使用stringstream获取字节值 [英] Getting a byte value using stringstream

问题描述

我有这个（不正确的）示例代码，用于从stringstream获取值，并将其存储在一个字节大小的变量（它需要在一个单一字节var，而不是一个int）：

I've got this (incorrect) sample code for getting a value out of stringstream and storing it in a byte-sized variable (it needs to be in a single byte var, not an int):

#include <iostream>
#include <sstream>

using namespace std;

int main(int argc, char** argv)
{
    stringstream ss( "1" );

    unsigned char c;
    ss >> c;

    cout << (int) c << endl;
}

我运行时的输出是49，这不是我想要的查看。显然，这被视为一个char而不是简单的数值。什么是最c ++ ish的方式来获得c而持有1而不是49当被转换为int？

The output when I run this is 49, which is not what I would like to see. Obviously, this is being treated as a char and not simple numeric value. What is the most c++ish way to get c to hold a 1 rather than a 49 when casted to an int?

谢谢！

推荐答案

最C ++的方式肯定是通过读入另一个整数类型来正确解析值，然后 转换为字节类型（因为读入 char 永远不会解析 - 它总是只读取下一个字符）：

The most C++-ish way is certainly to parse the value properly by reading into another integral type, and then cast to a byte type (since reading into a char will never parse – it will always just read the next character):

typedef unsigned char byte_t;

unsigned int value;
ss >> value;
if (value > numeric_limits<byte_t>::max()) {
    // Error …
}

byte_t b = static_cast<byte_t>(value);

我使用了 unsigned int 最自然的，虽然未签名的短当然也可以工作。

I’ve used unsigned int since that’s the most natural, although unsigned short would of course also work.

这篇关于使用stringstream获取字节值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！