407.C++ string to int

// 以下是 www.cplusplus.com 对 stoi 的说明
int stoi (const string&  str, size_t* idx = 0, int base = 10);
int stoi (const wstring& str, size_t* idx = 0, int base = 10);


Convert string to integer


Parses str interpreting its content as an integral number of the specified base,
which is returned as an int value.


If idx is not a null pointer,
the function also sets the value of idx to the position of the first character in str after the number.

// 以下是 www.cplusplus.com 对 atoi 的说明
int atoi (const char * str);


Convert string to integer


Parses the C-string str interpreting its content as an integral number,
which is returned as a value of type int.


The function first discards as many whitespace characters (as in isspace) as necessary until the first non-whitespace character is found.
Then, starting from this character, takes an optional initial plus or minus sign followed by as many base-10 digits as possible, and interprets them as a numerical value.


The string can contain additional characters after those that form the integral number, which are ignored and have no effect on the behavior of this function.


If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence exists because either str is empty or it contains only whitespace characters, no conversion is performed and zero is returned.

string s = "  10a";
cout << "s:" << stoi(s) << endl;            // 10
cout << "s:" << atoi(s.c_str()) << endl;    // 10


s = "";
// cout << "s:" << stoi(s) << endl;          core
cout << "s:" << atoi(s.c_str()) << endl;    // 0


s = " ";
// cout << "s:" << stoi(s) << endl;          core
cout << "s:" << atoi(s.c_str()) << endl;    // 0


s = "  a10";
// cout << "s:" << stoi(s) << endl;          core
cout << "s:" << atoi(s.c_str()) << endl;    // 0

try
{
    int i = boost::lexical_cast<int>("1");
}
catch (boost::bad_lexical_cast&)
{
    continue;
}