stoul() 函数

#include <string>

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

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

功能：将字符串 str 转成 unsigned long 整数
参数：
str：字符串
pos：存储将字符串 str 转成 unsigned long 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

stoul() 函数指定转换字符串为十进制用法

stoul.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long a; //x86_64构架下，unsigned long 8个字节size_t pos = 0;string str;cout << "ULONG_MAX = " << ULONG_MAX << endl;str = "-1"; a = stoul(str); //数据在内存中是以补码的形式存储的，负数的补码等于反码加1/*-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111*/cout << "a = " << a << endl; // a = (最大值) +（负数）+ 1，即：((2^64) - 1) + (-1) + 1 str = "1235";a = stoul(str);cout << "a = " << a << endl; //a = 1235str = "  -12  35"; a = stoul(str, &pos); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-12) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -12ab35";a = stoul(str, &pos);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-12) + 1cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoul(str);cout << "a = " << a << endl; //a = 123str = "0x123";a = stoul(str);cout << "a = " << a << endl; //a = 0return 0;
}

stoul() 函数指定转换字符串为十六进制用法

stoul.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long a; //x86_64构架下，unsigned long 8个字节size_t pos = 0;string str;cout << "ULONG_MAX = " << ULONG_MAX << endl;/*数据在内存中是以补码的形式存储的，负数的补码等于反码加1-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111-1转成unsigned long：(最大值) +（负数）+ 1-1转成unsigned long：((2^64) - 1) + (-1) + 1*/str = "0x123"; a = stoul(str, NULL, 16); //base = 16，指定十六进制cout << "a = " << a << endl; //a = 3 + 2*16 + 1*16*16 = 291str = "0x123";a = stoul(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 291str = "  -12"; a = stoul(str, &pos, 16); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(2 + 1*16)) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -12 35";a = stoul(str, &pos, 16);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(2 + 1*16)) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -ab";a = stoul(str, NULL, 16);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(11 + 10*16)) + 1str = "0123";a = stoul(str, NULL, 16);   cout << "a = " << a << endl; //a = (3 + 2*16 + 1*16*16) = 291return 0;
}

stoul() 函数指定转换字符串为八进制用法

stoul.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long a; //x86_64构架下，unsigned long 8个字节size_t pos = 0;string str;cout << "ULONG_MAX = " << ULONG_MAX << endl;/*数据在内存中是以补码的形式存储的，负数的补码等于反码加1-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111-1转成unsigned long：(最大值) +（负数）+ 1-1转成unsigned long：((2^64) - 1) + (-1) + 1*/str = "0x123";a = stoul(str, NULL, 8); //base = 8，指定八进制cout << "a = " << a << endl; //a = 0str = "0123"; //(3 + 2*8 + 1*8*8)a = stoul(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = (3 + 2*8 + 1*8*8) = 83str = "-12";a = stoul(str, &pos, 8); //-(2 + 1*8)cout << "a = " << a << endl; //a = ((2^64) - 1) + (-10) + 1cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoul(str, &pos, 8); //2 + 1*8cout << "a = " << a << endl; //a = 10cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoul(str, &pos, 8); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-10) + 1cout << "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;
}

stoull() 函数

#include <string>

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

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

功能：将字符串 st r转成 unsigned long long 整数
参数：
str：字符串
pos：存储将字符串 str 转成 unsigned long long 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

stoull() 函数指定转换字符串为十进制用法

stoull.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long long a; //x86_64构架下，unsigned long long 8个字节size_t pos = 0;string str;cout << "ULLONG_MAX = " << ULLONG_MAX << endl;str = "-1"; a = stoull(str); //数据在内存中是以补码的形式存储的，负数的补码等于反码加1/*-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111*/cout << "a = " << a << endl; // a = (最大值) +（负数）+ 1，即：((2^64) - 1) + (-1) + 1 str = "1235";a = stoull(str);cout << "a = " << a << endl; //a = 1235str = "  -12  35"; a = stoull(str, &pos); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-12) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -12ab35";a = stoull(str, &pos);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-12) + 1cout << "pos = " << pos << endl; //pos = 5str = "0123";a = stoull(str);cout << "a = " << a << endl; //a = 123str = "0x123";a = stoull(str);cout << "a = " << a << endl; //a = 0return 0;
}

stoull() 函数指定转换字符串为十六进制用法

stoull.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long long a; //x86_64构架下，unsigned long long 8个字节size_t pos = 0;string str;cout << "ULLONG_MAX = " << ULLONG_MAX << endl;/*数据在内存中是以补码的形式存储的，负数的补码等于反码加1-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111-1转成unsigned long long：(最大值) +（负数）+ 1-1转成unsigned long long：((2^64) - 1) + (-1) + 1*/str = "0x123"; a = stoull(str, NULL, 16); //base = 16，指定十六进制cout << "a = " << a << endl; //a = 3 + 2*16 + 1*16*16 = 291str = "0x123";a = stoull(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = 291str = "  -12"; a = stoull(str, &pos, 16); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(2 + 1*16)) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -12 35";a = stoull(str, &pos, 16);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(2 + 1*16)) + 1cout << "pos = " << pos << endl; //pos = 5str = "  -ab";a = stoull(str, NULL, 16);cout << "a = " << a << endl; //a = ((2^64) - 1) + (-(11 + 10*16)) + 1str = "0123";a = stoull(str, NULL, 16);   cout << "a = " << a << endl; //a = (3 + 2*16 + 1*16*16) = 291return 0;
}

stoull() 函数指定转换字符串为八进制用法

stoul.cpp

#include <iostream>
#include <string>
#include <limits.h>
using namespace std;int main(int argc, char *argv[])
{unsigned long long a; //x86_64构架下，unsigned long long 8个字节size_t pos = 0;string str;cout << "ULLONG_MAX = " << ULLONG_MAX << endl;/*数据在内存中是以补码的形式存储的，负数的补码等于反码加1-1的原码是：10000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001-1的反码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111110-1的补码是：11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111-1转成unsigned long long：(最大值) +（负数）+ 1-1转成unsigned long long：((2^64) - 1) + (-1) + 1*/str = "0x123";a = stoul(str, NULL, 8); //base = 8，指定八进制cout << "a = " << a << endl; //a = 0str = "0123"; //(3 + 2*8 + 1*8*8)a = stoul(str, NULL, 0); //base = 0，自动检测数值进制cout << "a = " << a << endl; //a = (3 + 2*8 + 1*8*8) = 83str = "-12";a = stoul(str, &pos, 8); //-(2 + 1*8)cout << "a = " << a << endl; //a = ((2^64) - 1) + (-10) + 1cout << "pos = " << pos << endl; //pos = 3str = "12";a = stoul(str, &pos, 8); //2 + 1*8cout << "a = " << a << endl; //a = 10cout << "pos = " << pos << endl; //pos = 2str = "  -12  35"; a = stoul(str, &pos, 8); //会舍弃空白符cout << "a = " << a << endl; //a = ((2^64) - 1) + (-10) + 1cout << "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;
}

总结：

stoul 函数：将字符串转成 unsigned long 整数。

stoull 函数：将字符串转成 unsigned long long 整数。

使用时需要注意的是 stoul、stoull 函数是 C++11标准加入的，用 g++ 编译器编译时需要加参数：-std=c++11

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