C++ 如何在c ++中获取字符串的哈希码
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how to get hash code of a string in c++
提问by sufyan siddique
Following java code returns hash code of a string.
以下 java 代码返回字符串的哈希码。
String uri = "Some URI"
public int hashCode() {
return uri.hashCode();
}
I want to translate this code to c++. Is there any function availabe in c++ or an easy way to translate this.
我想将此代码转换为 C++。在 C++ 中是否有任何可用的函数或一种简单的方法来翻译它。
采纳答案by tune2fs
Boost provides a hash function:
Boost 提供了一个哈希函数：
#include <boost/functional/hash.hpp>
int hashCode()
{
boost::hash<std::string> string_hash;
return string_hash("Hash me");
}
回答by Cat Plus Plus
In C++03, boost::hash. In C++11, std::hash.
在 C++03 中，boost::hash. 在 C++11 中，std::hash.
std::hash<std::string>()("foo");
回答by tune2fs
The following is the source for the default String.hashCode()in Java, this is a trival exercise to implement in C++.
以下是String.hashCode()Java 中默认值的源代码，这是在 C++ 中实现的一个简单练习。
public int hashCode()
{
int h = hash;
if (h == 0 && count > 0)
{
int off = offset;
char val[] = value;
int len = count;
for (int i = 0; i < len; i++)
{
h = 31*h + val[off++];
}
hash = h;
}
return h;
}
回答by Megatron
Personally, I like to use boost's hash functions
就个人而言，我喜欢使用 boost 的哈希函数
http://www.boost.org/doc/libs/1_47_0/doc/html/hash.html
http://www.boost.org/doc/libs/1_47_0/doc/html/hash.html
making a string hash is pretty simple,
制作字符串哈希非常简单，
boost::hash<std::string> string_hash;
std::size_t h = string_hash("Hash me");
newer versions of C++ have an equivalent with std::hash
较新版本的 C++ 与 std::hash 等效
回答by Javier Gonzalez
//For C++ Qt you can use this code, the result is the sames as for Java hashcode()
//对于C++ Qt你可以使用这个代码，结果和Java hashcode()一样
int hashCode(QString text){
int hash = 0, strlen = text.length(), i;
QChar character;
if (strlen == 0)
return hash;
for (i = 0; i < strlen; i++) {
character = text.at(i);
hash = (31 * hash) + (character.toAscii());
}
return hash;
}
回答by Aero
I encoutered the same question as you have, hope this code will help you :
我遇到了和你一样的问题，希望这段代码能帮助你：
int HashCode (const std::string &str) {
int h = 0;
for (size_t i = 0; i < str.size(); ++i)
h = h * 31 + static_cast<int>(str[i]);
return h;
}
