I am not able to get it what it means , "error: cannot convert ‘std::string’ to ‘const char*’ "

// Write a program to find the length of the string “refrigerator”.
#include
#include
#include
using namespace std;
main()
{
string name =“refrigerator”;
int length =strlen(name); // shows Error in this line

    cout<<"the size of refrig. is :=="<<length<<endl;
    return 0; 
}

if i use
char name[] ="refrigerator";
instead of string name =“refrigerator” it works fine , what’s the reason