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這篇文章主要介紹“C++中的stoi/stol/stoll函數(shù)怎么使用”的相關(guān)知識,小編通過實際案例向大家展示操作過程,操作方法簡單快捷,實用性強,希望這篇“C++中的stoi/stol/stoll函數(shù)怎么使用”文章能幫助大家解決問題。
#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(rèn)為NULL
base:進(jìn)制,10:十進(jìn)制,8:八進(jìn)制,16:十六進(jìn)制,0:則自動檢測數(shù)值進(jìn)制,str是 0 開頭為八進(jìn)制,str是 0x 或 0X 開頭是十六進(jìn)制,默認(rèn)為十進(jìn)制
#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; }
#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,自動檢測數(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; }
#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,自動檢測數(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; }
#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(rèn)為NULL
base:進(jìn)制,10:十進(jìn)制,8:八進(jìn)制,16:十六進(jìn)制,0:則自動檢測數(shù)值進(jìn)制,str是 0 開頭為八進(jìn)制,str是 0x 或 0X 開頭是十六進(jìn)制,默認(rèn)為十進(jìn)制
#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; }
#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,自動檢測數(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; }
#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,自動檢測數(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; }
#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(rèn)為NULL
base:進(jìn)制,10:十進(jìn)制,8:八進(jìn)制,16:十六進(jìn)制,0:則自動檢測數(shù)值進(jìn)制,str是 0 開頭為八進(jìn)制,str是 0x 或 0X 開頭是十六進(jìn)制,默認(rèn)為十進(jìn)制
#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; }
#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,自動檢測數(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; }
#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,自動檢測數(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(biāo)準(zhǔn)加入的,用g++編譯器編譯需要加參數(shù):-std=c++11
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