Question

I need help implementing the following code without using filehandling and only getchar(); this is the prompt

"The input for your program will be a text file containing a large amount of English. Typically, an English sentence ends with a period (aka, dot). Many years ago, when people used mechanical typewriters, the proper form was to place one space between words in a sentence, but two spaces after the period at the end of the sentence. This rule is no longer taught, since word processors automatically control spacing. Your program must extract the “secret message” from the input file. The message is hidden inside the file using the following scheme. The message is hidden in binary notation, as a sequence of 0’s and 1’s. Each block of 8-bits is the ASCII encoding of a single character in the “secret message”. Your program will scan the input, and for each period (aka, dot) encountered, your program will count the number of spaces (ASCII 0x20) that immediately follow the dot. If the number of spaces is 0, then your program will ignore that dot completely. If the number of spaces is 1, then that corresponds to a single 0 bit of the secret message. If the number of spaces is 2, then that corresponds to a single 1 bit of the secret message. Finally, if the number of spaces is 3 or more, then that indicates that there are no more characters in the secret message. Your program must scan the input file, and output to stdout the plain text secret message. If your program successfully completes its task, then the program should return an exit status of 0 to the operating system. If the number of bits in the message is not a multiple of 8 (8 bits for each ASCII character), then your program should return an exit status of 1. If the input file does not containing the “message over” signal, i.e., a dot followed by 3 or more spaces, then your program should return an exit status of 2."

and this is my code

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main(){
  
  
  
char ch;
int count = 0;
int secretMessage = 0;
int bit = 0;
int flag = 0;
  
while ((ch = getchar()) != EOF){

while ((ch = getchar()) == '.'){

while ((ch = getchar()) == ' '){

if(ch==' ') {   
count++;
}
else
{ break;}
}
  

if(count == 2){   
int mask=1<<bit;
secretMessage=secretMessage | mask;
bit++;
}
else if(count == 1)   
{
int mask=1<<bit;
secretMessage=secretMessage & mask;
bit++;

bit++;}
else if(count >= 3){   
flag = 1;
break;

if(bit == 8){
bit = 0;
printf("%c", secretMessage);
secretMessage = 0;
}
}

}

}

if(bit != 0){
return(1);
}
if(flag == 0){
return(2);
}
  
return 0;
}
  
i am not sure where i went wrong

  

Answer 1

Answer:-

#include<stdio.h>
#include<stdlib.h>
#include<math.h>

int main(){
  
   FILE *file;
   if( (file = fopen("cipher.txt", "r")) == NULL){       //open file
       printf("Error in opening file");
       exit(1);
   }
  
   char ch;
   int count = 0;
   int ascii = 0;
   int bit = 0;
   int flag = 0;
  
   while ((ch = fgetc(file)) != EOF){       //read a character
       if(ch == '.'){                   //if found a dot
           count = 0;
           while ((ch = fgetc(file)) != EOF){
               if(ch==' ')           //count no of spaces
                   count++;
               else
                   break;
           }
           if(count == 2){           //if 2 spaces present -- 1 bit
               ascii += pow(2,bit);
               bit++;
           }
           else if(count == 1)       //if 1 space present -- 0 bit
               bit++;
           else if(count >= 3){       //if more than 3 spaces present -- no more message
               flag = 1;
               break;
           }
       }
       if(bit == 8){
           bit = 0;
           printf("%c", ascii);       //print character of message when 8 bits are read
           ascii = 0;
       }
   }
  
   fclose(file);
  
   if(bit != 0){
       exit(1);
   }
   if(flag == 0){
       exit(2);
   }
  
   return 0;
}

If you find difficulty to understand the code, please let me know in comments tab below, Then I will provide another code or else i will any modifications in the present code. Hope it will helps you. Please give Thumbs Up!! Thank you for posting the question, All the best.