C++ Part 3
// ---------- C++ Tutorial 3 ----------
std::vector<int> myVec(10);
// Generates incremental values starting at 0 and places
// them in the vector provided
// begin points at the 1st index and end points at the last
// in the vector
std::iota(std::begin(myVec), std::end(myVec), 0);
// We can output the vector using a standard for loop
for(int i = 0; i < myVec.size(); ++i){
std::cout << myVec[i] << "\n";
}
// An abbreviated for loop is also available
// auto determines the data type based on the value
// y is assigned each value in the vector incrementing
// the index by 1 each time through the loop
for(auto y: myVec) std::cout << y << "\n";
// Find if a value is even / odd with modulus
int val = 8;
if((val % 2) == 0){
std::cout << val << " is Even\n";
} else {
std::cout << val << " is Odd\n";
}
// ----- PROBLEM : GENERATE VECTOR (1 - 10) AND PRINT EVENS -----
std::vector<int> myVec2(10);
std::iota(std::begin(myVec2), std::end(myVec2), 1);
// We can print just even numbers with modulus
for(auto y: myVec2){
if((y % 2) == 0)
std::cout << y << "\n";
}
// ----- END OF PROBLEM -----
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
// Needed for std::iota
#include <numeric>
// ----- FUNCTION PROTOTYPES -----
// You define the return type and data types for functions
// using a function prototype so main knows what is to be expected
// from this function
double AddNumbers(double num1, double num2);
void AssignName();
void AssignAge(int age);
int AssignAge2(int age);
// This function receives pointers
void AssignAge3(int* pAge);
// Double values in array passed
void DoubleArray(int *arr, int size);
// ----- END OF FUNCTION PROTOTYPES -----
int main() {
// ----- FUNCTIONS -----
// Code that gets above 8 to 10 lines should be broken off
// into a separate function to better organize your code
// and to promote reuse
double num1, num2;
std::cout << "Enter Num 1 : ";
// An alternative way to store a value
std::cin >> num1;
std::cout << "Enter Num 2 : ";
std::cin >> num2;
// Call the function
printf("%.1f + %.1f = %.1f\n", num1, num2, AddNumbers(num1, num2));
// Variables in a function are local to that function
// Undeclared identifier error
// std::cout << name;
// Variables values changed in a function don't
// translate globally
int age = 43;
AssignAge(age);
std::cout << "New Age " << age << "\n";
// You could change the value by passing it back
age = AssignAge2(age);
std::cout << "New Age " << age << "\n";
// A Pointer stores a address in memory
// You declare a pointer to be of the same type as the data
// type to which it points
// If you are storing the address of an int then the
// pointer is an int
// When you declare a pointer give it a null value
int* pAge = NULL;
// The reference operator returns the address for a
// variable that can be stored in a pointer
pAge = &age;
// Print the address Hexidecimal Number
std::cout << "Address : " << pAge << "\n";
// Get the value at that address with the dereference operator
std::cout << "Value at Address : " << *pAge << "\n";
// We can create a pointer to an array and cycle through
// the data with ++ and --
int intArray[] = {1,2,3,4};
int* pIntArray = intArray;
std::cout << "1st " << *pIntArray << " Address " << pIntArray << "\n";
pIntArray++;
std::cout << "2nd " << *pIntArray << " Address " << pIntArray << "\n";
pIntArray--;
std::cout << "1st"
" " << *pIntArray << " Address " << pIntArray << "\n";
// You can pass a pointer to a function and then the function
// can change that variables value globally
age = 43;
// Send the address for age to the function
AssignAge3(&age);
std::cout << "Pointer Age " << age << "\n";
// Create an array and double values
int arr[] = {1,2,3,4};
DoubleArray(arr, 4);
for(int i = 0; i < 4; ++i){
std::cout << "Array " << arr[i] << "\n";
}
return 0;
}
// ----- FUNCTIONS -----
// A function starts with the data type it will return or void
// if no value is returned
// You also list the data types for the parameters passed into
// a function and you may assign them default values
double AddNumbers(double num1 = 0, double num2 = 0){
return num1 + num2;
}
// A variable created inside a function can't be accessed
// outside of it
void AssignName(){
std::string name = "Derek";
}
void AssignAge(int age){
age = 24;
}
int AssignAge2(int age){
age = 24;
return age;
}
// Function that receives a pointer
void AssignAge3(int* pAge){
// Use dereference operator to change the value at the address
*pAge = 22;
}
// Double values in array
void DoubleArray(int *arr, int size){
for(int i = 0; i < size; ++i){
arr[i] = arr[i] * 2;
}
}
// ----- FUNCTIONS -----
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
std::vector<int> Range(int start, int max, int step);
int main() {
// ----- PROBLEM CREATE A RANGE FUNCTION -----
// Create a function that receives a starting value,
// max value and an increment amount between
// values and receive a vector in return
std::vector<int> range = Range(1, 10, 2);
// Cycle through the vector
for(auto y: range){
std::cout << y << "\n";
}
// ----- END PROBLEM CREATE A RANGE FUNCTION -----
// ----- PROBLEM CALCULATE COMPOUNDING INTEREST -----
double investment = 0.0;
double interestRate = 0.0;
std::cout << "How much to invest : ";
std::cin >> investment;
std::cout << "Interest Rate : ";
std::cin >> interestRate;
// Convert to a percent
interestRate *= .01;
for(auto y: Range(1,10,1)){
investment = investment + (investment * interestRate);
}
std::cout << "Value after 10 years : " << investment <<
"\n";
// ----- END PROBLEM CALCULATE COMPOUNDING INTEREST -----
return 0;
}
std::vector<int> Range(int start, int max, int step){
// Every while statement needs an index to start with
int i = start;
// Will hold returning vector
std::vector<int> range;
// Make sure we don't go past max value
while(i <= max){
// Add value to the vector
range.push_back(i);
// Increment the required amount
i += step;
}
return range;
}
// ---------- End of C++ Tutorial 3 ----------