Question

I have a header file which contains a member variable declaration of a static char array:

class ABC 
{ 
public:
static char newArray[4];
// other variables / functions
private:
void setArray(int i, char * ptr);
}

In the CPP file, I have the array initialized to NULL:

char ABC::newArray[4] = {0};

In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer:

ABC::ABC()
{ 
int i; //some int value defined at runtime
memset(newArray, 0, 4); // not sure if this is necessary
setArray(i,newArray);
} 

...

void setArray(int i, char * value)
{
    // encoding i to set value[0] ... value [3]
}

When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration.

Any ideas why this is the case.
I just want to set the char array to 4 characters and nothing further.

Thanks…

Answer 1

How are you printing it? In C++ (and C), strings are terminated with a nul. (\0). If you’re doing something like:

char arr[4] = {'u', 'h', 'o', 'h'};
std::cout << arr;

It’s going to print “uhoh” along with anything else it runs across until it gets to a \0. You might want to do something like:

for (unsigned i = 0; i < 4; ++i)
    std::cout << arr[i];

(Having a static tied to instances of a class doesn’t really make sense, by the way. Also, you can just do = {}, though it’s not needed since static variables are zero-initialized anyway. Lastly, no it doesn’t make sense to memset something then rewrite the contents anyway.)