2. 2016.11.24 C++ String to double

• To compile:
• string case

• # include <iostream>
  # include <string>
  using namespace std;
  
  int  main()
  {
    string str = "123456";
    double dblValue = atof( const_cast<const char *>(str.c_str()) );
    cout << dblValue << endl;
      return 0;
  }
  
  // c_str()实现由string转向char * 后再强制转换
  

• char* case

• # include <iostream>
  # include <cstdlib>
  using namespace std;
   
  int  main()
  {
      char* str="2367";
      double dvalue = atof(str);
      cout << dvalue << endl;
      return 0;
  }
  

• stringstream method

• string str = "1234.567";
  double d;
   
  stringstream sstr(str);
  sstr >> d;
  cout << d << endl;