Week 1 - Gemini

Question 1

What is the purpose of the #include<iostream> directive?

Answer 1

It tells the compiler and linker that the program will need to be linked to a library of routines that handle input from the keyboard and output to the screen (e.g.

Question 2

What is the using namespace std; directive used for?

Answer 2

The C++ standard divides names (like cin and cout) into subcollections called namespaces. This directive indicates that the program will use names defined in the std namespace (where iostream defines cout and cin). [cite: 67, 68, 69]

Question 3

What is the significance of the int main() function in a C++ program?

Answer 3

The main() function is the entry point of every C++ program; it’s the function called when the program is run. The execution of all C++ programs begins with the main function. [cite: 70, 71]

Question 4

What do the curly braces {} signify in the main() function (and other functions)?

Answer 4

The open brace { indicates the beginning of the function’s definition, and the closing brace } indicates its end. Everything between these braces is the function’s body. [cite: 72, 73]

Question 5

What does the return 0; statement in the main() function typically indicate?

Answer 5

It indicates that the program worked as expected without any errors during its execution. [cite: 74]

Question 6

What is cout in C++ and how is it used with the << operator?

Answer 6

cout identifies the standard character output device (usually the computer screen). The insertion operator << indicates that what follows is inserted into cout. [cite: 77, 79]

Question 7

How are statements separated in C++?

Answer 7

Statements are separated with an ending semicolon (;). [cite: 80]

Question 8

What does it mean that C++ is a ‘statically typed language’?

Answer 8

When you use a variable in C++, you must specify the type of data that will be stored in that variable, and once chosen, this type cannot be changed. [cite: 81, 82, 83]

Question 9

Why is it important to specify the data type of a variable in C++?

Answer 9

Data is stored in the computer as strings of 1s and 0s. Specifying the type tells the computer how to interpret these 1s and 0s (e.g., as binary numbers for integers, or character codes for chars). [cite: 85, 86]

Question 10

Define ‘bit’.

Answer 10

A single binary digit. [cite: 88]

Question 11

Define ‘byte’.

Answer 11

8 binary digits. [cite: 89]

Question 12

How many bytes are in a kilobyte (in the context of computer memory)?

Answer 12

$2^{10}$ or 1024 bytes. [cite: 89]

Question 13

How many bytes are in a megabyte (in the context of computer memory)?

Answer 13

$2^{20}$ or 1048576 bytes. [cite: 89]

Question 14

What is hexadecimal notation?

Answer 14

A base-16 number system using characters $0,1,2,3,…,9,A,B,…,F$. [cite: 90]

Question 15

What is a ‘variable’ in C++?

Answer 15

A symbolic name for storing information in memory. The value stored can be changed. Variables must be declared before use. [cite: 91, 93]

Question 16

What is the basic syntax for declaring a variable in C++?

Answer 16

Type_of_data Name_Variable; [cite: 94]

Question 17

List the built-in C++ data type for Boolean values and its keyword.

Answer 17

Boolean, bool [cite: 95, 97]

Question 18

List the built-in C++ data type for characters and its keyword.

Answer 18

Character, char [cite: 95]

Question 19

List the built-in C++ data type for integers and its keyword.

Answer 19

Integer, int [cite: 95]

Question 20

List the built-in C++ data types for floating-point numbers and their keywords.

Answer 20

Floating point, float; Double floating point, double [cite: 95]

Question 21

What values can a bool variable hold?

Answer 21

true or false. [cite: 97]

Question 22

How is a char data type stored in memory?

Answer 22

As a number between 0 and 255, taking up exactly one byte. [cite: 100]

Question 23

What is the ASCII code?

Answer 23

It associates an integer value for each symbol in the character set, allowing arithmetic operations on characters. For example, '9' - '0' evaluates to 9 because their ASCII values are 57 and 48 respectively. [cite: 102, 103]

Question 24

How does declaring a variable as char versus int affect input and output?

Answer 24

It makes an important difference to the type of input the program expects and the format of the output it produces. [cite: 104]

Question 25

Provide an example C++ code snippet to read a character and print its ASCII integer representation.

Answer 25

`int number; char character; cout<<"Type in a character: \\n"; cin>>character; number=(int)character; cout<<"The character is "<(character)`) [cite: 105, 106]

Question 26

Name some data-type specifiers for integers in C++ other than `int`.

Answer 26

`signed`, `unsigned`, `short`, `long`, `long long`. [cite: 108]

Question 27

What does the `unsigned` specifier mean for an integer type?

Answer 27

The variable is non-negative. This uses one less bit of memory that would otherwise be used for the sign. [cite: 111, 112]

Question 28

What is the `sizeof()` operator used for in C++?

Answer 28

To get the size (in bytes) of various data types. [cite: 113]

Question 29

Provide an example C++ code snippet to print the size of the `int` data type.

Answer 29

`cout << "Size of int : " << sizeof(int) << endl;` [cite: 114]

Question 30

What is 'casting' in C++?

Answer 30

Converting a value from one data type to another. [cite: 121]

Question 31

Why is casting sometimes necessary, for example, in division?

Answer 31

When dividing two `int` values, C++ performs integer division (e.g., $7/2$ is 3). To get a floating-point result (e.g., 3.5), one or both numbers must be treated as a floating-point type. If variables are used, casting is needed. [cite: 119]

Question 32

What is the C++ syntax for casting a variable `numerator` to `double` using `static_cast`?

Answer 32

`static_cast(numerator)` [cite: 122]

Question 33

What is the C-style cast syntax to convert `14.35` to an `int`?

Answer 33

`(int)(14.35)` (Note: `static_cast(14.35)` is preferred in modern C++) [cite: 125]

Question 34

What is the result of `double c = a/b;` if `int a = 3;` and `int b = 5;`? Why?

Answer 34

The result is 0. Because `a/b` is an integer division (3/5 = 0), and then 0 is cast to `double`. [cite: 127, 128, 130]

Question 35

How can you get the correct floating-point result (0.6) for `double c = a/b;` if `int a = 3;` and `int b = 5;`?

Answer 35

`double c = (static_cast(a))/b;` [cite: 131]

Question 36

What happens when casting a `double` to an `int`?

Answer 36

Information (the decimal part) is potentially lost. [cite: 132]

Question 37

What happens when casting a `bool` to an `int`?

Answer 37

`true` converts to 1, and `false` converts to 0. [cite: 135]

Question 38

What happens when casting an `int` to a `bool`?

Answer 38

Non-zero integers convert to `true`, and 0 converts to `false`. Information can be lost. [cite: 135]

Question 39

What happens when casting a `char` to an `int`?

Answer 39

Converts the character to the integer number used to represent that character on the system (e.g., its ASCII value). [cite: 136]

Question 40

How can you format `cout` to display floating-point numbers in fixed notation with a specific number of decimal places (e.g., 2)?

Answer 40

`cout.setf(ios::fixed); cout.precision(2);` [cite: 138, 139]

Question 41

How can you format `cout` to display floating-point numbers in scientific notation?

Answer 41

`cout.setf(ios::scientific);` [cite: 142]

Question 42

What is the `typedef` keyword used for in C++?

Answer 42

To assign an alternative name to a data type. For example, `typedef int Integer;` allows `Integer` to be used as a synonym for `int`. [cite: 144, 145]

Question 43

How can you initialize a variable at the same time as declaring it? Give an example.

Answer 43

`double PI = 3.1415926535;` [cite: 153]

Question 44

What is the `const` keyword used for in C++? Give an example.

Answer 44

To specify that a variable's value cannot be altered during program execution. Example: `const double PI = 3.1415926535;` [cite: 154, 155]

Question 45

What is an 'enumeration' (`enum`) in C++? Give an example.

Answer 45

It allows declaration of a set of named integer constants. Example: `enum {MON, TUES, WED, THURS, FRI, SAT, SUN};` This makes MON=0, TUES=1, etc. by default. [cite: 156, 157, 158]

Question 46

How can you assign specific integer values to members of an `enum` list?

Answer 46

`enum{ MON=1, TUES, WED, THURS, FRI, SAT=-1, SUN};` Uninitialized members take the value of the previous member plus one. [cite: 159, 160]

Question 47

What is the assignment operator in C++ and what does it do?

Answer 47

The `=` operator. It assigns a value to a variable. E.g., `x = 5;` or `x = y;`. [cite: 162, 163]

Question 48

If `x = y;` is executed, and then the value of `y` changes, does the value of `x` also change?

Answer 48

No, the change in `y` will not affect the new value taken by `x`. [cite: 165]

Question 49

What is the equivalent of `y = 2 + (x = 5);` as separate statements?

Answer 49

`x = 5; y = 2 + x;` [cite: 166]

Question 50

List the basic arithmetic operators in C++.

Answer 50

`+` (addition), `-` (subtraction), `*` (multiplication), `/` (division), `%` (modulo). [cite: 167]

Question 51

What does the modulo operator (`%`) do?

Answer 51

It gives the remainder of a division of two values. [cite: 167]

Question 52

What are compound assignment operators? Give an example.

Answer 52

Operators that modify the current value of a variable by performing an operation and then assigning the result to the first operand. Example: `y += x;` is equivalent to `y = y + x;`. Others include `-=`, `*=`, `/=`, `%=`. [cite: 168, 169, 170, 171]

Question 53

What do the increment (`++`) and decrement (`--`) operators do?

Answer 53

They increase or reduce the value stored in a variable by one. [cite: 172]

Question 54

What is the difference between prefix (`++x`) and postfix (`x++`) forms of the increment operator when used in an expression?

Answer 54

In prefix form, the increment is done *before* the rest of the expression is evaluated. In postfix form, the increment is done *after* the complete expression is evaluated. [cite: 174, 175, 176]

Question 55

If `x = 3; y = ++x;`, what are the values of `x` and `y`?

Answer 55

`x` contains 4, `y` contains 4. [cite: 177, 178]

Question 56

If `x = 3; y = x++;`, what are the values of `x` and `y`?

Answer 56

`x` contains 4, `y` contains 3. [cite: 177, 179]

Question 57

List the relational/comparison operators in C++.

Answer 57

`==` (equal to), `!=` (not equal to), `>` (greater than), `>=` (greater than or equal to), `<` (less than), `<=` (less than or equal to). [cite: 180]

Question 58

What are the logical operators in C++?

Answer 58

`&&` (logical AND), `||` (logical OR), `!` (logical NOT). [cite: 180]

Question 59

Explain the `&&` (logical AND) operator.

Answer 59

If both operands are non-zero (true), the condition becomes true. E.g., If A is 1 (true) and B is 0 (false), (A && B) is false. [cite: 181, 182]

Question 60

Explain the `||` (logical OR) operator.

Answer 60

If any of the two operands is non-zero (true), the condition becomes true. E.g., If A is 1 (true) and B is 0 (false), (A || B) is true. [cite: 183, 184]

Question 61

Explain the `!` (logical NOT) operator.

Answer 61

It reverses the logical state of its operand. If a condition is true, `!` makes it false. E.g., If A is 1 (true) and B is 0 (false), !(A && B) is true (since A&&B is false). !(A||B) is false. [cite: 185, 186, 187]

Question 62

What is the precedence of `&&` versus `||`? Which one is evaluated first in an unparenthesized expression?

Answer 62

`&&` has higher precedence than `||` (similar to `*` and `+`). If in doubt, use parentheses. [cite: 191, 192]

Question 63

What is the conditional ternary operator (`? :`) and its syntax?

Answer 63

It evaluates an expression, returning one value if true and another if false. Syntax: `condition ? result1 : result2`. [cite: 195, 196]

Question 64

How can you use the conditional ternary operator to find the maximum of two integers `a` and `b` and store it in `max_val`?

Answer 64

`int max_val = ((a > b) ? a : b);` [cite: 197]

Question 65

What does the bitwise operator `<<` do? Give an example.

Answer 65

Shifts all bits in a number to the left by a given amount. `x << 3` shifts all bits in `x` three places to the left. [cite: 200, 201]

Question 66

What does the bitwise operator `>>` do? Give an example.

Answer 66

Shifts all bits in a number to the right by a given amount. `x >> 3` shifts all bits in `x` three places to the right. [cite: 202, 203]

Question 67

What does the bitwise AND operator `&` do?

Answer 67

The n-th bit of `a&b` is 1 if the corresponding bit of `a` is 1 AND the corresponding bit of `b` is 1. [cite: 204, 205]

Question 68

What does the bitwise OR operator `|` do?

Answer 68

The n-th bit of `a|b` is 1 if the corresponding bit of `a` is 1 OR the corresponding bit of `b` is 1. [cite: 206]

Question 69

How do you write a C++ program to print the lines: 'You are a student.' and 'You are learning C++.' on separate lines? (Sheet 1, Prelim Q1)

Answer 69

`#include\nusing namespace std;\nint main() {\n cout << "You are a student.\\n";\n cout << "You are learning C++.\\n";\n return 0;\n}` (The exercise output implies separate `cout` statements or `endl`) [cite: 3]

Question 70

How do you declare two integer variables and one float variable, assign 10, 15, and 12.6 to them respectively, and print their values? (Sheet 1, Prelim Q2)

Answer 70

`#include\nusing namespace std;\nint main() {\n int intVar1 = 10;\n int intVar2 = 15;\n float floatVar = 12.6f; // 'f' suffix for float literal is good practice\n cout << intVar1 << endl;\n cout << intVar2 << endl;\n cout << floatVar << endl;\n return 0;\n}` [cite: 4, 5]

Question 71

How do you prompt the user to input 3 integer values and then print these values in forward and reversed order? (Sheet 1, Prelim Q3)

Answer 71

`#include\nusing namespace std;\nint main() {\n int n1, n2, n3;\n cout << "Please enter your 3 numbers: ";\n cin >> n1 >> n2 >> n3;\n cout << "Your numbers forward:\\n" << n1 << "\\n" << n2 << "\\n" << n3 << "\\n";\n cout << "Your numbers reversed:\\n" << n3 << "\\n" << n2 << "\\n" << n1 << "\\n";\n return 0;\n}` [cite: 6, 7]

Question 72

How do you declare 3 integer variables, assign 10 and 15 to the first two, assign their product to the third, and print all three? (Sheet 1, Prelim Q4)

Answer 72

`#include\nusing namespace std;\nint main() {\n int val1 = 10;\n int val2 = 15;\n int product = val1 * val2;\n cout << val1 << endl;\n cout << val2 << endl;\n cout << product << endl;\n return 0;\n}` [cite: 8, 10]

Question 73

How do you write a C++ program to print the number of bytes used by five different basic data types (e.g., char, int, float, double, bool)? (Sheet 1, Basic Data Types Q1)

Answer 73

`#include\nusing namespace std;\nint main() {\n cout << "Size of char: " << sizeof(char) << " bytes\\n";\n cout << "Size of int: " << sizeof(int) << " bytes\\n";\n cout << "Size of float: " << sizeof(float) << " bytes\\n";\n cout << "Size of double: " << sizeof(double) << " bytes\\n";\n cout << "Size of bool: " << sizeof(bool) << " bytes\\n";\n // Try other combinations like short, long, unsigned int\n cout << "Size of short int: " << sizeof(short int) << " bytes\\n";\n cout << "Size of long int: " << sizeof(long int) << " bytes\\n";\n cout << "Size of unsigned int: " << sizeof(unsigned int) << " bytes\\n";\n return 0;\n}` [cite: 12, 13, 114]

Question 74

How do you cast `char` values to `int` to find the ASCII codes for characters like 'a', 'z', 'A', 'Z', '0', '9'? (Sheet 1, Basic Data Types Q2)

Answer 74

`#include\nusing namespace std;\nint main() {\n char c1 = 'a', c2 = 'z', c3 = 'A', c4 = 'Z', c5 = '0', c6 = '9';\n cout << "ASCII for 'a': " << static_cast(c1) << endl;\n cout << "ASCII for 'z': " << static_cast(c2) << endl;\n cout << "ASCII for 'A': " << static_cast(c3) << endl;\n cout << "ASCII for 'Z': " << static_cast(c4) << endl;\n cout << "ASCII for '0': " << static_cast(c5) << endl;\n cout << "ASCII for '9': " << static_cast(c6) << endl;\n return 0;\n}` (Based on problem description and lecture content [cite: 102, 105, 122, 136]) [cite: 13]

Question 75

Outline the logic for a program that reads a character and displays if it's a lowercase letter (and its uppercase), an uppercase letter (and its lowercase), or not a letter. (Sheet 1, Basic Data Types Q3)

Answer 75

1. Read a character `ch`.\n2. Check if `ch >= 'a' && ch <= 'z'` (lowercase).\n If true, print `ch` and `static_cast(ch - 'a' + 'A')`.\n3. Else, check if `ch >= 'A' && ch <= 'Z'` (uppercase).\n If true, print `ch` and `static_cast(ch - 'A' + 'a')`.\n4. Else, print `ch` is not a letter. (This uses knowledge of ASCII values being contiguous for letters) [cite: 14, 102, 103]

Question 76

What is a compiled language?

Answer 76

Compiled languages are translated to the target machine's native language by a program called a compiler, resulting in very fast code. C++ is an example. [cite: 38, 39]

Question 77

What is an interpreted language?

Answer 77

Interpreted languages (e.g., R, Matlab, Python) are read by a program called an interpreter and are executed by that program. They are usually much slower than compiled programs. [cite: 39, 40]

Question 78

What is the general structure of the first 'Hello world!' C++ program?

Answer 78

`#include\nusing namespace std;\nint main()\n{\n cout << "Hello world!";\n return 0;\n}` [cite: 62, 63]

Question 79

Can you do arithmetic with `char` types in C++? Explain.

Answer 79

Yes, because `char` types are stored as numbers (ASCII codes). For example, `'9' - '0'` would result in the integer 9. [cite: 102, 103]

Question 80

What is meant by initializing a variable?

Answer 80

Assigning an initial value to a variable at the time of its declaration or before its first use. [cite: 152, 153]

Question 81

What is the difference between `cout.setf(ios::fixed);` and `cout.setf(ios::scientific);`?

Answer 81

`ios::fixed` forces output of floating-point numbers in fixed decimal format (e.g., 123.45). `ios::scientific` forces output in scientific notation (e.g., $1.2345e+02$). [cite: 138, 142]

Question 82

What is the typical range of values you can store in an `int` variable?

Answer 82

Guaranteed to store values between $-2^{31}$ and $2^{31}-1$. [cite: 110]

Question 83

What is the typical range of values you can store in a `long long` variable?

Answer 83

Guaranteed to store values between $-2^{63}$ and $2^{63}-1$. [cite: 110]

Question 84

What are comments in C++ and how are they denoted?

Answer 84

Comments are notes for human readers that are ignored by the compiler. Single-line comments start with `//`. Multi-line comments start with `/*` and end with `*/`.

Question 85

What does the `` header file provide?

Answer 85

It provides standard mathematical functions like `sqrt()` (square root), `pow()` (power), trigonometric functions, etc.

Question 86

What does `cin` represent in C++?

Answer 86

It represents the standard input stream, typically the keyboard. It's used with the extraction operator `>>` to read input.