詳解C++中stoi/stol/stoll函數(shù)的用法
更新時(shí)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(xì)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(xì)，對(duì)我們學(xué)校C++有一點(diǎn)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(hào) int 整數(shù)
參數(shù)：
- str：字符串
- pos：存儲(chǔ)將字符串str轉(zhuǎn)成有符號(hào)整數(shù)，處理了str中字符的個(gè)數(shù)的地址，默認(rèn)為NULL
- base：進(jìn)制，10：十進(jìn)制，8：八進(jìn)制，16：十六進(jìn)制，0：則自動(dòng)檢測(cè)數(shù)值進(jìn)制，str是 0 開(kāi)頭為八進(jìn)制，str是 0x 或 0X 開(kāi)頭是十六進(jìn)制，默認(rèn)為十進(jìn)制
stoi()函數(shù)指定轉(zhuǎn)換字符串為十進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 291
str = "0x123";
a = stoi(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 0
str = "0123"; //(3 + 2*8 + 1*8*8)
a = stoi(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(huì)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(hào) long 整數(shù)
參數(shù)：
- str：字符串
- pos：存儲(chǔ)將字符串str轉(zhuǎn)成有符號(hào)整數(shù)，處理了str中字符的個(gè)數(shù)的地址，默認(rèn)為NULL
- base：進(jìn)制，10：十進(jìn)制，8：八進(jìn)制，16：十六進(jìn)制，0：則自動(dòng)檢測(cè)數(shù)值進(jìn)制，str是 0 開(kāi)頭為八進(jìn)制，str是 0x 或 0X 開(kāi)頭是十六進(jìn)制，默認(rèn)為十進(jìn)制
stol()函數(shù)指定轉(zhuǎn)換字符串為十進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 291
str = "0x123";
a = stol(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 0
str = "0123"; //(3 + 2*8 + 1*8*8)
a = stol(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(huì)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(hào) long long 整數(shù)
參數(shù)：
- str：字符串
- pos：存儲(chǔ)將字符串str轉(zhuǎn)成有符號(hào)整數(shù)，處理了str中字符的個(gè)數(shù)的地址，默認(rèn)為NULL
- base：進(jìn)制，10：十進(jìn)制，8：八進(jìn)制，16：十六進(jìn)制，0：則自動(dòng)檢測(cè)數(shù)值進(jìn)制，str是 0 開(kāi)頭為八進(jìn)制，str是 0x 或 0X 開(kāi)頭是十六進(jìn)制，默認(rèn)為十進(jìn)制
stoll()函數(shù)指定轉(zhuǎn)換字符串為十進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 291
str = "0x123";
a = stoll(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(jìn)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(jìn)制
cout << "a = " << a << endl; //a = 0
str = "0123"; //(3 + 2*8 + 1*8*8)
a = stoll(str, NULL, 0); //base = 0，自動(dòng)檢測(cè)數(shù)值進(jìn)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(huì)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(huì)崩掉
// cout << "a = " << a << endl;
// cout << "pos = " << pos << endl;
return 0;
}注意：stoi、stol、stoll 函數(shù)是C++11標(biāo)準(zhǔn)加入的，用g++編譯器編譯需要加參數(shù)：-std=c++11
到此這篇關(guān)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(guān)C++ stoi stol stoll內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！
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