C++ 将十六进制转换为十进制
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Converting Hexadecimal to Decimal
提问by zeulb
I'm looking for a way to convert hex(hexadecimal)to dec(decimal)easily. I found an easy way to do this like :
我正在寻找一种轻松将hex（十六进制）转换为dec（十进制）的方法。我找到了一个简单的方法来做到这一点：
int k = 0x265;
cout << k << endl;
But with that I can't input 265. Is there anyway for it to work like that:
但是我无法输入265. 无论如何，它是否可以这样工作：
Input: 265
输入： 265
Output: 613
输出： 613
Is there anyway to do that ?
有没有办法做到这一点？
Note:I've tried:
注意：我试过：
int k = 0x, b;
cin >> b;
cout << k + b << endl;
and it doesn't work.
它不起作用。
回答by smichak
#include <iostream>
#include <iomanip>
int main()
{
int x, y;
std::stringstream stream;
std::cin >> x;
stream << x;
stream >> std::hex >> y;
std::cout << y;
return 0;
}
回答by hmjd
回答by Christos
Here is a solution using strings and converting it to decimal with ASCII tables:
这是一个使用字符串并使用 ASCII 表将其转换为十进制的解决方案：
#include <iostream>
#include <string>
#include "math.h"
using namespace std;
unsigned long hex2dec(string hex)
{
unsigned long result = 0;
for (int i=0; i<hex.length(); i++) {
if (hex[i]>=48 && hex[i]<=57)
{
result += (hex[i]-48)*pow(16,hex.length()-i-1);
} else if (hex[i]>=65 && hex[i]<=70) {
result += (hex[i]-55)*pow(16,hex.length( )-i-1);
} else if (hex[i]>=97 && hex[i]<=102) {
result += (hex[i]-87)*pow(16,hex.length()-i-1);
}
}
return result;
}
int main(int argc, const char * argv[]) {
string hex_str;
cin >> hex_str;
cout << hex2dec(hex_str) << endl;
return 0;
}
回答by stefanl
Well, the C way might be something like ...
好吧，C 方式可能类似于...
#include <stdlib.h>
#include <stdio.h>
int main()
{
int n;
scanf("%d", &n);
printf("%X", n);
exit(0);
}
回答by 101dolmations
std::cout << "Enter decimal number: " ;
std::cin >> input ;
std::cout << "0x" << std::hex << input << '\n' ;
if your adding a input that can be a boolean or float or int it will be passed back in the int main function call...
如果您添加的输入可以是布尔值或浮点数或整数，它将在 int 主函数调用中传回...
With function templates, based on argument types, C generates separate functions to handle each type of call appropriately. All function template definitions begin with the keyword template followed by arguments enclosed in angle brackets < and >. A single formal parameter T is used for the type of data to be tested.
使用函数模板，基于参数类型，C 生成单独的函数来适当地处理每种类型的调用。所有函数模板定义都以关键字 template 开头，后跟括在尖括号 < 和 > 中的参数。单个形式参数 T 用于要测试的数据类型。
Consider the following program where the user is asked to enter an integer and then a float, each uses the square function to determine the square. With function templates, based on argument types, C generates separate functions to handle each type of call appropriately. All function template definitions begin with the keyword template followed by arguments enclosed in angle brackets < and >. A single formal parameter T is used for the type of data to be tested.
考虑以下程序，其中要求用户输入一个整数，然后输入一个浮点数，每个程序都使用 square 函数来确定平方。使用函数模板，基于参数类型，C 生成单独的函数来适当地处理每种类型的调用。所有函数模板定义都以关键字 template 开头，后跟括在尖括号 < 和 > 中的参数。单个形式参数 T 用于要测试的数据类型。
Consider the following program where the user is asked to enter an integer and then a float, each uses the square function to determine the square.
考虑以下程序，其中要求用户输入一个整数，然后输入一个浮点数，每个程序都使用 square 函数来确定平方。
#include <iostream>
using namespace std;
template <class T> // function template
T square(T); /* returns a value of type T and accepts type T (int or float or whatever) */
void main()
{
int x, y;
float w, z;
cout << "Enter a integer: ";
cin >> x;
y = square(x);
cout << "The square of that number is: " << y << endl;
cout << "Enter a float: ";
cin >> w;
z = square(w);
cout << "The square of that number is: " << z << endl;
}
template <class T> // function template
T square(T u) //accepts a parameter u of type T (int or float)
{
return u * u;
}
Here is the output:
Enter a integer: 5
The square of that number is: 25
Enter a float: 5.3
The square of that number is: 28.09
回答by dimon4eg
I use this:
我用这个：
template <typename T>
bool fromHex(const std::string& hexValue, T& result)
{
std::stringstream ss;
ss << std::hex << hexValue;
ss >> result;
return !ss.fail();
}
