In C , a reference is a variable that refers to another variable's address. When examining memory allocation, this raises questions about the space occupied by references compared to other data types.
Consider the code snippet:
int i = 42; int& j = i; int k = 44;
As expected, variables i and k each take up 4 bytes on the stack. However, j takes up no space in memory. This is because a reference does not itself store a value; it simply binds to the address of the variable it references, effectively acting as an alias.
So, where does a reference take up space when passed as a function argument?
When a reference is passed, the compiler assigns it a temporary location on the function's stack. This location stores the address of the variable being referenced, allowing the function to access it directly. In our example, when j is passed to a function, the function's stack holds the address of variable i.
Regarding arrays of references, the C Standard explicitly prohibits their creation:
int&[] arr = new int&[SIZE]; // compiler error! array of references is illegal
This is due to the risk of dangling references, which can point to deallocated memory. By disallowing array references, C ensures memory safety.
The above is the detailed content of How Do C References Impact Memory Allocation?. For more information, please follow other related articles on the PHP Chinese website!