When i in class constructor "Cow" want to copy char string into variable char array name program was crashed. I dont understand whats problem. strcpy need char* dist and const char* Source. I given that, but its not working.What i do wrong?
Cow::~Cow() {
delete [] hobby;
}
Cow::Cow(const char* nm, const char* ho, double wt) {
if (strlen(nm) < 20)
strcpy(name, nm);
else strcpy(name, "FailLenghtName");
hobby = new char[strlen(ho)+1];
strcpy(hobby, ho);
weight = wt;
}
class Cow {
char name[20];
char* hobby;
double weight;
public:
Cow(const char* nm, const char* ho, double wt);
~Cow();
};
int main() {
Cow Liza("Liza","Meat",120);
}
I try use any func like sprintf, but result is same
Nothing is technically wrong with the code as presented (except the missing headers and using namespace std, as Alan correctly observed).
The cast should not change anything; you are right that a string literal is an array of const char and is "adjusted" when it is passed as a parameter to a pointer to const char, which is what your constructor expects.
The constructor and destructor also seem to be correct, even though it would be better to not use literal numbers but a constant (or sizeof name! But there is always a possibility that you'll change name to also be a pointer, and then you are doomed) for the maximum string length, and — as always — much better to use the standard library facilities, here std::string.
But those are issues for a code review and only indirectly concerned with correctness (because they reduce the chance to make a mistake and make it easier to spot them if they are made).
Oh, and Ahmed's comment about "the rule of 3/5" is actually very relevant here and may well be the cause for a crash as soon as your class is actually used: Copying or assigning cows will lead to a simple copy of the hobby pointer; both instances, the original and the copy, will attempt to delete the same pointer. Only the fist of the attempts will succeed, the second one will usually lead to a crash.