Need help assignment

The aim of this program is to read a message on a file using fscanf and print it to another file while encrypting it by cycling it k number of places where k is user-defined from 0-9. So far I've written a large amount of code but I think there's something wrong with it because it's not scanning anything.

I'm supposed to encrypt the following:

abcdef uvwxyz ZYXWVUTS RQPONML 102378

by cycling it "k" number of places using the ASCII numbers

Code:

#include <stdio.h> FILE *f_in, *f_out; int var, k, status; char output, chrr; main() { printf("Enter a value from 0 to 9.\n"); scanf("%d", &k); if (k>=0 && k<=9) { f_in = fopen("message.txt", "r"); f_out = fopen("encrypted.txt", "w"); //status = fscanf (f_in, "%c", &var); //chrr = (int) input while (var != EOF) { fscanf(f_in, "%d", &var); fscanf(f_in, "%c", &chrr); if ((chrr>=48) && (chrr<=57)) { if (chrr==57) { if(k==0) { output=57; fprintf( f_out, "%c", output); printf("%c", output); } else { output=47+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==56) { if(k<=1) { output=56+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=46+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==55) { if(k<=2) { output=55+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=45+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==54) { if(k<=3){ output=54+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=44+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==53) { if(k<=4){ output=53+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=43+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==52) { if(k<=5){ output=52+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=42+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==51) { if(k<=6){ output=51+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=41+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==50) { if(k<=7){ output=50+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=40+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==49) { if(k<=8){ output=49+k; fprintf( f_out, "%c", output); printf("%c", output); } else { output=39+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr==48) { output=48+k; fprintf( f_out, "%c", output); printf("%c", output); } } else if ((chrr>='a') && (chrr<='z')) { if (chrr=='z') { if(k==0){ output=122; fprintf( f_out, "%c", output); printf("%c", output); } else { output=96+k; fprintf( f_out,"%c", output); printf("%c",output); } } if (chrr=='y') { if(k==0 || k==1) { output=121+k; fprintf( f_out, "%c", output); } else { output=95+k; fprintf( f_out, "%c", output); } } if (chrr=='x') { if(k>=0 && k<=2) { output=120+k; fprintf( f_out, "%c", output); } else { output=94+k; fprintf( f_out, "%c", output); } } if (chrr=='w') { if(k<=3) { output=119+k; fprintf( f_out, "%c", output); } else { output=93+k; fprintf( f_out, "%c", output); } } if (chrr=='v') { if(k<=4) { output=118+k; fprintf( f_out, "%c", output); } else { output=92+k; fprintf( f_out, "%c", output); } } if (chrr=='u') { if(k<=5) { output=117+k; fprintf( f_out, "%c", output); } else { output=91+k; fprintf( f_out, "%c", output); } } if (chrr=='t') { if(k<=6) { output=116+k; fprintf( f_out, "%c", output); } else { output=90+k; fprintf( f_out, "%c", output); } } if (chrr=='s') { if(k<=7) { output=115+k; fprintf( f_out, "%c", output); } else { output=89+k; fprintf( f_out, "%c", output); } } if (chrr=='r') { if(k<=8) { output=114+k; fprintf( f_out, "%c", output); } else { output=88+k; fprintf( f_out, "%c", output); } } else { while((chrr>='a') && (chrr<='q')) { output=(chrr+k); fprintf( f_out, "%c", output); printf("%c", output); break; } } } else if (chrr>='A' && chrr<='Z') { if (chrr=='Z') { if(k==0){ output=90; fprintf( f_out, "%c", output); } else { output=64+k; fprintf( f_out,"%c", output); } } if (chrr=='Y') { if(k==0 || k==1) { output=89+k; fprintf( f_out, "%c", output); } else { output=63+k; fprintf( f_out, "%c", output); } } if (chrr=='X') { if(k>=0 && k<=2) { output=88+k; fprintf( f_out, "%c", output); } else { output=62+k; fprintf( f_out, "%c", output); } } if (chrr=='W') { if(k<=3) { output=87+k; fprintf( f_out, "%c", output); } else { output=61+k; fprintf( f_out, "%c", output); } } if (chrr=='V') { if(k<=4) { output=86+k; fprintf( f_out, "%c", output); } else { output=60+k; fprintf( f_out, "%c", output); } } if (chrr=='U') { if(k<=5) { output=85+k; fprintf( f_out, "%c", output); } else { output=59+k; fprintf( f_out, "%c", output); } } if (chrr=='T') { if(k<=6) { output=84+k; fprintf( f_out, "%c", output); } else { output=58+k; fprintf( f_out, "%c", output); } } if (chrr=='S') { if(k<=7) { output=83+k; fprintf( f_out, "%c", output); } else { output=57+k; fprintf( f_out, "%c", output); } } if (chrr=='R') { if(k<=8) { output=82+k; fprintf( f_out, "%c", output); } else { output=56+k; fprintf( f_out, "%c", output); } } else if (chrr>='A' && chrr<='Q') { output=(chrr+k); fprintf( f_out, "%c", output); printf("%c", output); } } else { output=chrr; fprintf( f_out, "%c", output); printf("%c", output); break; } } fclose(f_in); fclose(f_out); } /* else { printf("The integer is not from 0 to 9"); break; } */ }

Now for some reason it's reading the scanf value but it doesn't write anything. It appears to go into the if/else loops but nothing happens.

*EDIT* ok i put in the fscanf()'s inside the loop and changed their condition, now all my program is doing is printing d to the screen.
*EDIT* It looks like it's encryping the first character in the loop then it's not stopping, perhaps it needs breaks?

Well there's only one call to fscanf, and it isn't in your loop.

6kaine9, here's some constructive criticism.

Notice the pattens in your code:

Code:

#include <stdio.h> FILE *f_in, *f_out; int var, k, chrr, status; char output; main() { printf("Enter a value from 0 to 9.\n"); scanf("%d", &k); if (k>=0 && k<=9) { f_in = fopen("message.txt", "r"); f_out = fopen("encrypted.txt", "w"); status = fscanf (f_in, "%c", &var); //chrr = (int) input while (status != EOF) { if ((chrr>=48) && (chrr<=57)) { if (chrr==57) { output=k; fprintf( f_out, "%c", output); printf("%c", output); } if (chrr==56) { output=k-1; fprintf( f_out, "%c", output); printf("%c", output); } if (chrr==55) { output=k-2; fprintf( f_out, "%c", output); printf("%c", output); } else { while((chrr>=48) && (chrr<=54)) { output=(chrr+k); fprintf( f_out, "%c", output); printf("%c", output); } } } else if ((chrr>='a') && (chrr<='z')) { if (chrr=='z') { output=99; fprintf( f_out, "%c", output); printf("%c", output); } if (chrr=='y') { output=98; fprintf( f_out, "%c", output); printf("%c", output); } if (chrr=='x') { output=97; fprintf( f_out, "%c", output); printf("%c", output); } else { while((chrr>='a') && (chrr<='w')) { output=(chrr+k); fprintf( f_out, "%c", output); printf("%c", output); } } } else if (chrr>='A' && chrr<='Z') { if (chrr=='Z') { output=67; fprintf( f_out, "%c", output); printf("%c", output); } else if (chrr=='Y') { output=66; fprintf( f_out, "%c", output); printf("%c", output); } else if (chrr=='X') { output=66; fprintf( f_out, "%c", output); printf("%c", output); } else { while((chrr>='A') && (chrr<='Z')) { output=(chrr+k); fprintf( f_out, "%c", output); printf("%c", output); } } } else { output=chrr; fprintf( f_out, "%c", output); printf("%c", output); } fclose(f_in); fclose(f_out); } } /* else { printf("The integer is not from 0 to 9"); } */ }

This is not what programming is all about. When you see patterns like these repeating themselves in your code, stop, then think about how you can structure your code to remove all this redundant code, and then fix it. This process I describe is called refactoring. It makes your programs easier to read and easier to debug.

The printf function is just so I can see what it's writing to the file on the screen. As for the fprintf() I honestly don't know how to shorten that more than it already is.

I would've loved to use just one loop for all the fprintf()'s but I honestly don't know how to make the ASCII numbers jump from like Z and go back up to A without specifically stating a condition for each one.

Check to see if this actually works:

Code:

f_in = fopen("message.txt", "r");

Have you learned about the switch/case construct yet?

I have used about the switch/case construct it's just that the assignment specifically calls for a user-defined value k to cycle the numbers, upper case letters, and lower case letters so I don't think the switch/case construct would work.

Better yet, have you learned about isupper, islower, and isdigit?

Also note that if you shift over the line (i.e., past 'Z' or 'z' or '9') then going backwards by 26 (for the letters) or 10 (for the numbers) will get you back where you need to be.

We have not read about the isupper, islower, and isdigit.

That would be a different way of doing it sure but I'd still have to write the code.

I can't exactly start from scratch this is due Tuesday at midnight and your suggestions, while great and constructive still doesn't answer my question as to why my code isn't working.

Since you appear to close your input and output files after writing one character, what else do you expect? (I say appear because you I don't care enough to fix your indentation, but I think I counted the curly braces correctly.)

Thanks again to everyone for their help.

Tabstop: You are correct the fclose is in the wrong spot, I moved it and it is now writing as it should, although there are some logical errors with my program still.

I'm still having an issues with spaces, is the space not considered a character? My spaces are not transfering over. Do I need to have another special case for it?

That last else clause should take care of spaces. Granted, the code you have posted skips every other character, but hey.

Yeah the space isn't working. Maybe I have a stray bracket somewhere?

What do you mean it skips every other character?

Well, I'm looking at the code in the first post right now, 'cause I don't see anything more recent, and you read one character into var (which gets virtually thrown away, since we don't do anything with it) and one character into chrr.

Ok I've managed to make it work through sweat and tears and pure determination I've written a total of 27 if/if else's.

Now I still can't get the numbers and spaces to work, any ideas?

I updated the code FYI.

For the numbers, setting output to 7 does not mean you will display '7', since 7 is <beep>.

the var simply tells it when to stop

it scans twice once to keep the loop going, the other for the program

ok so what do I do about the numbers? I tried to use fscan for variables for the digits 0-9 and got a segmentation fault

how do i scan single digits?

Quote:

Originally Posted by 6kaine9

the var simply tells it when to stop

it scans twice once to keep the loop going, the other for the program

You may have deluded yourself into thinking so, but that's simply not true. Print out chrr and var before you start encrypting and see for yourself.

Quote:

Originally Posted by 6kaine9

ok so what do I do about the numbers? I tried to use fscan for variables for the digits 0-9 and got a segmentation fault

how do i scan single digits?

Edit: You had that right the first time. Now you've got the logic right, you just have to not use this var thing.

But I've already used the program for encrypting. It *IS* working its just that the spacebars and numbers don't work.

If you won't print out var, I will:

Code:

var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 0 var is: 102378

where oh where could your numbers have gone. (Note this is also where your spaces have gone.)

lmao ok you're right I just printed it too.

I bow down to your greatness.

So now what, toss it?

You need to do the same reading in the loop that you did outside, or used to:

Code:

var = fscanf("%c", &chrr);

Remember fscanf returns EOF on trying to read end of file. And also that read has to be inside the while loop, as in

Code:

while ((var = fscanf("%c",&chrr)) != EOF)

And actually you don't really need var:

Code:

while (fscanf("%c", &chrr) != EOF)

ok i replaced that bit of code now it's telling me

Quote:

encrypt10.c:27: warning: passing arg 1 of `fscanf' from incompatible pointer type

Oops, forgot the filename. You'll need f_in as the first parameter.

abcdef uvwxyz ZYXWVUTS RQPONML 102378

ok this bit is what it's supposed to read

I run it and input 0 as k, and it outputs:

Quote:

abcde

It's stopping at the spacebar, why?

lmao I had a break after the "else" bit of code.

Thanks so much man you don't believe how much of a help you were.

Now to decrypt the code....lmao