How do I erase an element from std::vector<> by index?
To delete a single element, you could do: Or, to delete more than one element at once:
c++
How to read a file line by line or a whole text file at once?
ou can use std::getline : Also note that it’s better you just construct the file stream with the file names in it’s constructor rather than explicitly opening (same goes for closing, just let the destructor do the work). Further documentation about std::string::getline() can be read at CPP Reference. Probably the easiest way to read a whole text file is just … Read more
What does the explicit keyword mean?
The compiler is allowed to make one implicit conversion to resolve the parameters to a function. What this means is that the compiler can use constructors callable with a single parameter to convert from one type to another in order to get the right type for a parameter. Here’s an example class with a constructor that can … Read more
C++ for each, pulling from vector elements
For next examples assumed that you use C++11. Example with ranged-based for loops: You should use const auto &attack depending on the behavior of makeDamage(). You can use std::for_each from standard library + lambdas: If you are uncomfortable using std::for_each, you can loop over m_attack using iterators: Use m_attack.cbegin() and m_attack.cend() to get const iterators.
What is the difference between “long”, “long long”, “long int”, and “long long int” in C++?
long and long int are identical. So are long long and long long int. In both cases, the int is optional. As to the difference between the two sets, the C++ standard mandates minimum ranges for each, and that long long is at least as wide as long. The controlling parts of the standard (C++11, … Read more
c++ “Incomplete type not allowed” error accessing class reference information (Circular dependency with forward declaration)
If you will place your definitions in this order then the code will be compiled The definition of function doSomething requires the complete definition of class Ball because it access its data member. In your code example module Player.cpp has no access to the definition of class Ball so the compiler issues an error.
Parse (split) a string in C++ using string delimiter (standard C++)
You can use the std::string::find() function to find the position of your string delimiter, then use std::string::substr() to get a token. Example: The find(const string& str, size_t pos = 0) function returns the position of the first occurrence of str in the string, or npos if the string is not found. The substr(size_t pos = 0, size_t n = npos) function returns a substring of the object, … Read more
Expression must be a modifiable lvalue
The assignment operator has lower precedence than &&, so your condition is equivalent to: But the left-hand side of this is an rvalue, namely the boolean resulting from the evaluation of the subexpression match == 0 && k, so you cannot assign to it. By contrast, comparison has higher precedence, so match == 0 && k == m is … Read more
Differences between C++ string == and compare()?
This is what the standard has to say about operator== 21.4.8.2 operator== Returns: lhs.compare(rhs) == 0. Seems like there isn’t much of a difference!
What does ‘&’ do in a C++ declaration?
The “&” denotes a reference instead of a pointer to an object (In your case a constant reference). The advantage of having a function such as over is that in the former case you are guaranteed that myname is non-null, since C++ does not allow NULL references. Since you are passing by reference, the object … Read more