Question

I have written a function that parses a url and splits it into it’s components. To store the components of the URL, I pass a pointer (to the function) to the following structure called urlinfo:

typedef struct urlstruct {
    char** protocol;
    char** address;
    char** port;
    char** page;
} urlstruct;

The reason for it containing double pointers is because I don’t know how long each components of the URL will be. Inside the function, I work out the size needed to store each component and attempt to assign the memory to the components of the urlstruct using the following line:

*(urlinfo->protocol) = (char*)malloc(i * sizeof(char));

where (i * sizeof(char)) is the size required. This line causes an access violation. Does anyone know how to correctly allocate the memory?

Thanks in advance 🙂

Answer 1

Assuming you’re really using C++, you should instead just have:

struct urlstruct {
    std::string protocol;
    std::string address;
    std::string port;
    std::string page;
};

Then filling it becomes easy:

url.protocol = "http://";

And you don’t have to worry about anything else.

But, if your tag is wrong and you really need cstrings for some reason:

typedef struct {
    char* protocol;
    char* address;
    char* port;
    char* page;
} urlstruct;

You only need single pointers. You can then allocate memory for them in very close to the same way you already are:

char* proto = "http://" //Assuming you get this from somewhere
int len = strlen(proto) + 1;
urlstruct url;
url.protocol = malloc(len * sizeof(char));