Evaluate a string with a switch in C++ [duplicate]
You can map the strings to enum values, then switch on the enum: Resolving the enum can be implemented as a series of if checks: Or a map lookup:
C++
What is the difference between const int*, const int * const, and int const *?
Read it backwards (as driven by Clockwise/Spiral Rule): int* – pointer to int int const * – pointer to const int int * const – const pointer to int int const * const – const pointer to const int Now the first const can be on either side of the type so: const int * == int const * const int * const == int const … Read more
const int = int const?
They are both valid code and they are both equivalent. For a pointer type though they are both valid code but not equivalent. Declares 2 ints which are constant: Declares a pointer whose data cannot be changed through the pointer: Declares a pointer who cannot be changed to point to something else:
How to concatenate two strings in C++?
First of all, don’t use char* or char[N]. Use std::string, then everything else becomes so easy! Examples, Easy, isn’t it? Now if you need char const * for some reason, such as when you want to pass to some function, then you can do this: assuming this function is declared as: Explore std::string yourself starting from here: Documentation of std::string Hope that helps.
Segmentation fault error 11 C++
So I’m getting a segmentation fault error in the beginning of the code. I’ve tried running some tests at the different points and the error seems to be when i allocate memory for the array. Ive just started learning about heap and stack memory so I’m not really sure if I’m doing something wrong there. … Read more
What does int & mean
A C++ question, I know foo will return a pointer to int type how about what does it return? Thank a lot!
How to use the PI constant in C++
On some (especially older) platforms (see the comments below) you might need to and then include the necessary header file: and the value of pi can be accessed via: In my math.h (2014) it is defined as: but check your math.h for more. An extract from the “old” math.h (in 2009): However: on newer platforms (at least on my 64 bit … Read more
C++ table alignment – cout and iomanip
I have a small alignment issue in my program. In the output I get, the names of the months are not right justified. What seems to be the problem?
‘cout’ was not declared in this scope
Put the following code before int main(): And you will be able to use cout. For example: Now take a moment and read up on what cout is and what is going on here: http://www.cplusplus.com/reference/iostream/cout/ Further, while its quick to do and it works, this is not exactly a good advice to simply add using namespace std; at the top … Read more
streambuf::xsgetn and state flags
This is what I found on libstdc++: When the characters extracted are less than the number of characters requested, this function calls uflow() to obtain more characters. If that function returns Traits::eof() then it will simply return whether or not 0 characters were extracted. The result of the function call is picked up by the higher-level stream operations that … Read more