I am writing my own functions for malloc and free in C for an assignment. I need to take advantage of the C sbrk() wrapper function. From what I understand sbrk() increments the program’s data space by the number of bytes passed as an argument and points to the location of the program break. If … Read more
std::stoi was introduced in C++11. Make sure your compiler settings are correct and/or your compiler supports C++11.
A NULL pointer points to memory that doesn’t exist. This may be address 0x00000000 or any other implementation-defined value (as long as it can never be a real address). Dereferencing it means trying to access whatever is pointed to by the pointer. The * operator is the dereferencing operator: This is exactly the same thing as a NullReferenceException in C#, except that pointers … Read more
Allocated Array With an allocated array it’s straightforward enough to follow. Declare your array of pointers. Each element in this array points to a struct Test: Then allocate and assign the pointers to the structures however you want. Using a loop would be simple: Then declare a pointer to this array: This allows you to … Read more
Given an arbitrary type (I’ve chosen char here, but that is for sake of concrete example): You can use either of these expressions: Leading to a malloc() call such as: The last version has some benefits in that if the type of ppc changes, the expression still allocates the correct space.
The two are only partly equivalent. The difference being that: declares a two-dimensional array, which includes setting aside space for the array and ensuring that daytab references that memory. However: …only declares a pointer. So you’re trying to initialize a pointer with an array initializer, which doesn’t work as expected. There is no array; there’s no memory … Read more
Arrays can only be passed by reference, actually: This prevents you from doing things like: To be able to pass an arbitrary size array to foo, make it a template and capture the size of the array at compile time: You should seriously consider using std::vector, or if you have a compiler that supports c++11, std::array.
In this case, double means a variable of type double. double* means a pointer to a double variable. double** means a pointer to a pointer to a double variable. In the case of the function you posted, it is used to create a sort of two-dimensional array of doubles. That is, a pointer to an array of double pointers, … Read more
a is of type Album* which means that a[i] is of type Album (it is the ith element in the array of Album object pointed to by a). The left operand of -> must be a pointer; the . operator is used if it is not a pointer.
I’m learning C and I’m still not sure if I understood the difference between & and * yet. Allow me to try to explain it: I got these, but then it becomes confusing. So, both funct(*a) and funct(&a) are correct, right? What’s the difference?