How to Serialize a C Class Containing an std::string?

Serializing a Class with an std::string

Serializing a class that contains an std::string presents challenges due to the string's pointer-based nature. The standard technique of casting the class to a char* and writing it to a file won't work, as it does for primitive data types.

Custom Serialization Functions

A standard workaround involves creating custom serialization and deserialization functions for the class. These functions handle the reading and writing of the class data in a controlled manner.

Example Functions

For a class containing an std::string named "name", the serialization and deserialization functions could be implemented as follows:

std::ostream& MyClass::serialize(std::ostream& out) const {
    out << height;
    out << ',' // number separator
    out << width;
    out << ',' // number separator
    out << name.size(); // serialize size of string
    out << ',' // number separator
    out << name; // serialize characters of string
    return out;
}

std::istream&amp; MyClass::deserialize(std::istream&amp; in) {
    if (in) {
        int len = 0;
        char comma;
        in >> height;
        in >> comma; // read in the separator
        in >> width;
        in >> comma; // read in the separator
        in >> len; // deserialize size of string
        in >> comma; // read in the separator
        if (in &amp;&amp; len) {
            std::vector<char> tmp(len);
            in.read(tmp.data(), len); // deserialize characters of string
            name.assign(tmp.data(), len);
        }
    }
    return in;
}

Overloading Stream Operators

For easier use, you can overload the stream operators for your class:

std::ostream &amp;operator<<(std::ostream&amp; out, const MyClass &amp;obj) {
    obj.serialize(out);
    return out;
}

std::istream &amp;operator>>(std::istream&amp; in, MyClass &amp;obj) {
    obj.deserialize(in);
    return in;
}

With these functions and overloads, you can now serialize and deserialize a class containing an std::string by simply using the stream operators.

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