I Found some Useful function
but I want to Understand it so I can do something like it

what parts of the code is confusing to you?

what parts do you already understand?

the long short is you are creating a custom shell environment where you accept user input, then send that input to be tokenised, or broken into pieces, then send the tokens to the execute function to spawn child processes based on the tokens.

shell runs
..accepts input
..sends input to parse
....parse tokenises input
..shell sends tokens to execute function
....execute runs tokens and informs of error if failure occurs

Actually we didn't understand any thing
But the important thing it's working as our teacher want


But the worst thing in the world
We have to explain it to here

first
the word PLEASE is NOT spelled as "plz"
-- the nun's will smack your knuckles with a ruler for that

also this is NOT a 140 character SMS text message
so PLEASE!!!!!!! do not use "text speak"

Ok ok I will write it " please"
I am not that much good in English language
I didn't know this is wrong to write it like this

Anyhow , what about the function above :'(

Your job is to tell the teacher how it works.

Your question to us is "How does it work?"

How do you expect us to answer you without doing your work for you?

if the teacher and textbook are of little help then the only recourse is to tinker

here is what you do...
take your code base,
compile it,
and run it with a series of different inputs

then go back to the code base and change one thing in it that you are having a hard time understanding, only one thing at a time and only slightly so that you can recognise and keep track of the changes,
then recompile and send the same series of inputs

try changing
to
how did the output change? what can you now infer about the code from seeing these changes?

if a change completely breaks the program then search for error codes online
for instance looking at this potentially confusing line:
if i change strtok to strtik, the program fails.. better investigate..
now i know somewords followed immediately by a parenthesis signals a function call, but the function is vacant from the code, so maybe it is built into the system... searching:
https://www.google.com/search?q=strtok
lands me here:
http://www.cplusplus.com/reference/cstring/strtok/
this explains clearly what strtok does, what arguments it takes and what kind of activity i should expect when i run it
do this for every bit you find confusing
move line by line

now with your new knowledge go back to the original code base and change something else,
repeat

Noooo, the problem not that much worst
Sure I know what the purpose of the code
It will print the shall comment from inside that program
The last function which there name shall
Will print it by using first two function
And I know the concept
But we not understand the parent and child and this thing in first function

what did i suggest?
search terms that are unfamiliar to you until all terms are familiar

https://www.google.com/search?q=chil...+process+linux ::
http://en.wikipedia.org/wiki/Child_process
http://www.lynuxworks.com/products/posix/fork.php3

https://www.google.com/search?q=fork ::
http://linux.die.net/man/2/fork
http://www.cplusplus.com/forum/unices/14125/

if (argv[0] != NULL && strlen(argv[0]) == 4 && strncmp(argv[0], "exit", 4) == 0)

And


char line[1024];

And


char* argv[64] = {NULL};



Thank u cin

What this line means

https://www.google.com/search?q=cplu...%5B1024%5D&rlz

https://www.google.com/search?q=cplusplus+char+line

https://www.google.com/search?q=cplusplus+char

any of these have results that helped you?

Thank u
I will try to understand from those references

Is it just me or has the original code been removed??

Actually this is function inside the code
There is no other function
But I csn not putting it complete now
Any how inshAlla I will try to understand it
Thank u all

grail, yes, the original post was edited and the code removed.. unsure why exactly