One might note that the 1st code fragment (making the wild assumption that none of the obscured lines make any updates to the ctr variable), sets and writes three successive elements of the array a[] each time through the loop. This seems to be what you want to do, although it would probably be much more efficient to just have the loop set elements of the array and then use a single write of the entire array when the loop finishes.
The second code fragment sets elements of the array in about the same way in the first loop. But, the second loop writes elements 0, 1, and 2 of the array on the 1st pass; elements 1, 2, and 3 on the 2nd pass; 2, 3, and 4 on the 3rd pass; etc. To be logically equivalent to the first code fragment, you would need to change:
to something more like:
But, again, writing the entire array with a single write would seem to be much more efficient than writing the entire array one byte at a time.
One would expect that the file produced by the first code fragment you showed us is much smaller than the file produced by the second code fragment you showed us (by about a factor of 3). Maybe that would be a hint as to what might not be working???
Don Cragun, your suggestion did not work at first, but is working now that I not only changed the counter increment from 1 to 3, but also changed the loop stop condition from
to
I was writing the array one byte por pixel, because I was storing the contents on three different arrays (since I was not being able to do so with one), one for each color component, and in the writing phase I had to alternate between them.
Hi All,
How do I write into shared memory blocks using multiple threads? For example, I have created 50 threads to write into shared memory and 50 threads to read from shared memory.
I have already created a shared memory and I want to write into shared memory as follows:
... (0 Replies)
In a recent research experiment I was handling, I faced this task of managing huge amounts of data to the order of Terabytes and with the help of many people here, I managed to learn quite a lot of things in the whole process. I am sure that many people will keep facing these situations quite often... (2 Replies)
Hi,
I have the following variable declaration which looks like a 3d array or N matrixs KxK of floats
float (*table);
I have to pass to a function only the first table.
How can I do it??
Thanks (6 Replies)
Hi
My below code to display the contents in array is not working. Pls correct my code.
cat $file | while read file1
do
filenames=$file1
let i=$i+1
echo $i
echo ${filenames}
done
let j=1
while
do
echo "${filenames}"
let j=$j+1
done (5 Replies)
ok, so here is the issue, I have 2 arrays.
I need to be able to create a loop that will find ${ARRAY1 in the text doc, and replace it with ${ARRAY2 then write the results. I already have that working. The problem is, I need it to do that same result across however many items are in the 2... (2 Replies)
i have an array (with each element length "n") which is dynamic and has alphanumeric characters.
i want to check if any of the elements of the array are null and replace it with a string of "n" zeros for that element.
can you suggest me a code for the same. (1 Reply)
Hey guys,
I'm new to shell scripting and I'm trying to write a script that takes user input and copies the specified columns from a data file to a new one. In order to account for the possibility of a variable number of columns to copy I wrote a loop that encodes the user's choices in an array... (16 Replies)
Hello!
I wish to create a script that will automate the creation of HTML files...
for example, if my HTML starts out containing:
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>$TITLE</title>
</head>
I want to put that into something that I can read and write later on. My... (4 Replies)
I need shell script for the following specfic need, I'll get following output after running my program.
I wanted every 50th row in the coloumn and take into array.
For example input
==============
03
03
03
03
05
05
05
05
07
07
07
07
I wanted to extract 3,5,7 and store it in... (12 Replies)
while i've used arrays to work with variables, i've never used them to loop through a set of strings and wanted to ask the community for some feedback or assistance.
let me be specific. here's my code:
# URL port Variables
port2195=`nc -z $url2195 2195`
port2196=`nc -z $url2196 2196`... (5 Replies)
Discussion started by: hungryd
5 Replies
LEARN ABOUT CENTOS
foreach
foreach(n) Tcl Built-In Commands foreach(n)
__________________________________________________________________________________________________________________________________________________NAME
foreach - Iterate over all elements in one or more lists
SYNOPSIS
foreach varname list body
foreach varlist1 list1 ?varlist2 list2 ...? body
_________________________________________________________________DESCRIPTION
The foreach command implements a loop where the loop variable(s) take on values from one or more lists. In the simplest case there is one
loop variable, varname, and one list, list, that is a list of values to assign to varname. The body argument is a Tcl script. For each
element of list (in order from first to last), foreach assigns the contents of the element to varname as if the lindex command had been
used to extract the element, then calls the Tcl interpreter to execute body.
In the general case there can be more than one value list (e.g., list1 and list2), and each value list can be associated with a list of
loop variables (e.g., varlist1 and varlist2). During each iteration of the loop the variables of each varlist are assigned consecutive
values from the corresponding list. Values in each list are used in order from first to last, and each value is used exactly once. The
total number of loop iterations is large enough to use up all the values from all the value lists. If a value list does not contain enough
elements for each of its loop variables in each iteration, empty values are used for the missing elements.
The break and continue statements may be invoked inside body, with the same effect as in the for command. Foreach returns an empty string.
EXAMPLES
This loop prints every value in a list together with the square and cube of the value:
set values {1 3 5 7 2 4 6 8} ;# Odd numbers first, for fun!
puts "Value Square Cube" ;# Neat-looking header
foreach x $values { ;# Now loop and print...
puts " $x [expr {$x**2}] [expr {$x**3}]"
}
The following loop uses i and j as loop variables to iterate over pairs of elements of a single list.
set x {}
foreach {i j} {a b c d e f} {
lappend x $j $i
}
# The value of x is "b a d c f e"
# There are 3 iterations of the loop.
The next loop uses i and j to iterate over two lists in parallel.
set x {}
foreach i {a b c} j {d e f g} {
lappend x $i $j
}
# The value of x is "a d b e c f {} g"
# There are 4 iterations of the loop.
The two forms are combined in the following example.
set x {}
foreach i {a b c} {j k} {d e f g} {
lappend x $i $j $k
}
# The value of x is "a d e b f g c {} {}"
# There are 3 iterations of the loop.
SEE ALSO
for(n), while(n), break(n), continue(n)
KEYWORDS
foreach, iteration, list, looping
Tcl foreach(n)