1 std::stoul

将字符串转换为无符号整数。解析 str ,将其内容解释为指定基数的整数，该基数作为无符号长整型值返回。

unsigned long stoul (const string&  str, size_t* idx = 0, int base = 10);
Parameters :
str : String object with the  representation of an integral number.idx : Pointer to an object of type size_t, whose value is set by the function to position of the next character in str after the numerical value.
This parameter can also be a null pointer, in which case
it is not used.base : Numerical base (radix) that determines the valid characters and their interpretation.
If this is 0, the base used is determined by the format in
the sequence.Notice that by default this argument is 10, not 0.

2 std::stoull

将字符串转换为 unsigned long long。解析 str 将其内容解释为指定基数的整数，该基数作为 unsigned long long 类型的值返回。

unsigned long long stoull
(const string&  str, size_t* idx = 0, int base = 10);
Parameters :
str : String object with the representation of an integral number.idx : Pointer to an object of type size_t, whose value is set by the function to position of the next  character in str after the numerical value. This parameter can  also be a null pointer, in which case it is not used.base : Numerical base (radix) that determines  the valid characters and their interpretation.
If this is 0, the base used is determined by the format in the
sequence. Notice that by default this argument is 10, not 0.

3 实例解析

Input : FF
Output : 255Input : FFFFF
Output :16777215

// CPP code to convert hexadecimal
// string to int
#include <bits/stdc++.h>
using namespace std;int main()
{// Hexadecimal stringstring str = "FF";// Converted integerunsigned long num = stoul(str, nullptr, 16);// Printing the integercout << num << "\n";// Hexadecimal stringstring st = "FFFFFF";// Converted long longunsigned long long val = stoull(st, nullptr, 16);// Printing the long longcout << val;return 0;
}

另一个例子：比较两个包含十六进制值的字符串的程序这里使用stoul，但在数字超过 unsigned long 值的情况下，使用stoull。

// CPP code to compare two
// hexadecimal string
#include <bits/stdc++.h>
using namespace std;int main()
{// Hexadecimal stringstring s1 = "4F";string s2 = "A0";// Converted integerunsigned long n1 = stoul(s1, nullptr, 16);unsigned long n2 = stoul(s2, nullptr, 16);// Compare both stringif (n1 > n2)cout << s1 << " is greater than " << s2;else if (n2 > n1)cout << s2 << " is greater than " << s1;elsecout << "Both " << s1 << " and " << s2 << " are equal";return 0;
}

输出：A0 is greater than 4F

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c++中将字符串转换为无符号整数函数：std::stoul and std::stoull

文章目录

1 std::stoul

2 std::stoull

3 实例解析

c++中将字符串转换为无符号整数函数：std::stoul and std::stoull相关推荐

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