C / C++ / MFC

name = new char[length + 1];            //dyanamic allocation

strcpy(name, a.name);
strcpy(name, b.name);

name = new char[length + 2];            //dyanamic allocation
strcpy(name, a.name);     // copy the first name
strcat(name, " ");        // append a space character after the first name
strcat(name, b.name);     // append the second name

void String :: join(String &a, String &b){
    length = a.length + b.length ;
    delete name;
    name = new char[length + 1];            //dyanamic allocation

    strcpy(name, a.name);
    // This will overwrite name with b.name
    //strcpy(name, b.name);
    // You have to append b.name instead using strcat()
    strcat(name, b.name);
    //  or by copying to the current end
    //strcpy(name + a.length, b.name);
};

cannot convert string literal to (char *)

String(const char *s)
{
    length = strlen(s);
    name = new char[length + 1] ;
    strcpy(name, s);
}

#include <iostream>
#include <cstring>

using namespace std;

class String{
    char *name;
    int length;

public:
    String(){                                               //default constructor
        length = 0;
        name = new char[length + 1];
    }
    String(const char *s)                                         //parameterised constructor
    {
        length = strlen(s);
        name = new char[length + 1] ;

        strcpy(name, s);
    }

    void display(void){
        cout<<name<<endl;
    }
    void join(String &a, String &b);
};

void String :: join(String &a, String &b){
    length = a.length + b.length ;
    delete name;
    name = new char[length + 1];            //dyanamic allocation

    strcpy(name, a.name);
    strcat(name, b.name);
};

int main(){
    const char *first = "Joseph ";
    String name1(first), name2("louis "), name3("Lagrange "), s1, s2;

    s1.join(name1, name2);
    s2.join(s1, name3);

    name1.display();
    name2.display();
    name3.display();
    s1.display();
    s2.display();

    return 0;
}

Quote:

To avoid that message change the constructor to accept a const char* argument:

Tarun Jha wrote:

length = a.length + b.length ;

length = a.length + b.length - 1;

BOOST_ARCHIVE_DECL(const basic_serializer *)
basic_serializer_map::find(
    const boost::serialization::extended_type_info & eti
) const {
    const basic_serializer_arg bs(eti);
    map_type::const_iterator it;
    it = m_map.find(& bs);
    if(it == m_map.end()){
        BOOST_ASSERT(false);
        return 0;
    }
    return *it;
}