the equality operator is not matched in the code

Question

for the following code I am getting error

receive_cmd.cpp:12:40: error: no match for 'operator==' in 'tmp_cmd == gold_rom[tmp_cmd.cmd::cmd_id]'

void tb::receive_cmds(){
 cmd tmp_cmd;
 cmd gold_rom[128];
 wait(1, SC_NS);
 cmd_error = false;
 while(true){
 tmp_cmd = tb_cmd_in->read();
 if (tmp_cmd == gold_rom[tmp_cmd.cmd_id]) {
 cout << sc_time_stamp() << " " << name();
 cout << ": received correct result for: " << tmp_cmd << endl;
 }
 else {
 cmd_error++;
 cout << sc_time_stamp() << " " << name();
 cout << ": ERROR command = "<< tmp_cmd
 << ", should be: "
 << gold_rom[tmp_cmd.cmd_id];
 }
 num_cmds --;
 cmd_received.notify();
 }
}

The `==` needs to be overloaded unlike java which compares memory location. — Jake Freeman, Jan 05 '18 at 15:10

iBug · Answer 1 · 2018-01-05T15:57:19.193

1

You need to explicitly provide an overload for bool cmd::operator==(const cmd &).

This is C++, not Java. There's no automatic comparison operator generated for you. You should write one for every comparison that involves user-defined types that you want to use. Here's a simple example:

class A {
    public:
    int a;
    A(int _a) : a(_a) {}
    bool operator == (const A & ref) const;
};


bool A::operator == (const A & ref) const {
    return this->a == ref.a;
}

A x(5), y(5), z(7);
bool b1 = (x == y); // b1 is true
bool b2 = (x == z); // b2 is false

edited Jan 05 '18 at 15:57

answered Jan 05 '18 at 15:25

iBug

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For the record, Java doesn't create automatic comparison operators, it just twists the meaning of `==` to automatically compare pointers to objects. Java also doesn't automatically create a correct `equals` method. You have to do it all yourself, or at least with the help of the IDE. So that situation is very much comparable (no pun intended) to C++. – Christian Hackl Jan 05 '18 at 16:20

score 1 · Answer 2 · answered Jan 05 '18 at 15:29

You are using an object of type cmd, and you are doing a == comparison on it.
You didn’t show the class implementation but it seems like this class does not have a definition for the equality comparison operator.
Therefore, the compiler is telling you that it doesn’t know how to do this equal comparison

the equality operator is not matched in the code

2 Answers2