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详解C++中stoi/stol/stoll函数的用法

 更新时间：2023年03月23日 09:13:56   作者：微尘8  
这篇文章主要为大家详细介绍了C++中stoi、stol、stoll函数的具体用法，文中的示例代码讲解详细，对我们学校C++有一点的帮助，需要的可以参考一下

stoi()函数

#include <string>
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 <iostream>
#include <string>
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 = -1235
 
    str = "1235";
    a = stoi(str);
    cout << "a = " << a << endl; //a = 1235
 
    str = "  -12  35"; 
    a = stoi(str, &pos); //会舍弃空白符
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -12ab35";
    a = stoi(str, &pos);
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stoi(str);
    cout << "a = " << a << endl; //a = 123
 
    str = "0x123";
    a = stoi(str);
    cout << "a = " << a << endl; //a = 0
 
    return 0;
}

stoi()函数指定转换字符串为十六进制用法

#include <iostream>
#include <string>
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 = 291
 
   str = "0x123";
    a = stoi(str, NULL, 0); //base = 0，自动检测数值进制
    cout << "a = " << a << endl; //a = 291
 
    str = "-12";
    a = stoi(str, &pos, 16); //-(2 + 1*16)
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stoi(str, &pos, 16); //2 + 1*16
    cout << "a = " << a << endl; //a = 18
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stoi(str, &pos, 16); //会舍弃空白符
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -ab";
    a = stoi(str, &pos, 16); //-(11 + 10*16)
    cout << "a = " << a << endl; //a = -171
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stoi(str, NULL, 16); //(3 + 2*16 + 1*16*16)
    cout << "a = " << a << endl; //a = 291
 
    return 0;
}

stoi()函数指定转换字符串为八进制用法

#include <iostream>
#include <string>
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 = 0
 
   str = "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 = 83
 
    str = "-12";
    a = stoi(str, &pos, 8); //-(2 + 1*8)
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stoi(str, &pos, 8); //2 + 1*8
    cout << "a = " << a << endl; //a = 10
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stoi(str, &pos, 8); //会舍弃空白符
    cout << "a = " << a << endl; //a = -10
    cout << "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 <string>
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 <iostream>
#include <string>
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 = -1235
 
    str = "1235";
    a = stol(str);
    cout << "a = " << a << endl; //a = 1235
 
    str = "  -12  35"; 
    a = stol(str, &pos); //会舍弃空白符
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -12ab35";
    a = stol(str, &pos);
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stol(str);
    cout << "a = " << a << endl; //a = 123
 
    str = "0x123";
    a = stol(str);
    cout << "a = " << a << endl; //a = 0
 
    return 0;
}

stol()函数指定转换字符串为十六进制用法

#include <iostream>
#include <string>
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 = 291
 
   str = "0x123";
    a = stol(str, NULL, 0); //base = 0，自动检测数值进制
    cout << "a = " << a << endl; //a = 291
 
    str = "-12";
    a = stol(str, &pos, 16); //-(2 + 1*16)
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stol(str, &pos, 16); //2 + 1*16
    cout << "a = " << a << endl; //a = 18
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stol(str, &pos, 16); //会舍弃空白符
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -ab";
    a = stol(str, &pos, 16); //-(11 + 10*16)
    cout << "a = " << a << endl; //a = -171
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stol(str, NULL, 16); //(3 + 2*16 + 1*16*16)
    cout << "a = " << a << endl; //a = 291
 
    return 0;
}

stol()函数指定转换字符串为八进制用法

#include <iostream>
#include <string>
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 = 0
 
   str = "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 = 83
 
    str = "-12";
    a = stol(str, &pos, 8); //-(2 + 1*8)
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stol(str, &pos, 8); //2 + 1*8
    cout << "a = " << a << endl; //a = 10
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stol(str, &pos, 8); //会舍弃空白符
    cout << "a = " << a << endl; //a = -10
    cout << "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 <string>
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 <iostream>
#include <string>
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 = -1235
 
    str = "1235";
    a = stoll(str);
    cout << "a = " << a << endl; //a = 1235
 
    str = "  -12  35"; 
    a = stoll(str, &pos); //会舍弃空白符
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -12ab35";
    a = stoll(str, &pos);
    cout << "a = " << a << endl; //a = -12
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stoll(str);
    cout << "a = " << a << endl; //a = 123
 
    str = "0x123";
    a = stoll(str);
    cout << "a = " << a << endl; //a = 0
 
    return 0;
}

stoll()函数指定转换字符串为十六进制用法

#include <iostream>
#include <string>
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 = 291
 
   str = "0x123";
    a = stoll(str, NULL, 0); //base = 0，自动检测数值进制
    cout << "a = " << a << endl; //a = 291
 
    str = "-12";
    a = stoll(str, &pos, 16); //-(2 + 1*16)
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stoll(str, &pos, 16); //2 + 1*16
    cout << "a = " << a << endl; //a = 18
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stoll(str, &pos, 16); //会舍弃空白符
    cout << "a = " << a << endl; //a = -18
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "  -ab";
    a = stoll(str, &pos, 16); //-(11 + 10*16)
    cout << "a = " << a << endl; //a = -171
    cout << "pos = " << pos << endl; //pos = 5
 
    str = "0123";
    a = stoll(str, NULL, 16); //(3 + 2*16 + 1*16*16)
    cout << "a = " << a << endl; //a = 291
 
    return 0;
}

stoll()函数指定转换字符串为八进制用法

#include <iostream>
#include <string>
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 = 0
 
   str = "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 = 83
 
    str = "-12";
    a = stoll(str, &pos, 8); //-(2 + 1*8)
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 3
 
    str = "12";
    a = stoll(str, &pos, 8); //2 + 1*8
    cout << "a = " << a << endl; //a = 10
    cout << "pos = " << pos << endl; //pos = 2
 
    str = "  -12  35"; 
    a = stoll(str, &pos, 8); //会舍弃空白符
    cout << "a = " << a << endl; //a = -10
    cout << "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

到此这篇关于详解C++中stoi/stol/stoll函数的用法的文章就介绍到这了,更多相关C++ stoi stol stoll内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！

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