586 Answered Questions for the topic C++

C++

08/06/19

Why does the order in which libraries are linked sometimes cause errors in GCC?
Why does the order in which libraries are linked sometimes cause errors in GCC?
Follows • 1
Expert Answers •1
C++

08/05/19

What is the meaning of prepended double colon "::"?
I found this line of a code in a class which I have to modify: ::Configuration * tmpCo = m_configurationDB;//pointer to current db and I don't know what exactly means the double colon prepended... more
Follows • 1
Expert Answers •1
C++

08/04/19

Advantages of using forward?
In perfect forwarding, `std::forward` is used to convert the named rvalue references `t1` and `t2` to unnamed rvalue references. What is the purpose of doing that? How would that affect the called... more
Follows • 1
Expert Answers •1
C++

08/04/19

How to convert vector to array?
How do I convert a `std::vector<double>` to a `double array[]`?
Follows • 1
Expert Answers •1
C++

08/03/19

Difference between static and shared libraries?
What is the difference between static and shared libraries? I use Eclipse and there are several project types including Static Libraries and Shared Libraries? Does one have an advantage over the... more
Follows • 1
Expert Answers •1
C++

08/02/19

What are the barriers to understanding pointers and what can be done to overcome them?
Why are pointers such a leading factor of confusion for many new, and even old, college level students in C or C++? Are there any tools or thought processes that helped you understand how pointers... more
Follows • 1
Expert Answers •1
C++

07/31/19

What is the difference between const int*, const int * const, and int const *?
I always mess up how to use `const int*`, `const int * const`, and `int const *` correctly. Is there a set of rules defining what you can and cannot do? I want to know all the do's and all don'ts... more
Follows • 1
Expert Answers •1
C++

07/30/19

What is the difference between the dot (.) operator and -> in C++?
What is the difference between the dot (.) operator and -> in C++?
Follows • 1
Expert Answers •1
C++

07/30/19

Why does changing 0.1f to 0 slow down performance by 10x?
Why does this bit of code, const float x[16] = { 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6}; const float z[16] = {1.123,... more
Follows • 1
Expert Answers •1
C++

07/30/19

How do I execute a command and get output of command within C++ using POSIX?
I am looking for a way to get the output of a command when it is run from within a C++ program. I have looked at using the system() function, but that will just execute a command. Here's an example... more
Follows • 1
Expert Answers •1
C++

07/29/19

Pointer vs. Reference?
What would be better practice when giving a function the original variable to work with: unsigned long x = 4; void func1(unsigned long& val) { val = 5; } func1(x); or: ... more
Follows • 1
Expert Answers •1
C++

07/28/19

Initialization of a normal array with one default value?
[C++ Notes: Array Initialization](http://www.fredosaurus.com/notes-cpp/arrayptr/array-initialization.html) has a nice list over initialization of arrays. I have a int array[100] = {-1};expecting... more
Follows • 1
Expert Answers •1
C++

07/28/19

How to check that an element is in a std::set?
How do you check that an element is in a set? Is there a simpler equivalent of the following code: myset.find(x) != myset.end()
Follows • 1
Expert Answers •1
C++

07/27/19

When to use extern in C++?
I'm reading "Think in C++" and it just introduced the `extern` declaration. For example: extern int x; extern float y; I think I understand the meaning (declaration without definition), but... more
Follows • 2
Expert Answers •1
C++

07/27/19

What do single quotes do in C++ when used on multiple characters?
I'm curious about this code: cout << 'test'; // Note the single quotes. gives me an output of `1952805748`. My question: Is the output an address in memory or something?
Follows • 1
Expert Answers •1
C++

07/27/19

Why use apparently meaningless do-while and if-else statements in macros?
In many C/C++ macros I'm seeing the code of the macro wrapped in what seems like a meaningless `do while` loop. Here are examples. #define FOO(X) do { f(X); g(X); } while (0) #define FOO(X) if... more
Follows • 1
Expert Answers •1
C++

07/26/19

How to get rid of `deprecated conversion from string constant to ‘char*’` warnings in GCC?
So I'm working on an exceedingly large codebase, and recently upgraded to gcc 4.3, which now triggers this warning: > warning: deprecated conversion from string constant to ‘char*’ Obviously,... more
Follows • 1
Expert Answers •1
C++

07/25/19

unsigned int vs. size_t?
I notice that modern C and C++ code seems to use `size_t` instead of `int`/`unsigned int` pretty much everywhere - from parameters for C string functions to the STL. I am curious as to the reason... more
Follows • 2
Expert Answers •1
C++

07/23/19

When to use dynamic vs. static libraries?
When creating a class library in C++, you can choose between dynamic (`.dll`, `.so`) and static (`.lib`, `.a`) libraries. What is the difference between them and when is it appropriate to use which?
Follows • 1
Expert Answers •1
C++

07/23/19

Check if a string contains a string in C++?
I have a variable of type `std::string`. I want to check if it contains a certain `std::string`. How would I do that? Is there a function that returns true if the string is found, and false if it... more
Follows • 1
Expert Answers •1
C++

07/22/19

Differences between C++ string == and compare()?
I just read some recommendations on using std::string s = get_string(); std::string t = another_string(); if( !s.compare(t) ) { instead of if( s == t ) { I'm almost always... more
Follows • 1
Expert Answers •1
C++

07/21/19

Static constant string (class member)?
I'd like to have a private static constant for a class (in this case a shape-factory). I'd like to have something of the sort. class A { private: static const string RECTANGLE =... more
Follows • 1
Expert Answers •1
C++

07/21/19

Are == and != mutually dependent?
I'm learning about operator overloading in C++, and I see that `==` and `!=` are simply some special functions which can be customized for user-defined types. My concern is, though, why are there... more
Follows • 1
Expert Answers •1
C++

07/20/19

Struct Constructor in C++?
Can a `struct` have a constructor in C++? I have been trying to solve this problem but I am not getting the syntax.
Follows • 1
Expert Answers •1
C++

07/19/19

When should you use constexpr capability in C++11?
It seems to me that having a "function that always returns 5" is breaking or diluting the meaning of "calling a function". There must be a reason, or a need for this capability or it wouldn't be in... more
Follows • 1
Expert Answers •1

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.