Protobuf动态和静态库

Question

I have two custom protobuf libraries. One is dynamic, other is static. Static lib has a message:

message DataType
{
    int number = 1;
    string name_1 = 2;
    string name_2 = 3;
    string name_3 = 4;
}

// The dynamic lib has a message:
message MyMessage
{
    DataType type = 1;
}

I build dynamic proto lib with linking static proto lib to it. Then I build exe application to which I link dynamic proto lib.

The problem is that when I set one of name_1, name_2 or name_3, they all have this value. I think all these strings have same buffer. If to convert dynamic lib to static, then problem disappears. Could anyone explain me what is wrong with it? Thank you.

Answer 1

If a field is not set then it should return empty string. Please check the documentation here .

If you are using version 2 you can query whether the field is set by has_name_x() .

By the way there are several ways to set a value:

• The simplest creates a copy: void set_name_x(const string& value)
• In case of C++11 you can move a string value: void set_name_x(string&& value)
• You can pass pointer: void set_allocated_name_x(string* value)
• You can get the pointer to the stored string: string* mutable_name_x()

I would advice to get familiar with protobuf and let it manage memory and use set_name_x . If it is not sufficient you can optimize your code with manual memory management.