Simple encryption and decryption implementations---affine passwords (c + + uses string)

Using the String class in C + +, there is no limit to the length of the array compared to using the array, and the operation is convenient for adding

#include  <iostream> #include  <string>using namespace std;string jiami ( STRING&NBSP;STR,INT&NBSP;K,INT&NBSP;B); String jiemi (string pass,int k,int b);int  Canshu (int k,int b); Int main () {    string str;      //plaintext     string pass;    //ciphertext     string  res;        //Clear     int k,b;         //parameters of the cryptographic algorithm     cout<< "Please enter clear text:";     cin>>str;    cout<< "Please enter the parameters of the cryptographic algorithm (K&NBSP;B):";     cin>>k>>b;    while (!canshu (k,b))     {         cout<< "parameter is not in law (the parameters should be the prime number of mod 26), please re-enter:";         cin>>k>>b;    }    cout<< "encryption function: F (x) =" <<k<< "x+" << B<<endl;    pass=jiami (str,k,b);    cout<< "ciphertext:" << Pass<<endl;    res=jiemi (pass,k,b);    cout<< "decrypted plaintext after:" < <res<<endl;    return 0;} Int canshu (int k,int b) {    int c,t,mod = 26;     //die  26    if (k==1 | |  k%2==0)         return 0;    if (mod<k )     {        t=mod;         mod=k;        k=t;    }     while (c!=0)     {        c=mod%k;         mod=k;        k=c;     }    if (mod==1)         return  1;    else         return 0;} String jiami (string str,int k,int b) {    int i;     cout<< "\ n input the plaintext required to be encrypted:" <<str<<endl;    for (I=0;i<str.length (); i+ +)     {        int a;         a= (str[i]-97) *k+b;    //encryption          if (a>25)     //control for 0-25     mod to 26         {            do      //Guaranteed not to exceed domain             {                 a=a-26;                 }while (a>25);             a=a+97;        //the ASC code obtained after encryption;             str[i]= (char) a;         }        else         {            a=a+97;             str[i]= (char) a;         }    }        return  STR;} String jiemi (String&NBSP;PASS,INT&NBSP;K,INT&NBSP;B) {    int i;    for (i=0;i< Pass.length (); i++)                  //decryption Process     {        int d;         d= (pass[i]-97)-b;          while (d%k!=0)         {             d=d+26;        }         d=d/k;        pass[i]= (char) (d+97);     }    return pass;}

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Simple encryption and decryption implementations---affine passwords (c + + uses string)