RAII

RAII is an acronym for Resource Acquistion is Initialization. A common, and valid, complaint about C++ is that it requires you to allocate and deallocate memory. If you get those dance steps wrong your program can spectacularly fail.

Some very smart people have come up with ways to free users from manually keeping track of memory. C++ makes it possible to define new types that behave like built-in types. You don’t have to think about allocating an int and deallocating it when done using it. RAII lets you think hard once and use the new type just like an int.

The simplest example of a string class is:

class string {
    char* s;
    int n;
public:
    // constructor
    string(char* _s, int _n)
    {
        n = _n;
        s = new char[n]; // allocate n characters
        for (int i = 0; i < n; ++i) {
            s[i] = _s[i];
        }
        
    }
    // destructor
    ~string()
    {
        delete [] s; // delete n characters
    }
}

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