Thread: Urgent C program help plz

Please show some work!!

Read this link Announcements - General Programming Boards

Tim S.

If that's your assignment, and it's urgent, and it's that urgent over Christmas, and you have not a line of code - honestly, just give up the course now. Seriously.

What you are discussing is, what? A couple of hundred lines of code at best? To get a single-process version running will be a few dozen lines, if that. The rest is just applying "what you learned in the last tutorial", if standard educational procedures are anything to go by.

What do you have? If you honestly have nothing but take the time to register and copy/paste this to several sites, you could have had a working version enough that we could help in the same time.

I suggest you do your homework. Failing that, I suggest you drop or change your course. Because if this stumps you so much that you're posting for help on multiple sites so soon after Christmas with no idea how to proceed - well, you aren't going to get much further without a lot of work on your end anyway.

Yeah, we're like doctors. We ALWAYS believe when the patient has a "friend" with a problem, especially if it's embarrassing...

dear doctors my problem is that I am not understanding the question not more ! what I am realizing is that I have to fork 4 processes and each one must be read into a buffer

"which then writes it into the code and then specify which is the P and K "

this quoted thing I am not finding out the way to do it ! I want to add that I know nothing about C programming language and those which I realized is what I have read !

Code:

.#include<stdio.h>
 #include<sys/types.h>
 #include<unistd.h>
 typedef struct decrypt
 {
 int p;
 int k;
int c;
c=p^k;
 }decrypt;
 int main()
 {
 decrypt s[10];
 int n,fd,i;
 fd=open("p.c",O_CREAT,777);//creates a new file
 if(fd<0)
 {
 printf("\nFailed to create file\n\n");exit(-1) 
 }
 fd=open("p.c",O_RDWR,777)//open the file for read and write
 printf("Enter the number to decrypt:");
 scanf("%d",&n);
 printf("Enter the key\n");
 for(i=0;i<n;i++0
 { 
 
 scanf("%d",&s[i].p);
 
 scanff("%d",&s[i].n);
 write( fd,s[i],sizeof(s) );//write to the file which the file discriptor is pointing to
 }
 
return 0;//return success to kernel
 }
//didn't know if I wrote it properly or even how to use semaphores  please someone help me in here

.

Originally Posted by tigerfady11

dear readers I have done my researches and still un-able to solve this program so please I need someone to help me or even solve it but as I think we must use semaphores, forks and pipes that's what I think but not understanding how to start am not good in C language... thanks for all.

We are requested to implement a code cracking system. The system will deploy four processes (p1,p2,p3 & p4) to try to guess the password of an encrypted code.
For encryption, we consider that the formula is: C = P XOR K, where
• C = encrypted code
• P = plain text
• K = key
For decryption the formula is: P = C XOR K. So, your program will try to find K using this formula. The XOR operator is ^.
Given an encrypted code C and plain code P your program should deploy three processes to try and find the key used to encrypt the plain code. These three processes will be under the control of process P1.
All processes will send their results to process P1 and process P1 will terminate the three processes and display the encryption key and decrypted text once any of the three processes finds the key.
For simplicity we will consider that we have the original number P stored in a file called plain.txt and the encrypted code is stored in a file called cipher.txt. Consider that only numbers are stored in these files and they have a range between 0 and 100000000.
So we have P and C your program should find the key K. Consider that K is a positive number between 0 and 1000000.

I can't help but wonder if this user isn't in the same place where all the outsourcing is going, threatening real programmers jobs.

Sorry, but for someone posting such a random gibberish that barely looks like code, we cannot help you to "urgently" solve a problem such as this; which in all reality is going to take weeks to learn how to do, minimum. You've probably waited until way past when someone would have been able to help you!

Don't worry, failing isn't a total loss, as long as you learn from it.

That code would never compile in its current state, and thus you've obviously never tried to compile it.

Assignments inside struct definitions, stray characters, double-opening the same file immediately, functions that don't exist (scanff?).

It's a bad copy/paste/guess how things might be with no testing or context or even basic C knowledge. And it also does precisely zero of what is asked of you (there is no "encryption" at all, unless you think that single invalid assignment inside the struct defition counts).

I'm guessing that you're just THAT far behind that you have no idea what you're supposed to be doing, not having followed previous tutorials at all, not just one or two.

Seriously, get it to the point where you can compile it, and we'll then help a little. Then you'll need to get it to the point where it *works* in some fashion (which is a totally different thing), and we'll then help a little more. Then you need to get a program that encrypts as specified, then we'll help a little more. Then you'll be CLOSE to getting an answer.

At this rate, it's taken you - what - 24 hours to copy/paste some junk that doesn't even compile and contains absolute nonsense. It's going to take a LOT longer for you to get close to having something worthy of handing in. Depending on your schedule, I suggest you knuckle down and learn some C, or give up entirely.