Program 215:Encryption using Polybius Cipher in C

Program 214: Polybius Square in detail
 

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<ctype.h>
main()
{
 int i,j,poly[26],x,k;
 char str[1000];
 printf("Enter a sentence\n");
 gets(str);
i=0;
 while(str[i]!='\0')
 {
  if((str[i]>=0&&str[i]<=31)||(str[i]>=33&&str[i]<65)||(str[i]>90&&str[i]<97)||(str[i]>122&&str[i]<=127))
  {
   printf("Enter only alphabets and space\n");
   exit(0);
  }
  i++;
 }
 x=0;
 k=11;
 //Assigning Polybius Square numbers to alphabets
 
for(i=0;i<=25;i++)
{
 if(i<=8)
 {
      if(i%5==0&&i!=0)
   {
  k+=5;
  poly[x]=k++;
 
    }
   else{
  poly[x]=k++;
  
      }
 }
 if(i>=10)
 {
      if(i%5==0&&i!=0)
   {
 
  poly[x]=k++;
   k+=5;
 
    }
   else{
  poly[x]=k++;
  
      }  
 }
 if(i==9)
 {
  poly[x]=24;
 }
 
  
  x++;
}
i=0;
printf("Encrypted Code using Polybius Square Cipher \n");
while(str[i]!='\0')
  {
 if(!((str[i]>=0&&str[i]<=31)||(str[i]>=33&&str[i]<65)||(str[i]>90&&str[i]<97)||(str[i]>122&&str[i]<=127)))
 {
   if(str[i]>='A'&&str[i]<='Z')
   {
    printf("%d ",poly[str[i]-'A']); 
   }
     if(str[i]>='a'&&str[i]<='z')
     {
      printf("%d ",poly[str[i]-'a']);
     }
      
 } 
    
    if(str[i]==' ')
    {
      printf("%c",str[i]);    
    }
    
   i++;
  }
  printf("\n");
 
}

Explanation:

Polybius Square :

 Means A-11, F-21,N-33 and so on.

//Coming Soon

Output:
After 1st run:

 After 2nd run: