6月25日代码

template<typename T>
void swap(T &a,T &b)
{
    T temp=a;
    a=b;
    b=temp;
}
int add(double a,double b)
{
    return a+b;
}
int main()
{
    int ia=3;
    double db=5.0;
    char s1[]="good",s2[]="better";
    int x=add(ia,db);
    /*swap(ia,db);
    swap(s1,s2);*/
}
//-------------------
template<typename T>
T max(T a,T b)
{
    return a<b?b:a;
}
//const T&a与T const&a等价
//----------------------------------------
#include<iostream>
template<typename T>
T const& max(T const& a,T const& b)
{
    return a<b?b:a;
}
int main()
{
    int ia=3;
    double db=5.0;
    std::cout<<max<double>(ia,db)<<"
";
    std::cout<<max(static_cast<double>(ia),db)<<"
";
}
//--------------------------------------------
#include<iostream>
template<typename T>
void swap(T &a,T&b)
{
    T temp=a;
    a=b;
    b=temp;
}
int main()
{
    int ia=3;
    const int cb=5;
    swap(ia,7);
    swap<int>(ia,7);
    swap(cb,7);
    swap<const int>(ia,7);
}
//----------------
const char*const& max(const char*const&a,const char* const&b)
{
    return std::strcmp(a,b)<0?b:a;
}
//------------------
void f(int *ix,int *iy,double *dx,double *dy)
{
    int *ip=max(ix,iy);
    double *dp=max(dx,dy);
}
//-----------------------------------
#include<iostream>
template<typename T>
T const& max(T const&a,T const&b)
{
    return a<b?b:a;
}
template<typename T>
T*const& max(T*const&a,T*const&b)
{
    return *a<*b?b:a;
}
const char*const&max(const char* const&a,const char*const&b)
{
    return std::strcmp(a,b)<0?b:a;
}
int main()
{
    int ia=3,ib=7;
    char*s1="hello";
    char*s2="hell";
    std::cout<<*max(&ia,&ib)<<"
";
    std::cout<<max(s1,s2)<<"
";
    std::cout<<max(ia,ib)<<"
";
}

//
#include <iostream>
#include <string>
#include <fstream>
#include <vector> // 向量头文件
using namespace std;
string co(string message,string code);
string deco(string cipher,string code);
int main()
{ 
    ifstream finm("message.txt"); //原文
    //string message;
    vector<string> messageAll; 
    string msgtemp;
    string cipher,decipher;
    string code;
    ifstream fin("code.txt"); //加密秘钥
    
    for ( ;getline(finm, msgtemp); )
    {
        messageAll.push_back(msgtemp); //将输入的所有字符分行读、存储
    }                
    
    cout<<"文件读入结束
"<<endl;    
    int row=messageAll.size(); //读入了多少行    
    for (int i=0; i<row; i++)
    {
        msgtemp=messageAll[i];
        cout<<"第"<<i+1<<"行字符串为"<<msgtemp<<endl; //原文
        fin>>code; //读入一行，加密秘钥        
        cipher=co(msgtemp,code); //函数调用        
        cout<<"第"<<i+1<<"行字符串加密后得到"<<cipher<<endl; //加密
        decipher=deco(cipher,code);
        cout<<"对"<<i+1<<"行密加密后的字符串，解密后得到"<<decipher<<endl; //解密
        cout<<endl;
    }        
    return 0;
}
string co(string message,string code)
{
    int n;
    n=message.length();
    for(int i=0;i<n;i++)
    {  
        message[i]=message[i]+code[i]-'0';
        if(message[i]>'z')
        {
            message[i]=message[i]-('z'-' ');            
        }
        
        
    } return message;
}
string deco(string cipher ,string code)
{
    int n;
    n=cipher.length();
    for(int i=0;i<n;i++)
    {   
        cipher[i]=cipher[i]+('z'-' ');
        if(cipher[i]>'z')
        {
            cipher[i]=cipher[i]+('z'-' ');
        }
        cipher[i]=cipher[i]-('z'-' ');
        cipher[i]=cipher[i]-code[i]+'0';
        
    }    
    return cipher;
}

//=====================================
// 101_5.cpp
// 字符的加密解密
//=====================================
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
using namespace std;
//---------------------------------------
string encode(string &str);    //函数声明
string decode(string &trans);  //函数声明
const char key[]="4962873";
//---------------------------------------
int main(){    
    string str;
    cout<<"请输入需要加密的一行字符，以换行结束"<<endl;
    getline(cin, str);
    string trans=encode(str);//加密函数encode,加密得到trans
    cout<<"加密后,密文为："<<endl;
    cout<<trans<<endl;
    if (str==decode(trans)) //解密函数decode,判断解密得到的序列是否与原始输入序列相等
    {    
        cout<<"解密成功,原文为："<<endl;
        cout<<str<<endl;
    }
    else
        cout<<"解密失败"<<endl;    
    return 0;
}
//-------------------------------------

string encode(string &str)
{
//    string result(str); //类似于int a(5); 将字符串类型变量result赋值为str
    string result;      //这种方法是通过assign函数来指定
    result.assign(str);//用于拷贝、赋值操作
    
    for (int i=0;i<str.length(); i++)
    {
        result[i]+=key[i%7]-'0';
        if (result[i]>'z')
            result[i]=result[i]-('z'-' '+1);//大写字母和小写字母 差 65-32+1,空格是 32  
        
    }
    return result;
}
//-------------------------------------
string decode(string &str)
{
    string result (str);
    for (int i=0;i<str.length(); i++)
    {
        result[i]-=key[i%7]-'0';
        if (result[i]<' ')
            result[i]=result[i]+('z'-' '+1);
        
    }
    return result;
}

//=====================================
// 钱能教材P101_5.cpp
// 字符的加密解密
//=====================================
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
using namespace std;
//---------------------------------------
string encode(string &str);    //函数声明
string decode(string &trans);  //函数声明
const char key[]="4962873";
//---------------------------------------
int main(){    
    string str;
    cout<<"请输入需要加密的一行字符，以换行结束"<<endl;
    getline(cin, str);
    string trans=encode(str);//加密函数encode,加密得到trans
    cout<<"加密后,密文为："<<endl;
    cout<<trans<<endl;
    if (str==decode(trans)) //解密函数decode,判断解密得到的序列是否与原始输入序列相等
    {    
        cout<<"解密成功,原文为："<<endl;
        cout<<str<<endl;
    }
    else
        cout<<"解密失败"<<endl;    
    return 0;
}
//-------------------------------------

string encode(string &str)
{
//    string result(str); //类似于int a(5); 将字符串类型变量result赋值为str
    string result;      //这种方法是通过assign函数来指定
    result.assign(str);
    
    for (int i=0;i<str.length(); i++)
    {
        result[i]+=key[i%7]-'0';
        if (result[i]>'z')
            result[i]=result[i]-('z'-' '+1);//' '代表32，" "不是32
        
    }
    return result;
}
//-------------------------------------
string decode(string &str)
{
    string result (str);
    for (int i=0;i<str.length(); i++)
    {
        result[i]-=key[i%7]-'0';
        if (result[i]<' ')
            result[i]=result[i]+('z'-' '+1);
        
    }
    return result;
}