The mutable storage class specifier in C++ (or use of mutable keyword in C++) auto, register, static and extern are the storage class specifiers in C. typedef is also considered as a storage class specifier in C. C++ also supports all these storage class specifiers. In addition to this C++, adds one important storage class specifier whose name is mutable.

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Wrong Code:

    const Sample sample(10,10);
    cout<<"X:\t"<<sample.x<<endl;
    sample.x += 10;
    cout<<"X:\t"<<sample.x<<endl;