string型哈希值的明氏距离比较

来源：互联网发布：白露级程序员编辑：程序博客网时间：2024/05/17 21:43

前一段时间在网上找以图搜图的资料，发现了感知哈希算法，得出的哈希值以字符串形式保存，我们管这种形式叫做哈希指纹。字符串中为十六进制数，需计算其二进制中的明氏距离，即二进制表示中不一样位数的个数。如下测试代码：

// test.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <iostream>using namespace std;int LSH(string str1,string str2);int sub(char a,char b);int _tmain(int argc, _TCHAR* argv[]){string str1 = "9e0f53";string str2 = "0b672a";cout<<"str1 = "<<str1.c_str()<<endl;cout<<"str2 = "<<str2.c_str()<<endl;int dis = LSH(str1,str2);cout<<"dis = "<<dis<<endl;int a;cin >> a;return 0;}int LSH(string str1,string str2){//int L = sizeof(str1.c_str());int L = str1.length();cout<<"L = "<<L<<endl;int dis  = 0;for(int i=0;i<L;i++){dis += sub(str1[i],str2[i]); }return dis;}unsigned char char2hex(char a){unsigned char t(0);switch(a){case 'a': t = 10; break;case 'b': t = 11; break;case 'c': t = 12; break;case 'd': t = 13; break;case 'e': t = 14; break;case 'f': t = 15; break;default: t = a - '0'; break;;}return t;}int sub(char a,char b){unsigned char a1 = char2hex(a);unsigned char b1 = char2hex(b);unsigned char c1 = a1^b1;cout<<"a1 = "<< (int)a1 <<endl;cout<<"b1 = "<< (int)b1 <<endl;//cout<<"c1 = "<< (int)c1 <<endl;int t(0);unsigned char tem(1);for(int i=0;i<8;i++){if(c1&(tem))t++;   tem = tem<<1;}cout<<"t = "<<(int)t <<endl;return t;}

运行结果：

<img src="http://img.blog.csdn.net/20140926140419752?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQveGF1dF96amI=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" style="font-family: Arial, Helvetica, sans-serif;" alt="" />

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