Question: I have a C struct defined as follows:

```
struct Guest {
   int age;
   char name[20];
};

```

When I created a `Guest` variable and initialized it using the following:

```
int guest_age = 30;
char guest_name[20] = "Mike";
struct Guest mike = {guest_age, guest_name};

```

I got the error about the second parameter initialization which tells me that `guest_name` cannot be used to initialize member variable `char name[20]`.

I could do this to initialize all:

```
struct Guest mike = {guest_age, "Mike"};

```

But this is not I want. I want to initialize all fields by variables. How to do this in C?

Answer: 
`mike.name` is 20 bytes of reserved memory inside the struct. `guest_name` is a pointer to another memory location. By trying to assign `guest_name` to the struct's member you try something impossible.

If you have to copy data into the struct you have to use `memcpy` and friends. In this case you need to handle the `\0` terminator.

```
memcpy(mike.name, guest_name, 20);
mike.name[19] = 0; // ensure termination

```

If you have `\0` terminated strings you can also use `strcpy`, but since the `name`'s size is 20, I'd suggest `strncpy`.

```
strncpy(mike.name, guest_name, 19);
mike.name[19] = 0; // ensure termination

```
mike.name is a character array. You can't copy arrays by just using the = operator.

Instead, you'll need to use `strncpy` or something similar to copy the data.

```
int guest_age = 30;
char guest_name[20] = "Mike";
struct Guest mike = { guest_age };
strncpy(mike.name, guest_name, sizeof(mike.name) - 1);

```

You've tagged this question as C++, so I'd like to point out that in that case you should almost always use `std::string` in preference to `char[]`.