stoi()函数

#include

int stoi(const std::string& str, std::size_t* pos = 0, int base = 10);

int stoi(const std::wstring& str, std::size_t* pos = 0, int base = 10);

功能：将字符串str转成有符号 int 整数
参数：
str：字符串
pos：存储将字符串str转成有符号整数，处理了str中字符的个数的地址，默认为NULL
base：进制，10：十进制，8：八进制，16：十六进制，0：则自动检测数值进制，str是 0 开头为八进制，str是 0x 或 0X 开头是十六进制，默认为十进制

stoi()函数指定转换字符串为十进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{int a;size_t pos = 0;string str;str = "-1235";a = stoi(str);cout << "a = " << a << endl; //a = -1235str = "1235";a = stoi(str);cout << "a = " << a << endl; //a = 1235str = "  -12  35"; a = stoi(str, &pos); //会舍弃空白符cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "  -12ab35";a = stoi(str, &pos);cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoi(str);cout << "a = " << a << endl; //a = 123str = "0x123";a = stoi(str);cout << "a = " << a << endl; //a = 0return 0;
}

stoi()函数指定转换字符串为十六进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{int a;size_t pos = 0;string str;str = "0x123";a = stoi(str, NULL, 16); //base = 16，指定十六进制cout << "a = " << a << endl; //a = 291str = "0x123";a = stoi(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 291str = "-12";a = stoi(str, &pos, 16); //-(2 + 1*16)cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoi(str, &pos, 16); //2 + 1*16cout << "a = " << a << endl; //a = 18cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoi(str, &pos, 16); //会舍弃空白符cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 5str = "  -ab";a = stoi(str, &pos, 16); //-(11 + 10*16)cout << "a = " << a << endl; //a = -171cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoi(str, NULL, 16); //(3 + 2*16 + 1*16*16)cout << "a = " << a << endl; //a = 291return 0;
}

stoi()函数指定转换字符串为八进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{int a;size_t pos = 0;string str;str = "0x123";a = stoi(str, NULL, 8); //base = 8，指定八进制cout << "a = " << a << endl; //a = 0str = "0123"; //(3 + 2*8 + 1*8*8)a = stoi(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 83str = "-12";a = stoi(str, &pos, 8); //-(2 + 1*8)cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoi(str, &pos, 8); //2 + 1*8cout << "a = " << a << endl; //a = 10cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoi(str, &pos, 8); //会舍弃空白符cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 5// str = "  -a78"; // a = stoi(str, &pos, 8); //数字前有字母，调用会崩掉// cout << "a = " << a << endl; // cout << "pos = " << pos << endl; return 0;
}

stol()函数

#include

long stol(const std::string& str, std::size_t* pos = 0, int base = 10);

long stol(const std::wstring& str, std::size_t* pos = 0, int base = 10);

功能：将字符串str转成有符号 long 整数
参数：
str：字符串
pos：存储将字符串str转成有符号整数，处理了str中字符的个数的地址，默认为NULL
base：进制，10：十进制，8：八进制，16：十六进制，0：则自动检测数值进制，str是 0 开头为八进制，str是 0x 或 0X 开头是十六进制，默认为十进制

stol()函数指定转换字符串为十进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long a;size_t pos = 0;string str;str = "-1235";a = stol(str);cout << "a = " << a << endl; //a = -1235str = "1235";a = stol(str);cout << "a = " << a << endl; //a = 1235str = "  -12  35"; a = stol(str, &pos); //会舍弃空白符cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "  -12ab35";a = stol(str, &pos);cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stol(str);cout << "a = " << a << endl; //a = 123str = "0x123";a = stol(str);cout << "a = " << a << endl; //a = 0return 0;
}

stol()函数指定转换字符串为十六进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long a;size_t pos = 0;string str;str = "0x123";a = stol(str, NULL, 16); //base = 16，指定十六进制cout << "a = " << a << endl; //a = 291str = "0x123";a = stol(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 291str = "-12";a = stol(str, &pos, 16); //-(2 + 1*16)cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 3str = "12";a = stol(str, &pos, 16); //2 + 1*16cout << "a = " << a << endl; //a = 18cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stol(str, &pos, 16); //会舍弃空白符cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 5str = "  -ab";a = stol(str, &pos, 16); //-(11 + 10*16)cout << "a = " << a << endl; //a = -171cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stol(str, NULL, 16); //(3 + 2*16 + 1*16*16)cout << "a = " << a << endl; //a = 291return 0;
}

stol()函数指定转换字符串为八进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long a;size_t pos = 0;string str;str = "0x123";a = stol(str, NULL, 8); //base = 8，指定八进制cout << "a = " << a << endl; //a = 0str = "0123"; //(3 + 2*8 + 1*8*8)a = stol(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 83str = "-12";a = stol(str, &pos, 8); //-(2 + 1*8)cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 3str = "12";a = stol(str, &pos, 8); //2 + 1*8cout << "a = " << a << endl; //a = 10cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stol(str, &pos, 8); //会舍弃空白符cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 5// str = "  -a78"; // a = stol(str, &pos, 8); //数字前有字母，调用会崩掉// cout << "a = " << a << endl; // cout << "pos = " << pos << endl; return 0;
}

stoll()函数

#include

long long stoll(const std::string& str, std::size_t* pos = 0, int base = 10);

long long stoll(const std::wstring& str, std::size_t* pos = 0, int base = 10);

功能：将字符串str转成有符号 long long 整数
参数：
str：字符串
pos：存储将字符串str转成有符号整数，处理了str中字符的个数的地址，默认为NULL
base：进制，10：十进制，8：八进制，16：十六进制，0：则自动检测数值进制，str是 0 开头为八进制，str是 0x 或 0X 开头是十六进制，默认为十进制

stoll()函数指定转换字符串为十进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long long a;size_t pos = 0;string str;str = "-1235";a = stoll(str);cout << "a = " << a << endl; //a = -1235str = "1235";a = stoll(str);cout << "a = " << a << endl; //a = 1235str = "  -12  35"; a = stoll(str, &pos); //会舍弃空白符cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "  -12ab35";a = stoll(str, &pos);cout << "a = " << a << endl; //a = -12cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoll(str);cout << "a = " << a << endl; //a = 123str = "0x123";a = stoll(str);cout << "a = " << a << endl; //a = 0return 0;
}

stoll()函数指定转换字符串为十六进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long long a;size_t pos = 0;string str;str = "0x123";a = stoll(str, NULL, 16); //base = 16，指定十六进制cout << "a = " << a << endl; //a = 291str = "0x123";a = stoll(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 291str = "-12";a = stoll(str, &pos, 16); //-(2 + 1*16)cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoll(str, &pos, 16); //2 + 1*16cout << "a = " << a << endl; //a = 18cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoll(str, &pos, 16); //会舍弃空白符cout << "a = " << a << endl; //a = -18cout << "pos = " << pos << endl; //pos = 5str = "  -ab";a = stoll(str, &pos, 16); //-(11 + 10*16)cout << "a = " << a << endl; //a = -171cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoll(str, NULL, 16); //(3 + 2*16 + 1*16*16)cout << "a = " << a << endl; //a = 291return 0;
}

stoll()函数指定转换字符串为八进制用法

#include 
#include 
using namespace std;int main(int argc, char *argv[])
{long long a;size_t pos = 0;string str;str = "0x123";a = stoll(str, NULL, 8); //base = 8，指定八进制cout << "a = " << a << endl; //a = 0str = "0123"; //(3 + 2*8 + 1*8*8)a = stoll(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 83str = "-12";a = stoll(str, &pos, 8); //-(2 + 1*8)cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoll(str, &pos, 8); //2 + 1*8cout << "a = " << a << endl; //a = 10cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoll(str, &pos, 8); //会舍弃空白符cout << "a = " << a << endl; //a = -10cout << "pos = " << pos << endl; //pos = 5// str = "  -a78"; // a = stoll(str, &pos, 8); //数字前有字母，调用会崩掉// cout << "a = " << a << endl; // cout << "pos = " << pos << endl; return 0;
}

注意：stoi、stol、stoll 函数是C++11标准加入的，用g++编译器编译需要加参数：-std=c++11