string to integer

Question

I can't do this in C++

string temp = "123";
int t = atoi(temp);

why????

Answer 1

That is because atoi is expecting a raw const char* pointer. Since there is no implicit conversion from std::string to const char* you get a compiler error. Use c_str() method of std::string to get a c-style const char* for a std::string object. BTW, in C++ you can use streams to do this conversion instead of using these C-style APIs.

Answer 2

atoi(temp.c_str())