I use google search on everything, but actually to my big surprise, I find searching on line is not helpful for me in C++. This is because I am barely starting to learn, all the links are from like forums where people are much more advance than me. When I read their programs, there are more terms that I don't know than I know. So the programs don't even make sense to me. I don't see and simple explanation on anything.FactChecker said:One thing that you should realize is that the documentation of C++ is so large that on-line and computerized documentation has huge advantages and might be the only practical way to do it. They can include hyperlinks, search tools, and syntax-dependent recommendations that no number of books can match.
//Assign Values to Elements in an Array
#include<iostream>
using namespace std;
constexpr int Square(int number) { return number * number;}// set constant function Square.
int main()
{
const int ARRAY_LENGTH = 5;
int myNumbers[ARRAY_LENGTH] = { 5, 10, 0, -101, 20 };
int moreNumbers[Square(ARRAY_LENGTH)];// replace the constant number for length with a constant function.
cout << "Enter index of the element to be changed: ";
int elementIndex = 0;
cin >> elementIndex;
cout << "Enter new value: ";
int newValue = 0;
cin >> newValue;
myNumbers[elementIndex] = newValue;
moreNumbers[elementIndex] = newValue;
cout << "Element" << elementIndex << "in array mynuNumbers is: " << myNumbers[elementIndex] << endl;
cout << "Element" << elementIndex << " in array moreNumbers is: " << moreNumbers[elementIndex] << endl;
cout << "The size of moreNumbers[] is: " << sizeof(moreNumbers) << endl;
return 0;
}How can I forgot that!Jarvis323 said:sizeof returns the size in bytes and there are 4 bytes per int
I even modified the array by declaring the array is characters: char morNumbers[]Jarvis323 said:sizeof returns the size in bytes and there are 4 bytes per int
Jarvis323 said:there are 4 bytes per int
I am just verify the line sizeof() if I change to character as it's 1 byte. Just playing around. I am playing around with the example given by the book by adding things and try it out. It's been fun.FactChecker said:I don't think that one byte is large enough to hold the numbers that you want to put in it. newValue is an integer and needs 4 bytes. You can always leave the array large enough for an integer and print sizeof(Array)/sizeof(int).
Jarvis323 said:there are 4 bytes per int
An int is 4 bytes (currently) whether you're compiling 32-bit or 64-bit code. That is definitely the case with Visual Studio, and is probably the case with other compilers as well. The long long (AKA long long int) type is 8 bytes, as is unsigned long long.PeterDonis said:8 bytes if you're compiling 64-bit code. (And way back in the Stone Age there was code where an int was only 2 bytes, or even 1 byte.)
That's not really syntax -- it's just the size (in bytes) of that data type. You can use the sizeof operator (it's considered an operator, like +, -, *, /, etc., rather than a function) to determine the size of any type or any variable.yungman said:I am just verify the line sizeof() if I change to character as it's 1 byte. Just playing around. I am playing around with the example given by the book by adding things and try it out. It's been fun.
Thanks for the new syntax for integer ( 4 bytes)
int List[] = {2, 5, 8, 10, 11, 31, -2, 15, 25};
int size = sizeof(List) / sizeof (int);Agreed it is very useful, but technically, sizeof is an operator, just like +, -, *, <<, ^, and so on.FactChecker said:The sizeof() function can be very useful sometimes.
That makes me feel a lot better. I was looking at the book, there's no way they can cover the whole book in one semester. It is so deceiving that the tittle of the book is "Learn C++ one hour a day", one hour a day, it will take a long time! I put like 3 to 4 hours a day for almost a week, I barely cover the first 4 chapters and starting on the 5th. It's just have a lot of new names (terms) and it's so hard to remember. I don't think the book is that good, it goes over a lot of terms in the first 4 chapters with no details, then repeat again in the later chapters. Particular Chapter 4, it actually said for detail, refer to chapter 17!Jarvis323 said:In my experience, C++ was just the language used in an object oriented programming course, and was the 3rd programming course you would take.
They skipped over the stuff in part 1 of that book (which was the subject of a previous course in C), and focus instead on classes, encapsulation, polymorphism, and inheritance (part 2). The course was project based and the book was just used for students as a reference.
A course following object oriented programming was data structures and algorithms. In that course you'd learn about some of part 3 in the book. The focus would be on the underlying algorithms and when to use them, analyze expected and worst case performance, and implement some of them and others yourself from scratch as part of different projects.
The content of parts 4 and 5 were not really covered.
No courses focused specifically on learning C++, just used basic/simple parts of C++ as a base to teach general concepts. I think that they expect people to learn the details of specific languages independently, as there are many of them and they change. Learning new languages and technologies independently is also a sort of long term survival skill in industry.
Anyway, I think your book is about 3 semesters worth of content, but they would include a lot of projects.
You are putting in an impressive level of effort. I think that you will be in very good shape by Christmas. There is a lot to get oriented on initially and it can make progress seem slow. But I think that you may be beyond that and will start to get traction quickly.yungman said:I am hoping I can finish Part 1 to 3 by Christmas.
Thanks for you complement. I am trying hard to learn. But I think I bull through the 4 chapter too fast, too many new names. I am going to spend the next day to go through them again and update my notes to make sure I have a better feel of the names. It's all the class, function, object etc. that really throws me off. Just have to keep reading and hopefully they will sink in.FactChecker said:You are putting in an impressive level of effort. I think that you will be in very good shape by Christmas. There is a lot to get oriented on initially and it can make progress seem slow. But I think that you may be beyond that and will start to get traction quickly.
Wow, this is what I need. Perfect timing while I am reviewing the first 4 chapters. I have a few questions:1) I put this in the heading of my notes and I change a little. I highlighted the key words. I want to confirm using #include<iostream>:FactChecker said:Object Oriented Programming can come from left field sometimes. I came from a background of computer discrete event simulation and OOP was exactly what I wanted. Suppose you are simulating a road intersection and want to generate a stream of cars coming and going. You want each car to control itself according to some rules and to collect its own statistics without getting it confused with all the other cars. You would make a class of vehicles and each car that you generate (instantiate) is an object in that class. The class defines how it will operate and collect data (using methods and hidden data), but the object itself does all the work and collects data internally, without getting it confused with the other cars (objects). Thousands of cars can be generated (instantiated), do their thing (using methods defined for the class), and destroyed (using the destructor method) as they enter and leave the intersection. OOP greatly simplifies simulations like that.
#include <iostream>
#include <vector>
using namespace std;
int main()
{
vector<int> dynArray(3);// define dynamic array of 3 elements
dynArray[0] = 365;
dynArray[1] = -421;
dynArray[2] = 789;
cout << " Numberof integers in array: " << dynArray.size() << endl; //display the array length
cout << "Enter another element to insert" << endl;
int newValue = 0;
cin >> newValue;
dynArray.push_back(newValue);
cout << " Numberof integers in array: " << dynArray.size() << endl;// Display the new array length
cout << " The last element of array: ";
cout << dynArray[dynArray.size() - 1] << endl; //The Nth element is dynArray(N-1)
return 0;
}In your first line, pi is initialized to 3. In the second line, pi is initialized to 3.0. This is because 22/7 == 3, due to integer division. Because pi is declared as a float in that line, the value 3 gets promoted to a float value, 3.0.yungman said:I want to confirm declaration of constant:
int pi = 22/7 = 3
float pi =22/7 = 3.1429
So if I want decimal number, I declare float?
Oh! I am still wrong! So how do I get 3.1428?Mark44 said:In your first line, pi is initialized to 3. In the second line, pi is initialized to 3.0. This is because 22/7 == 3, due to integer division. Because pi is declared as a float in that line, the value 3 gets promoted to a float value, 3.0.
No, std is a namespace: a collection of classes and other stuff. Yes, cout is an object -- a stream object.yungman said:Wow, this is what I need. Perfect timing while I am reviewing the first 4 chapters. I have a few questions:1) I put this in the heading of my notes and I change a little. I highlighted the key words. I want to confirm using #include<iostream>:
Is iostream a HEADER file where std is the CLASS and cout is OBJECT?
The .cpp file is your source code. The compiler translates it into machine code -- an object file (not objective file). Note that the meaning of object here is different from its use in object-oriented programming. The linker merges in code for whatever library functions you've used.yungman said:2) What do you call the .cpp text file that I created in VS? Is the compiler transforms the text .cpp file into machine code called OBJECTIVE file? Then the next step is to link with other files to form the complete .exe file?
Yes, main() is a function. Your program can consist of multiple functions. Note that in C, C++, you can't define a function inside of another function.yungman said:3) Do you call main() {multiple lines of codes} that is the body of the program as FUNCTION? In fact I can declare any myfunction() { multiple lines of codes} as FUNCTION within the .cpp text file.
yungman said:I am sure I have more question later.
Thanks
Declare pi so that floating point division is performed.yungman said:Oh! I am still wrong! So how do I get 3.1428?
there goes to show it's never too dumb to ask!
double pi = 22.0/7;The erase() member function of the vector class will shrink the array.yungman said:I understand the line 17 the number of elements increased by 1 using .push_back() to stuff in the new number. My question is if I don't need that many elements, is there a command to SHRINK the array back?
The << operator is overloaded, meaning that it has two different purposes.* #include <iostream> to perform cout to output streams to display using std::cout << follow by
the “asdfongfasd” for words etc. Where << operator to shift bits LEFT.
What is the meaning of overloaded? Just simple having two purposes? Why don't they call it dual purpose?Mark44 said:From your notes, Ch. 1:
The << operator is overloaded, meaning that it has two different purposes.
When it appears with cout, the meaning is to send a stream of bytes to output.
When it appears in an arithmetic express, such as count << 2, it shifts all the bits left by two places.
Several operators are overloaded in C++. These include >>, which is used for both input as well as shifting bits; * is used for multiplication and pointer dereferencing, & is used for bitwise AND and for getting the address of a variable.
There can be more than two purposes. In C++, but not C (unless it has changed in recent new standards), a function or operator can be overloaded. Here's an example showing the declarations (prototypes) of a function named fun with four overloads.yungman said:What is the meaning of overloaded? Just simple having two purposes? Why don't they call it dual purpose?
int fun(int, int);
int fun(unsigned, unsigned);
int fun(float, float);
int fun(double, double);They would have to call it n-purpose or multi-purpose because there is no limit. When you define a class, you are allowed to redefine the common operations to make sense in the context of that class. A class of vectors can redefine '+' to add vectors component-wise. A class of data can redefine '+' to put the new data into a database. etc., etc.yungman said:What is the meaning of overloaded? Just simple having two purposes? Why don't they call it dual purpose?
I don't think I learn fun(int, int) type, what is this?Mark44 said:There can be more than two purposes. In C++, but not C (unless it has changed in recent new standards), a function or operator can be overloaded. Here's an example showing the declarations (prototypes) of a function named fun with four overloads.
A possible motivation might be that each overload adds a pair of numbers of each type. This is a bit fakey, since the function's return type is int, and all overloads must share the same return type.C++:int fun(int, int); int fun(unsigned, unsigned); int fun(float, float); int fun(double, double);