C++ Review Sheet
in CS 102 on C++, Programming Basics
C++ review sheet, updated as of 03/21/2019
This review sheet will cover the following topics:
- Basics - Mon, Jan. 28; Q1 Wed, Feb. 06
- Data Types - Wed, Jan. 30; Q1 Wed, Feb. 06
- Arithmetic - Mon, Feb. 04; Q1 Wed, Feb. 06
- Conditionals - Mon, Feb. 11; CA1
- Loops - Wed, Feb. 20, Mon, Feb. 25; A1
- Strings - Wed, Feb. 20, Mon, Feb. 25; A1
- Functions - Wed, Mar. 21
- Scope - Wed, Apr. 3
- Recursion - Wed, Mar. 21; TB-Continued
- Arrays - Wed, Apr. 3
- Vectors - Wed, Apr. 3
- Pseudorandom Numbers - Wed, Feb. 11
- Pass By Reference/Value
- Structs - Mon, Apr. 22
Basics
//This is a comment
/*
This is a multiline comment
*/
#include <iostream>
using namespace std;
int main() {
cout << "Hello World!" << endl;
return 0;
}
Data Types
#include <iostream>
using namespace std;
int main() {
// int is an integer value: 0, 1, 2, 3, ...
int myAge = 35;
// const values cannot be changed
const double PI = 3.14;
// char is a letter denoted in single quotes: 'a', 'b', 'c', ...
char myGrade = 'A';
// bool is either true (1) or false (0)
bool isHappy = true;
// float are numbers with max 7 sig figs
float favFloat = 3.141592;
// double has 2x precision of a float, max 16 sig figs
double favDouble = 3.312141592341213;
cout << "Printing the number " << PI << endl;
/* Other types include:
short int: >= 16 bits
long int: >= 32 bits
long long int: >= 64 bits;
unsigned int: same size as signed int
long double >= double
*/
cout << "Size of int: " << sizeof(myAge) << " bytes." << endl;
cout << "Size of double: " << sizeof(favDouble) << " bytes." << endl;
cout << "Size of float: " << sizeof(favFloat) << " bytes." << endl;
cout << "Size of bool: " << sizeof(isHappy) << " bytes." << endl;
cout << "Size of char: " << sizeof(myGrade) << " bytes." << endl;
int largestInt = 2147483647; // also written as INT_MAX
cout << "Largest int possible: " << largestInt << endl;
int smallestInt = -2147483648; // also written as INT_MIN
cout << "Smallest int possible: " << smallestInt << endl;
/* Why is the smallest integer value just the negation of the largest integer?
In two's complement (a representation for positive and negative binary numbers), the leftmost
bit is reserved for the sign (+ or -). If a number is negative, the leftmost bit will be 1.
If positive, the leftmost bit is 0.
In a fixed-size representation of 3 bits (with signed numbers, aka Two's Complement),
the most negative value is the binary number 100 ( = 4). The largest number is 011 ( = 3).
For the fixed-size representation of any number of bits (which I name 'x'),
the largest number is 2^(x-1) -1. The smallest value (or the most negative value) is -1 * 2^(x-1)
or just one less than the largest number.
*/
return 0;
}
To read more about number systems and binary representations, see: CS 101 Notes on Binary
Arithmetic
#include <iostream>
using namespace std;
int main() {
/* MATH OPERATIONS include:
+ addition
- subtraction
* multiplication
/ division
% modulus
++ increment by 1 aka add 1
-- decrement by 1 aka subtract 1
*/
cout << "5 + 2 = " << 5 + 2 << endl;
cout << "5 - 2 = " << 5 - 2 << endl;
cout << "5 * 2 = " << 5 * 2 << endl;
cout << "5 / 2 = " << 5 / 2 << endl;
cout << "5 % 2 = " << 5 % 2 << endl;
int num = 5;
cout << "5++ = " << num++ << endl; // shows '5', then increments by 1; num = 6
cout << "++5 = " << ++num << endl; // increments by 1, then shows 7; num = 7
cout << "5-- = " << num-- << endl; // shows '7', then decrements by 1; num = 6
cout << "--5 = " << --num << endl; // decrements by 1, then shows '5'; num = 5
num += 10; // num = num + 10;
// consider the ORDER OF OPERATIONS: * and / execute first, then + and -
cout << "1 + 2 - 3 * 2 = " << 1 + 2 - 3 * 2 << endl; // = -3
cout << "(1 + 2 - 3) * 2 = " << (1 + 2 - 3) * 2 << endl; // = 0
// CASTING changes the data type
cout << "4 / 5 = " << 4 / 5 << endl; // returns 0 because an int / int = int
cout << "4 / 5 = " << (double) 4 / 5 << endl; // returns 0.8 because double / int = double
cout << "4 / 5 = " << (double) 4 / (double) 5 << endl; // returns 0.8 because double / double = double
// generating RANDOM numbers
int randNum0To99 = (rand() % 100); //random number between 0 and 99
int randNum1To100 = (rand() % 100) + 1; //random number between 1 and 100
cout << "Random # between 1 and 100: " << randNum1To100 << endl;
return 0;
}
Conditionals
#include <iostream>
using namespace std;
int main() {
// CONDITIONALS (aka BRANCHES) execute different code depending on the conditions
/* COMPARISON OPERATORS
== is it equal?
!= is it not equal?
> is it greater than?
< is it less than?
>= is it greater than or equal to?
<= is it less than or equal to?
*/
bool canBeWalked = false;
bool isLazy = true;
if (canBeWalked){ // is false, doesn't print anything, goes to next statement
cout << "The animal is a dog." << endl;
} else if (isLazy) { // this statement is true, prints '... is a cat'
cout << "The animal is a cat." << endl;
} else { // this statement is not checked because the prev. is already true.
cout << "The animal is a fish." << endl;
}
canBeWalked = true;
if (isLazy){ // is true. Check next statement because it is not an 'else'
cout << "The animal is a cat." << endl;
}
if (canBeWalked){ // is also true.
cout << "The animal is a dog." << endl;
}
/* LOGICAL OPERATORS
&& AND are both true?
|| OR is either true?
! NOT is it not true?
*/
int age = 70;
int ageAtLastExam = 16;
bool isIntoxicated = false;
if ((age >= 1) && (age < 16)){ // if age is between 1 (inclusive) AND 16 (exclusive)
cout << "You cannot drive." << endl;
} else if (isIntoxicated) { // if you are intoxicated
cout << "You cannot drive." << endl;
} else if (age >= 80 && ((age > 100) || (age - ageAtLastExam) > 5)){
// if you are older than 100 OR
// if you haven't take the exam in the last 5 years
// if either of the above conditions are true AND you are 80 or older, you can't drive
cout << "You cannot drive." << endl;
} else { // when none of the previous conditions are not met, you can drive
cout << "You can drive." << endl;
}
int bookOption = 2;
switch(bookOption){ // evaluates an INT EXPRESSION, not a BOOLEAN EXPRESSION
case 1:
cout << "Harry Potter" << endl;
break; // if bookOption == 1, don't check the other cases.
case 2:
cout << "The Hunger Games" << endl;
break; // bookOption equals 2, exit switch statement.
case 3:
cout << "Frankenstein" << endl;
break;
default: // if no cases are true
cout << "Computer Science textbook" << endl;
}
switch(1) {
case 1 :
cout << '1'; // prints "1",
case 2 :
cout << '2'; // then prints "2"
}
switch(1) {
case 1 :
cout << '1'; // prints "1"
break; // and exits the switch
case 2 :
cout << '2';
break;
}
/* TERNARY OPERATOR
variable = (condition) ? true : false
*/
int largestNum = (5 > 2) ? 5 : 2;
/* ORDER OF EVALUATION
1. ( ) parentheses
2. ! NOT
3. */% division, multiplication, modulus
4. +- addition, subtraction
5. < <= > > = comparison operators
6. == != equality operators
7. && AND
8. || OR
*/
return 0;
}
Loops
#include <iostream>
using namespace std;
int main() {
// a FOR LOOP that counts from 0 to 25
for (int i = 0; i <= 25; i++){
cout << i << " ";
} cout << endl;
// The WHILE LOOP that generates random numbers until a random number equals 10
while (randNum != 10){
cout << randNum << " is not equal to 10." << endl;
randNum = (rand() % 10) + 1; //regenerate a random number
} cout << "Random number equals 10. Exiting loop." << endl;
int index = 0;
while (index <= 25){ // will simulate a FOR loop counting to 25
cout << index << " ";
index++;
} cout << endl;
// a DO WHILE LOOP that plays a guessing game with the user until the user guess the correct number
string numberGuessed; // a STRING is a series of chars
int intNumberGuessed = 0;
do {
cout << "Guess a number between 1 and 10: ";
getline(cin, numberGuessed); // get USER INPUT and store it into variable numberGuessed
intNumberGuessed = stoi(numberGuessed); // convert string to int with stoi
} while (intNumberGuessed != 4);
cout << "You guessed the correct number!" << endl;
return 0;
}
Strings
#include <iostream>
#include <string> // this include statements tells the preprocessor to get the file containing the relevant string functions
using namespace std;
int main() {
string myDogFirstName = "Fluffy";
string myDogLastName = "Marie Alfonso James";
string myDogSuffix = "Jr. III";
// combine or CONCATENATE strings with +
cout << "My dog's name is " << myDogFirstName + " " + myDogLastName + " " + myDogSuffix << endl;
// getting and storing USER INPUT
string yourName;
cout << "What is your name? ";
getline(cin, yourName);
cout << "Hello " + yourName + "!" << endl;
// converting string to other data types
double fivePIdigits = 3.1415;
string piGuess;
double piGuessDouble;
cout << "What are the digits of pi? ";
getline(cin, piGuess);
piGuessDouble = stod(piGuess); //convert string to double with stod
if (piGuessDouble == fivePIdigits){
cout << "You are right." << endl;
} else {
cout << "You are wrong." << endl;
}
// other functions of the string class
cout << "Size of string " << piGuess.size() << endl; //returns # of chars
cout << "Is the string empty? " << piGuess.empty() << endl; //returns 0 if empty, 1 if not.
cout << piGuess.append( " was your guess.") << endl; // appends to end of string
string alpha = "alpha";
string beta = "beta";
cout << "Alpha < Beta denoted as " << alpha.compare(beta) << endl; // returns -1; in alphabetic order, 'alpha' comes before 'beta'
cout << "Alpha == Alpha denotes as: " << alpha.compare(alpha) << endl; // returns 0; 'alpha' is equal to 'alpha'
cout << "Beta > Alpha denoted as: " << beta.compare(alpha) << endl; // returns 1; in alphabetic order, 'alpha' comes after 'beta'
string wholeName = yourName.assign(yourName);
cout << "Your whole name is: " + wholeName << endl;
string firstName = wholeName.assign(wholeName, 2, 5); // grabs 5 characters from index 2; 'becca' from 'Rebecca'
cout << "Your first name is: " + firstName << endl;
int lastNameIndex = yourName.find("Ramnauth", 0); // search for 'Ramnauth' in yourName starting at index 0
cout << "Index of last name: " << lastNameIndex << endl;
yourName.insert(7, " Ann Marie");
cout << "Your new name is " + yourName << endl;
yourName.erase(8, 4); // delete 4 characters starting at 8th char
cout << "Your new name is " + yourName << endl;
yourName.replace(14, 8, "Robins"); // replace 8 characters starting at 14th char with 'Robins'
cout << "Your new name is " + yourName << endl;
return 0;
}
In the case you want to ignore all escape characters, use the following methods for getting raw-input.
#include <iostream>
#include <string>
using namespace std;
int main(){
// Method 1: using '\\' instead of '\'
cout << " ============================================== " << endl;
cout << " ___ ___ _ __ ___ __ __ ___ _ _ " << endl;
cout << " | _ \\ / _ \\ | |/ / | __|| \\/ | / _ \\ | \\| | " << endl;
cout << " | _/| (_) || ' < | _| | |\\/| || (_) || .` | " << endl;
cout << " |_| \\___/ |_|\\_\\ |___||_|__|_| \\___/ |_|\\_| " << endl;
cout << " ============================================== " << endl;
// Method 2: using raw string literals
cout << R"( ============================================== )" << endl;
cout << R"( ___ ___ _ __ ___ __ __ ___ _ _ )" << endl;
cout << R"( | _ \ / _ \ | |/ / | __|| \/ | / _ \ | \| | )" << endl;
cout << R"( | _/| (_) || ' < | _| | |\/| || (_) || .` | )" << endl;
cout << R"( |_| \___/ |_|\_\ |___||_|__|_| \___/ |_|\_| )" << endl;
cout << R"( ============================================== )" << endl;
return 0;
}
Functions
#include <iostream>
#include <cmath>
#include <string>
using namespace std;
int addNumbers(int a, int b) {
int sum = a + b;
return sum;
}
int addNumbers(int c, int d, int f) { // overloading addNumbers() -- two functions have the same name, but different parameters
int sum = c + d + f;
return sum;
}
int multiplyNumbers(int a, int b) {
int product = a * b;
return product;
}
int subtractNumbers(int a, int b) {
int result = a - b;
return result;
}
int divideNumbers(int a, int b) {
if (b != 0) { //cannot divide by 0
cout << "Divide by 0 error." << endl;
return -21312; //you have to return an integer.
} else {
int quotient = a / b;
return quotient;
}
}
int showMenu(){
cout << "Choose which option you'd like to perform: " << endl;
cout << "1. Add 2 integers" << endl;
cout << "2. Add 3 integers" << endl;
cout << "3. Subtract 2 integers" << endl;
cout << "4. Multiply 2 integers" << endl;
cout << "5. Divide 2 integers" << endl;
int choice;
cin >> choice;
return choice;
}
int enterNumber(){
cout << "Enter a number: ";
int num;
cin >> num;
return num;
}
int main(){
cout << "----------------------------" << endl;
cout << " CALCULATOR " << endl;
cout << "----------------------------" << endl;
int x, y, z; //declare 3 variables
int operation = showMenu();
switch(operation){
case 1: // add 2 numbers (x and y)
x = enterNumber();
y = enterNumber();
cout << x << " + " << y << " = " << addNumbers(x, y) << endl;
break;
case 2: // add 3 numbers (x, y, and z)
x = enterNumber();
y = enterNumber();
z = enterNumber();
cout << x << " + " << y << " + " << z << " = " << addNumbers(x, y, z) << endl;
break;
case 3: // subtract 2 numbers
x = enterNumber();
y = enterNumber();
cout << x << " - " << y << " = " << subtractNumbers(x, y) << endl;
break;
case 4: // multiply 2 numbers
x = enterNumber();
y = enterNumber();
cout << x << " * " << y << " = " << multiplyNumbers(x, y) << endl;
break;
case 5: // divide 2 numbers
x = enterNumber();
y = enterNumber();
cout << x << " / " << y << " = " << divideNumbers(x, y) << endl;
break;
default:
cout << "You did not enter a valid menu choice. Try again." << endl;
showMenu();
}
return 0;
/* Example output:
Choose which option you'd like to perform:
1. Add 2 integers
2. Add 3 integers
3. Subtract 2 integers
4. Multiply 2 integers
5. Divide 2 integers
2
Enter a number: 4
Enter a number: 5
Enter a number: 4
4 + 5 + 4 = 13
*/
}
Scope
#include <iostream>
using namespace std;
int x = 10;
int main() {
int x = 4;
cout << "Global x = " << ::x << endl;
cout << "Local x = " << x << endl;
return 0;
}
#include <iostream>
using namespace std;
int x = 10; // global
int addNumbers(int x, int y) {
return x + y; // local
}
int incrementNumber(int num) {
return num + 1; // local
}
int main() {
int y = 5; // local
y = incrementNumber(y);
cout << addNumbers(x, y);
return 0;
}
Recursion
#include <iostream>
using namespace std;
int getFactorial(int number); // does not recurse to get factorial of a number
int getFactorialRecursively(int number); // recurses to get factorial of a number
int main() {
cout << "8! = " << getFactorial(8) << endl;
cout << "5! = " << getFactorial(5) << endl;
cout << "0! = " << getFactorial(0) << endl;
cout << "8! = " << getFactorialRecursively(8) << endl;
cout << "5! = " << getFactorialRecursively(5) << endl;
cout << "0! = " << getFactorialRecursively(0) << endl;
return 0;
}
int getFactorial(int number){
int num = number; //just storing param for safekeeping
int factorial = 1;
while(num > 0){
factorial = factorial * num;
num--;
}
return factorial;
}
int getFactorialRecursively(int number){
int factorial;
if (number == 1) // this base case tells the recursive function when to stop
factorial = 1;
else
factorial = getFactorial(number - 1) * number; // recursive because it calls itself
return factorial;
/* behind the scenes of getFactorialRecursively(5):
getFactorialRecursively(5) --> else statement --> getFactorialRecursively(4) * 5
getFactorialRecursively(4) --> else statement --> getFactorialRecursively(3) * 4
getFactorialRecursively(3) --> else statement --> getFactorialRecursively(2) * 3
getFactorialRecursively(2) --> else statement --> getFactorialRecursively(1) * 2
getFactorialRecursively(1) --> if statement --> 1
Now we know:
getFactorialRecursively(2) = getFactorialRecursively(1) * 2 = 1 * 2
getFactorialRecursively(3) = getFactorialRecursively(2) * 3 = 1 * 2 * 3
getFactorialRecursively(4) = getFactorialRecursively(3) * 4 = 1 * 2 * 3 * 4
getFactorialRecursively(5) = getFactorialRecursively(4) * 5 = 1 * 2 * 3 * 4 * 5
Therefore:
getFactorialRecursively(5) = 1 * 2 * 3 * 4 * 5 = 120
*/
}
Arrays
#include <iostream>
using namespace std;
int main() {
cout << "-----------------------------------" << endl;
cout << " ARRAYS " << endl;
cout << "-----------------------------------" << endl;
// arrays store multiple values of the same data type, like baskets
int luckyNums[5]; // says that this "basket" called luckyNums can hold only 5 integers
int unluckyNums[5] = {4, 6, 1, 9, 78}; // these are the integers in my "basket" called unluckyNums
cout << "First unlucky number = " << unluckyNums[0] << endl;
cout << "Second unlucky number = " << unluckyNums[1] << endl;
cout << "Last unlucky number = " << unluckyNums[4] << endl;
// MULTIDIMENSIONAL ARRAYS means baskets of baskets
char name[2][5] = {
{'B', 'e', 'c', 'k', 'y'},
{'R', 'a', 'm', 'e', 'n'}
};
// name[index of which row?][index of which column?]
cout << "2nd letter in the 2nd array: " << name[1][1] << endl;
cout << "1st letter in the 1st array: " << name[0][0] << endl;
cout << "Last letter in the last array: " << name[1][4] << endl;
name[0][4] = 'i'; // changing last letter of first array to 'i'
cout << "Last letter in the 1st array: " << name[0][4] << endl;
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 5; j++) {
cout << name[i][j];
}
cout << " ";
}
return 0;
}
Vectors
#include <iostream>
using namespace std;
int main() {
cout << "-----------------------------------" << endl;
cout << " VECTORS " << endl;
cout << "-----------------------------------" << endl;
// just like arrays, except their size could change
vector <int> lotteryNumVect(10); // initializes vector with 10 zeros
int lotteryNumArray[5] = {4, 13, 14, 24, 34};
// at the beginning of vector, insert elements 0, 1, and 2 of array
lotteryNumVect.insert(lotteryNumVect.begin(), lotteryNumArray, lotteryNumArray+3);
for (int i = 0; i < lotteryNumVect.size(); i++){
cout << "Value at index " << i << " = " << lotteryNumVect.at(i) << endl;
}
lotteryNumVect.insert(lotteryNumVect.begin()+5, 44); //add number 44 to vector at index 5
cout << "Item at index 5 = " << lotteryNumVect.at(5) << endl;
lotteryNumVect.push_back(64); // insert number 64 to the end of the vector
cout << "Last value = " << lotteryNumVect.back() << endl; // get last/back element
cout << "First value = " << lotteryNumVect.front() << endl; // get first/front element
cout << "Is the vector empty? " << lotteryNumVect.empty() << endl; // returns an int (0 = false, 1 = true)
cout << "Size of vector = " << lotteryNumVect.size() << endl; // how many elements?
lotteryNumVect.pop_back(); // removes last element
cout << "New size of vector = " << lotteryNumVect.size() << endl; // size has decreased by 1
return 0;
}
Psuedorandom Numbers
#include<iostream>
#include<cstdlib>
#include <math.h>
#include <vector>
using namespace std;
int notSoRandomNum(){
srand(0); // set the seed of the pseudo random algorithm to 0
return rand() % 100 + 1; // always returns 84
}
int stillNotSoRandomNum(){
srand(1); // set the seed to 1
return rand() % 100 + 1; // always returns 84
}
int kindaRandomNum(){
return rand() % 100 + 1; // returns the same numbers each time (87, 78, 16, 94, 36)
}
int lilBetterRandomNum(){
srand(time(0)); // use the current time as the seed
return rand() % 100 + 1; // executes so fast that it really uses the same seed, but different each time you run the program
}
int notBetterRandomNum(){
srand(pow(time(0), 4)); // executes so fast that the time that passes is less than 1 seconds. So 0^4 = 0. This is the same as saying srand(0).
return rand() % 100 + 1; // always returns 84
}
int myNumAttempt1(){
int num_1 = rand(); // from kindaRandomNum
srand(time(0));
int num_2 = rand(); // from lilBetterRandomNum
return ((int)(pow(num_1 + num_2, 7)) % 100 + 1); // made this algorithm up. Doesn't really work. Can you guess why?
}
int myNumAttempt2(){
vector<int> nums(100);
for (int i = 0; i < 100; i++){ // generate 100 kindaRandomNums
int num = rand() % 100 + 1;
nums.at(i) = num;
}
int randIndex = (rand() * time(0)) % 100; // multiply rand and current time, then constrain possible numbers to 0 - 99.
return nums.at(randIndex); // why do you think this algorithm works/doesn't work?
}
int yourRandomNum(){
/* Try to create a random number generator like I did in myNumAttempt1() and myNumAttempt2()
Explain your logic, where you succeeded, and where your algorithm went wrong
Do you think it's possible to generate truly random numbers?
*/
return 0;
}
int main(){
int howMany = 7;
cout << "notSoRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << notSoRandomNum() << "\t";
} cout << endl;
cout << "stillNotSoRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << stillNotSoRandomNum() << "\t";
} cout << endl;
cout << "kindaRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << kindaRandomNum() << "\t";
} cout << endl;
cout << "lilBetterRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << lilBetterRandomNum() << "\t";
} cout << endl;
cout << "notBetterRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << notBetterRandomNum() << "\t";
} cout << endl;
cout << "myNumAttempt1(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << myNumAttempt1() << "\t";
} cout << endl;
cout << "myNumAttempt2(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << myNumAttempt2() << "\t";
} cout << endl;
cout << "yourRandomNum(): " << "\t";
for(int i = 1; i <= howMany; i++){
cout << yourRandomNum() << "\t";
} cout << endl;
return 0;
/* SAMPLE OUTPUTS
notSoRandomNum(): 84 84 84 84 84 84 84
stillNotSoRandomNum(): 84 84 84 84 84 84 84
kindaRandomNum(): 87 78 16 94 36 87 93
lilBetterRandomNum(): 11 11 11 11 11 11 11
notBetterRandomNum(): 84 84 84 84 84 84 84
myNumAttempt1(): -47 -47 -47 -47 -47 -47 -47
myNumAttempt2(): 11 98 37 43 66 62 78
yourRandomNum(): 0 0 0 0 0 0 0
notSoRandomNum(): 84 84 84 84 84 84 84
stillNotSoRandomNum(): 84 84 84 84 84 84 84
kindaRandomNum(): 87 78 16 94 36 87 93
lilBetterRandomNum(): 54 54 54 54 54 54 54
notBetterRandomNum(): 84 84 84 84 84 84 84
myNumAttempt1(): -47 -47 -47 -47 -47 -47 -47
myNumAttempt2(): 39 62 21 26 32 47 41
yourRandomNum(): 0 0 0 0 0 0 0
*/
}
Pass By Reference
#include <iostream>
using namespace std;
// CALL BY VALUE is the default way of passing parameters
// in C/C++: the parameter is a COPY of the original, so
// the function can't change the original.
int changeByValue(int x, int amount);
// CALL BY REFERENCE is indicated by the (&) after the type
// of the parameter. It means the parameter is initialized
// as a reference (aka a pointer) to the original value,
// so it can change the original.
int changeByRef(int& x, int amount);
int main(){
int x = 10;
changeByValue(x, 23);
cout << "x = " << x;
changeByRef(x, 23);
cout << "x = " << x;
return 0;
}
int changeByValue(int x, int amount) {
x = x + amount;
return x;
}
int changeByRef(int& x, int amount) {
x = x + amount;
return x;
}
Structs
#include <iostream>
#include <string>
using namespace std;
struct Employee {
int id;
string firstName;
string lastName;
int age;
double hourlyWage;
string jobTitle;
string jobDescription;
};
void printEmployeeInfo(Employee e);
int main() {
Employee me;
me.firstName = "Rebecca";
me.lastName = "Ramnauth";
me.jobTitle = "Professor of Computer Science";
me.jobDescription = "Sleep. Eat. Code.";
me.id = 10019823;
me.age = 37;
me.hourlyWage = rand() % 100 + 11.50;
Employee sh;
sh.firstName = "Sherlock";
sh.lastName = "Holmes";
sh.jobTitle = "Consulting Detective";
sh.jobDescription = "You know my methods, Watson.";
sh.id = 23987012;
sh.age = 43;
sh.hourlyWage = 0;
printEmployeeInfo(me);
printEmployeeInfo(sh);
return 0;
}
void printEmployeeInfo(Employee e) {
cout << "Employee's ID: " << e.id << endl;
cout << "Employee's Name: " << e.firstName << " " << e.lastName << endl;
cout << "Employee's Age: " << e.age << endl;
cout << "Employee's Wage: " << "$" << e.hourlyWage << endl;
cout << "Employee's Annual Salary: " << "$" << e.hourlyWage * 40 * 52 << endl;
cout << endl;
}