CMSC 202 Exam 1

Logical operators

&& [and] || [or] ! [not]; and, or has less precendence than not; part of flow of control

Null terminator

'/0'; used in c-string initialization to indicate the end of a c-string

Comparison operators

(==, !=) has less precedence over (>, <, >=, <=); part of flow of control

Ternary operator

(x > y ? x : y) If x greater than y, then x. else, y. Simplified syntax for if statements; part of flow of control

<fstream> commands

.open(filename); to read, use inputStream >> var; .close(filename)

Assignment operators

=, +=, -=, *=, /=, %=; has less precedence to comparison and logical; part of flow of control

Pass by value parameters

A copy of the original variable is made inside function and it is only changed inside of the function's local scope. If returned, copy is sent back to main(), else, it will die in the function

Void function

A function that does not return anything

Class

A group of objects with similar properties and behaviors. Has states/attributes (variables) and behaviors (methods). Automatically private unless changed.

Memory address

A hexademical value

Variable

A memory location to store data

If statements

A statement that executes based on the condition (boolean). If one statement in the entire thing, no need for braces; part of flow of control

Array indexing

Access elements in array using indices; array[2]

Function prototype

Also called function declaration, includes function name, parameters, and return type. Place above main().

C-string

An array of characters; works like an array in general

Object

An instance of a class

While loop

As long as condition is true, loop will run. Can run from 0 to infinity times. Condition is checked before the body is executed

Do-while loop

Can run 1 to infinity times. Condition is checked after the body (do-part) is executed.

Constants

Cannot change values during execution. All data types can be made into constants

Switch statement

Controls multiple branches, does same thing as if statements but more convienent. Controlling expression must return boolean values

Post-condition of function

Details what the function is expected to return/do if executed

Cout-ing Void functions

Do not cout void functions because they do not return anything

Preprocessor directive

Executes before the compiler and simply copies library files to your file

Pointers as function parameters

Functions can be void when passing in pointers

Function overloading

Functions that complete similar tasks, have same name but different parameter lists. Based on function signatures (parameters must be in same order)

<iostream>

Holds cin, cout, cerr. Part of preprocessor directives.

Data type: boolean

Holds up to 1 byte. True (1) or False (0)

Data type: character

Holds up to 1 byte. Use single quotes

Data type: integer

Holds up to 4 bytes

Data type: float

Holds up to 4 bytes. Can have precision set to 7 decimal places

Data type: double

Holds up to 8 bytes. Can have precision set to 15 decimal places

Displaying output: floating-points

If floating-point results in .0, output will only show whole number, not the decimals.

cin.clear()

If the input that is being tested through cin.fail() does not match the declared date type, cin.clear() function then clears the input.

Function signature

Includes function name and the order of parameters. No return type.

<iomanip>

Input output manipulator. Holds setw(), cout.fill(), setprecision()

Setw()

Sets field width to n

Break statement

Terminates a loop. Must be used in switch statements

Array memory address

The first element of an array is the array's memory address

Function definition

The implementation of the code (the actual body). Place under main().

Indentifier

The name of the variable, function, class, structure, etc. Case-sensitive, camel-case, do not use keywords like int.

Pass by reference parameters

Use & before parameter name. Original value of variable will change permanently in the function. int &money;

Deferencing pointer

Use * again for the already declared pointer to get the value of variable it is pointing at.

Pointer intialization

Use * to declare pointer, and assign it with a variable's address. Pointer type must match variable type. int *ptr = &x

Initializing a variable

Use an assignment operator

getline(cin, variable)

Used to take the whole length of an input when using cin. Assigns that input to cin. another ex: cin.getline(char, 80) <-- char[80] char array of size 80

Literals

Values that were literally typed in.

Overloading resolution

When user program runs and finds overloaded functions being called. 1st: exact match, no argument conversion required 2nd: compatible match; looks for most compatible signature and does automatic type conversion

Escape sequences

\n, \t, \\, \"

Array

a collection of related data items. Allocates memory addresses for the data. int array[size];

Class name and methods

always begin with capital letter

Default argument

an argument that is passed automatically to a parameter if the argument is missing on the function call. Only found in function prototype; must be at the end of the list of parameters.

Multi-dimensional array

an array that uses more than one index to specify a stored value. 2d_array[x][y]

Access specifier type: public

anything that has access to the object has access to all public member variables and functions. Have at least one public member

Access specifier type: protected

can only be accessed by member functions of the class.

Using pointers for c-strings

char *word is another way to pass a c-string because c-strings are arrays, and arrays are like pointers (they hold memory addresses).

Namespace

collection of name definitions

Structure

collection of values of different types, no memory is allocated, define struct as global variable. Has member variables and a semicolon at the end. Automatically public

strcmp()

compares two c-strings

Debugging methods

cout statements, compiler debugger, stubs and drivers

Scope

curly braces define scope

Pre-condition of function

details what is required for the function to work properly

cin.fail()

determines whether the current input variable matches the declared data type. Combine with cin.clear()

Stubs

each function is designed, coded, and tested separately. ensures validity of each unit. Develop incrementally. Combine techniques with a driver

Comma operator

evaluates list of expressions, returns the value of the last expression. mostly used in for-loops

For loop

executes an explicit number of times. For (int i = 0; i > 3; i++)

<fstream>

file stream, handles data being read from a file as input. declare input stream: ifstream inputStream;

Input stream

flow of bytes from the device to main memory (i.e. keyboard)

Output stream

flow of bytes from the memory to the device (i.e. screen)

Setprecision()

formats floating-point data types. Will show n number of decimal places. Two ways: cout << setprecision(n) OR cout.precision(n)

Argument

function(argument); refers to function calls

Parameter

function(parameter); refers to function prototype

<ctime>

has time(); use time(NULL) to get current computer time. Can use for srand()

Libraries

holds the commands for certain commands. Are preprocessor directives

Parts of a variable

identifier, memory address, value of the variable, and its scope

<cstdlib>

includes srand(), rand()

Protecting pass by reference parameters

make the original variable passed as a constant

Arrays as function parameters

must put array type, and array size

Struct and Class data

must start member variables names with m_

Separate file compilation

once classes are defined, separate into a header file and cpp file.

Array length

program does not array length, so user must get the length of array so it will not go out bounds.

Auto-initialization

program will automatically allocate space for an array size even if the user does not declare it explicity. int arr = {2, 3}; has size of 2.

Automatic type conversion

promotes or demotes variable types. Promotion results in no data loss while demotion might. Promotion: int, float, char --> double Demotion: double --> int, float

Cerr

provides mechanism for distinguishing between regular output and error output. Works like cout

cin.peek()

returns next character without removing

Sizeof()

returns the size of a variable. can be used to find size of an array (in data bytes)

Random number geenrator (RNG)

seed randomizer using srand() once, then can call rand(). rand() % 1; (0-1 range)

Abstraction

separates code use from code implementation; cin is a command you can use but you do not know the code behind it.

cout.fill(c)

sets "fill" character to c

Scope resolution operator for classes

specifies which class the function belongs to Class::myFunction()

Encapsulation

the hiding of implementation details; data and functions that are located in a class is considered the encapsulation. protects data

cin.ignore(number, character)

this funtion tells the cin object to skip characters in the keyboard buffer. ex: cin.ignore(256, '\n') ignores 256 characters until it finds a new line

makeFile for classes

to compile each class, add rules to makeFile to combine the separated files

Return statement

transfer control back to the calling function i.e. main() most times; required for all types of functions except void; multiple returns can be used

Pointer

type of variable whose value is a memory address

Dot operator

used to access member variables and methods.

Driver

used to test code independently

Cin

uses extraction operator >>. No literals for cin, must be a variable

Cout

uses insertion operator <<

Arrays as function arguments

using single element as argument, element is passed by value. Using whole array as argument, array is passed by reference

Local scope

variables live and die inside of their corresponding function