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cfunctionconstantsconst-correctness

Adding /*const*/ instead of const qualifier to char * param in function prototype

I am facing a function which takes a pointer to a char array but it performs only read operations on the mem the char * points to.

I could add const to the prototype directly before the char * parameter, but this would break the rest of the non const-correct code. I decided to add a comment /*const*/ instead to indicate that the function performs only read operations.

However, this confuses my colleagues and I wonder if adding the comments is a common approach and the criticism is unjustified.

Example:

int func(const char *readat);

versus

int func(/*const*/ char *readat);
Solution

  • Adding const to the function parameter won't break any calling code. It is allowed to assign a non-const object to a const object.

    So this is allowed:

    char c;
char *p = &c;
const char *cp = p;

    But this is not:

    char c;
const char *cp = &c;
char *p = cp;