CODEWITHSUNDEEP
c++stringvectorchar
user2467545
user2467545

Reputation:

How to pass a string to const char* in C++?

I am trying to split a string on . in C++ and then the first splitted string I need to pass into another method which accepts const char* key.. But everytime I do, I always get an exception -

Below is my code - 

istringstream iss(key);
std::vector<std::string> tokens;
std::string token;
while (std::getline(iss, token, '.')) {
    if (!token.empty()) {
        tokens.push_back(token);
    }
}

cout<<"First Splitted String: " <<tokens[0] << endl;
attr_map.upsert(tokens[0]); //this throws an exception
}

Below is the upsert method in AttributeMap.hh files - 

bool upsert(const char* key);

And below is the exception I always get - 

no matching function for call to AttributeMap::upsert(std::basic_string<char>&)

Is there anything I am missing?

Upvotes: 0

Views: 6889

Answers (2)

taocp
taocp

Reputation: 23624

You should use string::c_str

attr_map.upsert(tokens[0].c_str())
                        //^^^

You can check the reference for details on c_str() function.

You are getting the error because upsert function expects const char*, but you are passing std::string, type mismatch.

Upvotes: 0

Stefano Sanfilippo
Stefano Sanfilippo

Reputation: 33046

Use c_str() to get a pointer to a "null-terminated character array with data equivalent to those stored in the string" (quoting from the documentation).

attr_map.upsert(tokens[0].c_str()); //this won't throw an exception

Upvotes: 2

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