詳解C++中stoi/stol/stoll函數(shù)的用法

更新時間：2023年03月23日 09:13:56 作者：微塵8

這篇文章主要為大家詳細介紹了C++中stoi、stol、stoll函數(shù)的具體用法，文中的示例代碼講解詳細，對我們學校C++有一點的幫助，需要的可以參考一下

stoi()函數(shù)

#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：將字符串str轉(zhuǎn)成有符號 int 整數(shù)

參數(shù)：

str：字符串
pos：存儲將字符串str轉(zhuǎn)成有符號整數(shù)，處理了str中字符的個數(shù)的地址，默認為NULL
base：進制，10：十進制，8：八進制，16：十六進制，0：則自動檢測數(shù)值進制，str是 0 開頭為八進制，str是 0x 或 0X 開頭是十六進制，默認為十進制

stoi()函數(shù)指定轉(zhuǎn)換字符串為十進制用法

#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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為十六進制用法

#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，指定十六進制
    cout << "a = " << a << endl; //a = 291
 
   str = "0x123";
    a = stoi(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為八進制用法

#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，指定八進制
    cout << "a = " << a << endl; //a = 0
 
   str = "0123"; //(3 + 2*8 + 1*8*8)
    a = stoi(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 5
 
    // str = "  -a78"; 
    // a = stoi(str, &pos, 8); //數(shù)字前有字母，調(diào)用會崩掉
    // cout << "a = " << a << endl; 
    // cout << "pos = " << pos << endl; 
 
    return 0;
}

stol()函數(shù)

#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：將字符串str轉(zhuǎn)成有符號 long 整數(shù)

參數(shù)：

str：字符串
pos：存儲將字符串str轉(zhuǎn)成有符號整數(shù)，處理了str中字符的個數(shù)的地址，默認為NULL
base：進制，10：十進制，8：八進制，16：十六進制，0：則自動檢測數(shù)值進制，str是 0 開頭為八進制，str是 0x 或 0X 開頭是十六進制，默認為十進制

stol()函數(shù)指定轉(zhuǎn)換字符串為十進制用法

#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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為十六進制用法

#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，指定十六進制
    cout << "a = " << a << endl; //a = 291
 
   str = "0x123";
    a = stol(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為八進制用法

#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，指定八進制
    cout << "a = " << a << endl; //a = 0
 
   str = "0123"; //(3 + 2*8 + 1*8*8)
    a = stol(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 5
 
    // str = "  -a78"; 
    // a = stol(str, &pos, 8); //數(shù)字前有字母，調(diào)用會崩掉
    // cout << "a = " << a << endl; 
    // cout << "pos = " << pos << endl; 
 
    return 0;
}

stoll()函數(shù)

#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：將字符串str轉(zhuǎn)成有符號 long long 整數(shù)

參數(shù)：

str：字符串
pos：存儲將字符串str轉(zhuǎn)成有符號整數(shù)，處理了str中字符的個數(shù)的地址，默認為NULL
base：進制，10：十進制，8：八進制，16：十六進制，0：則自動檢測數(shù)值進制，str是 0 開頭為八進制，str是 0x 或 0X 開頭是十六進制，默認為十進制

stoll()函數(shù)指定轉(zhuǎn)換字符串為十進制用法

#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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為十六進制用法

#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，指定十六進制
    cout << "a = " << a << endl; //a = 291
 
   str = "0x123";
    a = stoll(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    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()函數(shù)指定轉(zhuǎn)換字符串為八進制用法

#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，指定八進制
    cout << "a = " << a << endl; //a = 0
 
   str = "0123"; //(3 + 2*8 + 1*8*8)
    a = stoll(str, NULL, 0); //base = 0，自動檢測數(shù)值進制
    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); //會舍棄空白符
    cout << "a = " << a << endl; //a = -10
    cout << "pos = " << pos << endl; //pos = 5
 
    // str = "  -a78"; 
    // a = stoll(str, &pos, 8); //數(shù)字前有字母，調(diào)用會崩掉
    // cout << "a = " << a << endl; 
    // cout << "pos = " << pos << endl; 
 
    return 0;
}

注意：stoi、stol、stoll 函數(shù)是C++11標準加入的，用g++編譯器編譯需要加參數(shù)：-std=c++11

到此這篇關于詳解C++中stoi/stol/stoll函數(shù)的用法的文章就介紹到這了,更多相關C++ stoi stol stoll內(nèi)容請搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關文章希望大家以后多多支持腳本之家！

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