UNIX for Dummies Questions & Answers

I know there is lseek() function that will allow to write or read from certain position in the file. Is there similar function that will let do same but for array rather then file?

Well, arrays seem to be inside languages, where you just reach out and touch them.

Perhaps you are asking about mmap()/mmap64(), which turn the file into a memory array so you never need to seek (and flush and reload buffers) ever again and you get the use of as much RAM as you can scrounge to hold most recently used pages, even if not currently mapped? JAVA has a similar facility, FileChannel. I suppose PERL can do this, perhpas calling mmap()/mmap64() directly. Solaris reads with mmap*() and it also is used in dynamic linking, so all users of a lib file have the same memory pages. If 40 people are running vi, why have 40 different copies in different VM/RAM locations?

Head and tail with character -c arguments do seek and read in the shell.

Why do you need to seek in an array at all? Memory is random-access.

I want to keep reading input from standard input and keep
putting it in array. For example..... Users types "hi". Now i
store this in array. Then user types "hello" I put this in the
same array. Now my array looks like this "hihello". I also need to have
empy char appended every time i put new string in array

Keep an integer variable to track where to put data next.

Yes i can use sprintf which will return how many bytes storwd in array
But how would i put next string into array. Like what function can i use

Where are these arrays, in C, shell, PERL, ???

Corona is saying you can put lines, each in one cell of an array shell variable, or the like.

In ksh, if you need the length of input without linefeeds, there are operators for string length. If you want part of the string, there are operators for sub-string extraction.

Code:

$ expr substr 1234567890 3 5      
34567
$