a variable and the program should display the value of the variable if a variable of that name is present in variableTable. If no variable of that name is present in variableTable, inform the user there is no such variable.

· d (display): display the information of names and values of all the variables stored in variableTable.

#3. Submission: (i) Compress your entire Lab 3 folder into a zip file and upload it through Biola Canvas. (ii) Carefully fill out this self-evaluation report (no need for a peer review) and upload it through Biola Canvas.