将字符串存储在unsigned long int的向量中 [英] Store a string in a vector of unsigned long int

问题描述

我想将 std :: string 转换为 std :: vector< unsigned long int> ，并能够逆转它。目前，我这样做：

  std :: string str =Hello World！ 
 std :: vector< unsigned long int>键; 
 for（unsigned long int i = 0; i  {
 unsigned long int key = 0; 
 for（unsigned long int j = 0; j< sizeof（unsigned long int）&& i< str.length（）; ++ i，++ j）
 {
 unsigned char uchar_value = static_cast< unsigned char>（str [i]）; 
 unsigned long int ulong_value = static_cast< unsigned long int>（uchar_value）; 
 key | = ulong_value<< （j * CHAR_BIT）; 
} 
 keys.push_back（key）; 
} 
  

然后，我有一个类似的过程。但它是相当丑陋！ 有更好/更优雅的方式吗？可能直接使用 memcpy 吗？

$ p

<$>

解决方案

p $ p> std :: string str =Hello World！;
std :: vector< unsigned long int> keys（str.size（）/ sizeof（unsigned long int）+1）;

std :: copy（begin（str），end（str），reinterpret_cast< unsigned char *>（&（* keys.begin（））））;


反之：

  std :: string str2（keys.size（）* sizeof（unsigned long int），'\0'）; 
 std :: copy（reinterpret_cast< unsigned char *>（& * begin（keys）），reinterpret_cast< unsigned char *>（& * end（keys）），str2.begin（））; 
 str2.resize（str.size（））; 
  

如果要以相反的顺序存储字节，可以使用反向迭代器：

  std :: string str =Hello World！ 
 std :: vector< unsigned long int> keys（str.size（）/ sizeof（unsigned long int）+1）; 
 
 std :: copy（str.rbegin（），str.rbegin，reinterpret_cast< unsigned char *>（&（* keys.begin（））））; 
  

I would like to convert a std::string into a std::vector<unsigned long int>, and be able to reverse it. Currently, I do this by this way :

std::string str = "Hello World !";
std::vector<unsigned long int> keys;
for(unsigned long int i = 0; i < str.length();)
{
  unsigned long int key = 0;
  for(unsigned long int j = 0; j < sizeof(unsigned long int) && i < str.length(); ++i,++j)
  {
    unsigned char uchar_value = static_cast<unsigned char>(str[i]);
    unsigned long int ulong_value = static_cast<unsigned long int>(uchar_value);
    key |= ulong_value << (j * CHAR_BIT);
  }
  keys.push_back(key);
}

Then, I have a similar procedure to reverse it. But it's quite ugly ! Is there a better/more elegant way to do it ? Maybe directly with memcpy ? But I don't see how.

解决方案

What about:

std::string str = "Hello World !";
std::vector<unsigned long int> keys(str.size() / sizeof(unsigned long int)+1);

std::copy(begin(str), end(str), reinterpret_cast<unsigned char*>(&(*keys.begin())));

And the reverse:

std::string str2(keys.size()*sizeof(unsigned long int), '\0');
std::copy(reinterpret_cast<unsigned char*>(&*begin(keys)), reinterpret_cast<unsigned char*>(&*end(keys)), str2.begin());
str2.resize(str.size());

And if you want to store the bytes in reverse order, you can use reverse iterators:

std::string str = "Hello World !";
std::vector<unsigned long int> keys(str.size() / sizeof(unsigned long int)+1);

std::copy(str.rbegin(), str.rbegin, reinterpret_cast<unsigned char*>(&(*keys.begin())));  

这篇关于将字符串存储在unsigned long int的向量中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！