顺移加密

#include <iostream>#define CRYPT_OK 1#define CRYPT_ERROR 0#define PUSH_BACK 2using namespace std;const int a = int('a');const int z = int('z');const int A = int('A');const int Z = int('Z');string str;string cryptstr ;string decryptstr ;int init(string strr){    str =strr;    cryptstr = str;    decryptstr =str;}int encrypt(){    int index=0;    int push_back = PUSH_BACK;    while(str[index])    {        if(int(str[index])<=z&&int(str[index])>=a)        {            if(int(str[index])+push_back>z)                cryptstr[index] = char(int(str[index])-(z-a)+push_back);            else                cryptstr[index] = char(int(str[index])+push_back);        }        else if(int(str[index])<=Z&&int(str[index])>=A)        {            if(int(str[index])+push_back>Z)                cryptstr[index] = char(int(str[index])-(Z-A)+push_back);            else                cryptstr[index] = char(int(str[index])+push_back);        }        else            cryptstr[index] =str[index];        index++;    }    return 1;}int decrypt(){    int index=0;    int push_back = PUSH_BACK;    while(cryptstr[index])    {        if(int(cryptstr[index])<=z&&int(cryptstr[index])>=a)        {            if(int(cryptstr[index])-push_back<a)                decryptstr[index] = char(int(cryptstr[index])+(z-a)-push_back);            else                decryptstr[index] = char(int(cryptstr[index])-push_back);        }        else if(int(cryptstr[index])<=Z&&int(cryptstr[index])>=A)        {            if(int(cryptstr[index])-push_back<A)                decryptstr[index] = char(int(cryptstr[index])+(Z-A)-push_back);            else                decryptstr[index] = char(int(cryptstr[index])-push_back);        }        else            decryptstr[index] =cryptstr[index];        index++;    }    return 1;}int main(){    init("Hello world");    cout<<"加密移位:"<<PUSH_BACK<<endl;    cout << "原字符串:" << str<<endl;    if(encrypt())    {        cout<<"加密成功"<<endl;    }    cout << "加密后字符串:" << cryptstr<<endl;    if(decrypt())    {        cout<<"解密成功"<<endl;    }    cout << "解密后字符串:" << decryptstr<<endl;    return 0;}