Vigenere

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December 2nd, 2012, 09:35 AM

Jeanjean

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Vigenere

Hello friends,

I need a help for my programming. When I get the Key, I did nothing appears on the screen.

Thanks !

Code:

#define CL 10 // Key length 
#define TX 110 //Word length
#include<stdio.h>
#include<string.h> //for strlen()

int main()
{
char txt [TX]={0};
char cle[CL]={0};
char txtkrypt[TX]={0};

int a,b,i,j,s; //variable of encryption



char grille [26][26]= {"abcdefghijklmnopqrstuvwxyz"};

printf("enter the text : ");
scanf("%s",txt);

printf("enter the key :");
scanf("%s",cle);
a=0;
b=0;
s=strlen(cle); 
do{
for(i=0;i<26;i++){ //incrementation of i
if(txt[a]==grille[0][i]){ 
for(j=0;j<26;j++){ //incrementation of j
if(cle[b]==grille[j][0]) 
txtkrypt[a]=grille[j][i]; 
                 }
                        }                        
                 }
a++; //incrementation of a (word character )
b++; //incrementation of b (character of key)
if(b==s)b=0; 
}
while(txt[a]!='\0'); //as a txt is not the end
printf("text crypt:\n%s\n\n\n\n",txtkrypt); 
return 0;
}

December 2nd, 2012, 12:02 PM

salem

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Nobody will care about your post, since your code is all on one line.

__________________
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December 2nd, 2012, 12:02 PM

Lux Perpetua

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Please reformat your code so that it isn't all on a single line.

December 2nd, 2012, 12:22 PM

Jeanjean

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Done! Sorry....

December 2nd, 2012, 02:14 PM

salem

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Indented code should look something like this.

Code:

#define CL 10                   // Key length
#define TX 110                  //Word length
#include<stdio.h>
#include<string.h>              //for strlen()

int main()
{
  char txt[TX] = { 0 };
  char cle[CL] = { 0 };
  char txtkrypt[TX] = { 0 };

  int a, b, i, j, s;            //variable of encryption



  char grille[26][26] = { "abcdefghijklmnopqrstuvwxyz" };

  printf("enter the text : ");
  scanf("%s", txt);

  printf("enter the key :");
  scanf("%s", cle);
  a = 0;
  b = 0;
  s = strlen(cle);
  do {
    for (i = 0; i < 26; i++) {  //incrementation of i
      if (txt[a] == grille[0][i]) {
        for (j = 0; j < 26; j++) {  //incrementation of j
          if (cle[b] == grille[j][0])
            txtkrypt[a] = grille[j][i];
        }
      }
    }
    a++;                        //incrementation of a (word character )
    b++;                        //incrementation of b (character of key)
    if (b == s)
      b = 0;
  }
  while (txt[a] != '\0');       //as a txt is not the end
  printf("text crypt:\n%s\n\n\n\n", txtkrypt);
  return 0;
}

Some problems.
1. char grille [26][26]= {"abcdefghijklmnopqrstuvwxyz"};
This only initialises the first ROW of your grille. All the other rows are full of \0.

2. scanf("%s", txt);
OK if all you input is "hello"
But if you try to input "The quick brown fox", then you're going to be disappointed.

December 3rd, 2012, 01:18 PM

Jeanjean

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Join Date: Dec 2012

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Vigenere

Thanks ! But how can I fix the problem ??

I try without the second grille, but for me the second grille is necessary no ?

Code:

#define CL 10                   // Key length
#define TX 110                  //Word length
#include<stdio.h>
#include<string.h>              //for strlen()

int main()
{
  char txt[TX] = { 0 };
  char cle[CL] = { 0 };
  char txtkrypt[TX] = { 0 };

  int a, b, i, j, s;            //variable of encryption



  char grille[26] = { "abcdefghijklmnopqrstuvwxyz" };

  printf("enter the text : ");
  scanf("%s", txt);

  printf("enter the key :");
  scanf("%s", cle);
  a = 0;
  b = 0;
  s = strlen(cle);
  do {
    for (i = 0; i < 26; i++) {  //incrementation of i
      if (txt[a] == grille[0]) {
        for (j = 0; j < 26; j++) {  //incrementation of j
          if (cle[b] == grille[j])
            txtkrypt[a] = grille[j];
        }
      }
    }
    a++;                        //incrementation of a (word character )
    b++;                        //incrementation of b (character of key)
    if (b == s)
      b = 0;
  }
  while (txt[a] != '\0');       //as a txt is not the end
  printf("text crypt:\n%s\n\n\n\n", txtkrypt);
  return 0;
}

December 4th, 2012, 12:35 AM

salem

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> for (i = 0; i < 26; i++) { //incrementation of i
> if (txt[a] == grille[0]) {
If txt[a] == grille[0] is false the first time around, then doing it a further 25 times isn't going to help.

http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher

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