I have a main function that has to receive a string.
main()
{
char *c = fun();
}
char* fun()
{
char a[] = "hello";
return a;
}
The problem is that if I return string of lenght 3 or less, then everything is good. If I return string of length > 3, then I receive garbage value along with the string. Why is that ?
You return a pointer to a local variable. The variable is stack-allocated, and it is destroyed when the function exits. Using such pointer is undefined behaviour.
char* fun()
{
char a[] = "hello";
return a;
}
Array a has automatic storage duration. At the end of the function the array object a is destroyed. This means the pointer becomes invalid at the exit of the function and any use of it is undefined behavior.
You are returning an automatic variable, which is a big no-no. That it works at all is an accident of the implementation.
The variable a is local to fun(), and so goes out of scope (and out of existence) when you return. The fact that is works for any case is pure luck. You could make a static, or dynamically allocated, or fix it in ohter ways.
