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I have this function that decrypts a caesar encrypted message with a certain key and it gives me the right letters for the output but theres some weird blackspace after it.

Here's the function:

#include <iostream>
#include <string.h>
#include "proj1.h"
#include <cstdlib>
using namespace std;

int main()
{

  char dec[MAXMSGLEN];


  int i = 0;

  while(i < NUMMSGS){
    char solve = SolveCipher(cipher[i], dec);


      if(solve == '\0')
        {
          cout  << "Message #" << (i + 1) << " was not intertesting. " <<endl;
        }
      else
        {
          cout << "Message #" << (i + 1) << ",Key " << solve << endl;
          cout << "\t" << dec << endl;
        }


      i++;

  }


  return 0;
}

void Decipher(char cip[], char key){

  for(int i = 0; i < MAXMSGLEN && cip[i] != '\0'; i++){
    if (cip[i] != ' '){
      cip[i] = char(cip[i] - ((key - 'A')% 26));
      if (cip[i] < 65){
        cip[i] = ((65 - cip[i])-90);

      }

    }
    else{
      cip[i] = cip[i];
    }

  }
}


char SolveCipher(const char cip[], char dec[]){

  char msg[MAXMSGLEN];
  char check[MAXMSGLEN];
  char word[MAXCRIBLEN];

  //Deciphers message with every key
  for(char i = 'A'; i <= 'Z'; i++){

    //clears msg
    memset(msg, 0, (sizeof(msg)/sizeof(msg[0])));


    //stores cip in msg
    for(int j = 0; cip[j] != '\0'; j++){
      msg[j] = cip[j];
    }

    Decipher(msg, i);
    cout<< msg <<endl;
  }
  return '\0';
}

Here's the encrypted keys I have to loop through:

const char cipher[NUMMSGS][MAXMSGLEN] = {
  "HAAHJR HA KHDU AVTVYYVD",
  "DHFGS NBKNBJ ZMC ZKK HR VDKK",
  "Q PIDM JQMJMZ NMDMZ",
  "JCTFGT DGVVGT HCUVGT UVTQPIGT",
  "LRPYE I HTWW XPPE JZF LE ESP NZXXZYD",
  "KLSQ GML LGG DSLW YGL FGLZAF AF EQ TJSAF",
  "QEBC GUR ZVPEBSVYZ ORUVAQ GUR FGNGHR",
  "GZSGZWD NX XTRJBMJWJ JQXJ FY UWJXJSY",
  "RZVOCZM AJM OJHJMMJR HJMIDIB RVMH RDOC GJR XGJPYN",
  "ROBO MYWO LKN XOGC DKVUSXQ DRSC KXN DRKD"
};

And FYI I need to keep the parameters as they are now. I cannot change them to strings or anything like that.

If I brute force loop through the black spaces come inside the words

ROBO MYWO LKN XOGC DKVUSXQ DRSC KXN DRKD
QNAN LXVN KJM WNFB CJUTRWP CQRB JWM CQJC
PM▒M KWUM JIL VMEA BITSQVO BPQA IVL BPIB
OL▒L JVTL IHK ULD▒ AHSRPUN AOP▒ HUK AOHA
NK▒K IUSK HGJ TKC▒ ▒GRQOTM ▒NO▒ GTJ ▒NG▒
MJ▒J HTRJ GFI SJB▒ ▒FQPNSL ▒MN▒ FSI ▒MF▒
LI▒I GSQI FEH RIA▒ ▒EPOMRK ▒LM▒ ERH ▒LE▒
KH▒H FRPH EDG QH▒▒ ▒DONLQJ ▒KL▒ DQG ▒KD▒
JG▒G EQOG DCF PG▒▒ ▒CNMKPI ▒JK▒ CPF ▒JC▒
IF▒F DPNF CBE OF▒▒ ▒BMLJOH ▒IJ▒ BOE ▒IB▒
HE▒E COME BAD NE▒▒ ▒ALKING ▒HI▒ AND ▒HA▒
GD▒D BNLD A▒C MD▒▒ ▒▒KJHMF ▒GH▒ ▒MC ▒G▒▒
FC▒C AMKC ▒▒B LC▒▒ ▒▒JIGLE ▒FG▒ ▒LB ▒F▒▒
EB▒B ▒LJB ▒▒A KB▒▒ ▒▒IHFKD ▒EF▒ ▒KA ▒E▒▒
DA▒A ▒KIA ▒▒▒ JA▒▒ ▒▒HGEJC ▒DE▒ ▒J▒ ▒D▒▒
C▒▒▒ ▒JH▒ ▒▒▒ I▒▒▒ ▒▒GFDIB ▒CD▒ ▒I▒ ▒C▒▒
B▒▒▒ ▒IG▒ ▒▒▒ H▒▒▒ ▒▒FECHA ▒BC▒ ▒H▒ ▒B▒▒
A▒▒▒ ▒HF▒ ▒▒▒ G▒▒▒ ▒▒EDBG▒ ▒AB▒ ▒G▒ ▒A▒▒
▒▒▒▒ ▒GE▒ ▒▒▒ F▒▒▒ ▒▒DCAF▒ ▒▒A▒ ▒F▒ ▒▒▒▒
▒▒▒▒ ▒FD▒ ▒▒▒ E▒▒▒ ▒▒CB▒E▒ ▒▒▒▒ ▒E▒ ▒▒▒▒
▒▒▒▒ ▒EC▒ ▒▒▒ D▒▒▒ ▒▒BA▒D▒ ▒▒▒▒ ▒D▒ ▒▒▒▒
▒▒▒▒ ▒DB▒ ▒▒▒ C▒▒▒ ▒▒A▒▒C▒ ▒▒▒▒ ▒C▒ ▒▒▒▒
▒▒▒▒ ▒CA▒ ▒▒▒ B▒▒▒ ▒▒▒▒▒B▒ ▒▒▒▒ ▒B▒ ▒▒▒▒
▒▒▒▒ ▒B▒▒ ▒▒▒ A▒▒▒ ▒▒▒▒▒A▒ ▒▒▒▒ ▒A▒ ▒▒▒▒
▒▒▒▒ ▒A▒▒ ▒▒▒ ▒▒▒▒ ▒▒▒▒▒▒▒ ▒▒▒▒ ▒▒▒ ▒▒▒▒
▒▒▒▒ ▒▒▒▒ ▒▒▒ ▒▒▒▒ ▒▒▒▒▒▒▒ ▒▒▒▒ ▒▒▒ ▒▒▒▒

Any ideas on this one?

4

2 に答える 2

0

あなたの問題は、文字列の値を「ずっと」に変更していることですMAXMSGLEN。ここで、メッセージの本文 (たとえば 10 文字) を復号​​化し、停止せずに続行し、範囲外の値を更新します。

修正は、「文字列の終わり」の null-terminator が表示されたら停止することです'\0。

void Decipher(char cip[], char key){

    for(int i = 0; i < MAXMSGLEN && cip[i] != '\0'; i++){
    if (cip[i] != ' '){
      cip[i] = char(cip[i] - ((key - 'A')% 26));
      if (cip[i] < 65){
          cip[i] = ((65 - cip[i])-90);
        }
    }
  }
}

または、より読みやすいコードを好む場合 (ループの制御ブロックに詰め込みすぎないでください):

void Decipher(char cip[], char key){

    for(int i = 0; i < MAXMSGLEN; i++){
    if(cip[i] == '\0'){
        break; // end the loop once we reached the string terminator
    }
    if (cip[i] != ' '){
      cip[i] = char(cip[i] - ((key - 'A')% 26));
      if (cip[i] < 65){
          cip[i] = ((65 - cip[i])-90);
        }
    }
  }
}

更新65:やのような「マジック ナンバー」の使用は避けてください90。'A'代わりにandを使用すると、コードが理解しやすくなります'Z'。固定解読関数は次のとおりです。

void Decipher(char cip[], char key){

    for(int i = 0; i < MAXMSGLEN; i++){
    if(cip[i] == '\0'){
        break; // end the loop once we reached the string terminator
    }
    if (cip[i] != ' '){
      cip[i] = char(cip[i] - ((key - 'A')% 26));
      if (cip[i] < 'A'){
          cip[i] = ('Z' - ('A' - cip[i])); // <-- this is where you were getting negative values
        }
    }
  }
}
于 2015-09-24T22:12:35.580 に答える
0

文字列を次のように渡すだけstringです。

void Decipher(std::string& cip, char key) {
  for (char& ch : cip) {
    if (ch != ' ') {
      ch = char(ch - ((key - 'A') % 26));
      if (ch < 65) {
        ch = ((65 - ch)-90);
      }
    }
  }
}

このようにして、その長さに関する情報も渡され、文字の範囲ベースのループを簡単に実行できます。

于 2015-09-24T22:12:46.977 に答える