Convert string type to int type in C + +

The write program needs to convert the string to int, so I explored it.

　　Method One: Atoi function

　　The Atoi function converts a string to an integer, noting that the Stdlib library is required. So I tried it on a bit:

　　

1#include <iostream>2#include <string.h>3#include <stdlib.h>4 using namespacestd;5 intMain ()6 {7     stringA=" One", b=" A";8Cout<<atoi (a) +atoi (b) <<Endl;9     return 0;Ten  One}

However, the error was found:

　　

Obviously, what Atoi needs is a const char* type, and I'm going to add a function string.c_str () to the above string type. String.c_str is a function in the Borland encapsulated string class that returns the first character address of the current string.

The return value of the C_STR function is const char*, so we add the C_str () function:

　

#include <iostream><string.h><stdlib.h>usingnamespace  std; int Main () {    string a="One", b=" ;    cout<<atoi (A.c_str ()) +atoi (B.c_str ()) <<Endl;     return 0 ;}

And then succeed, what's wrong with the hope that you will point out.

　　

　　

Convert string type to int type in C + +