Pointers is a concept that for many can be confusing at first, in particular when it comes to copying pointer values around and still referencing the same memory block. I’ve found that the best analogy is to consider the pointer as a piece of paper with a house address on it, and the memory block … Read more
It’s said that arrays “decay” into pointers. A C++ array declared as int numbers [5] cannot be re-pointed, i.e. you can’t say numbers = 0x5a5aff23. More importantly the term decay signifies loss of type and dimension; numbers decay into int* by losing the dimension information (count 5) and the type is not int [5] any … Read more
tl;dr: Methods using receiver pointers are common; the rule of thumb for receivers is, “If in doubt, use a pointer.” Slices, maps, channels, strings, function values, and interface values are implemented with pointers internally, and a pointer to them is often redundant. Elsewhere, use pointers for big structs or structs you’ll have to change, and … Read more
The C standard specifies the lower limit: 5.2.4.1 Translation limits 276 The implementation shall be able to translate and execute at least one program that contains at least one instance of every one of the following limits: […] 279 — 12 pointer, array, and function declarators (in any combinations) modifying an arithmetic, structure, union, or … Read more
When you call malloc(), you specify the amount of memory to allocate. The amount of memory actually used is slightly more than this, and includes extra information that records (at least) how big the block is. You can’t (reliably) access that other information – and nor should you :-). When you call free(), it simply … Read more
int* arr[8]; // An array of int pointers. int (*arr)[8]; // A pointer to an array of integers The third one is same as the first. The general rule is operator precedence. It can get even much more complex as function pointers come into the picture.
Arrays on the type level An array type is denoted as T[n] where T is the element type and n is a positive size, the number of elements in the array. The array type is a product type of the element type and the size. If one or both of those ingredients differ, you get … Read more
typedef is a language construct that associates a name to a type. You use it the same way you would use the original type, for instance typedef int myinteger; typedef char *mystring; typedef void (*myfunc)(); using them like myinteger i; // is equivalent to int i; mystring s; // is the same as char *s; … Read more
How is it a keyword and an instance of a type? This isn’t surprising. Both true and false are keywords and as literals they have a type ( bool ). nullptr is a pointer literal of type std::nullptr_t, and it’s a prvalue (you cannot take the address of it using &). 4.10 about pointer conversion … Read more
Reviewing the basic terminology It’s usually good enough – unless you’re programming assembly – to envisage a pointer containing a numeric memory address, with 1 referring to the second byte in the process’s memory, 2 the third, 3 the fourth and so on…. What happened to 0 and the first byte? Well, we’ll get to … Read more