// begin table centered with a border
print ('<table align = "center" border = 1>');
$index = 0; // initialize index
for ($i=0; $i <= $rows; $i++) {
print("<tr>"); // start row
for ($k=0; $k <= $columns; $k++) {
$index++; // increment the index value
// make sure we don’t exceed array bounds!
if ($index <= $num_items) {
tableContents( $images[$index],
$names[$index],
$item_num[$index],
$item_description[$index],
$item_price[$index],
$index);
}
else {
print("<td></td>"); // make blank cell
} // end if $index…
} // end inner for
print("</tr>"); // end row
} // end outer for…
print ("</table>"); // end table
I am creating a basic php webpage that puts items in a table, however something is wrong in my for loop and I need a little help. The arrays aren't starting at 0 it seems, my $index variable is supposed to start at 0 and then increment but its spitting out the 2nd item at the beginning instead.
Any help would be appreciated! Thank you.
You have $index++ before you select your elements, that's why it starts at 1. Move it after the end of your if-else statement.
Also, per comment below be sure that your arrays don't get out of bounds. That is, if there are n elements in your array, the last element has the index of n-1. So, you probably want $index < $num_items, as well as $k < $columns and $i < $rows.
Related
I want to print an array in spiral order. For arrays with sizes 3x3, 4x4, ...etc. my code works correctly, but for 3x5, 4x6 or 5x8 sizes the output is wrong, returning only the first iteration.
This is my simple code:
private function _spiral($rows, $cols, array $array) {
$offset = 0;
while($offset < ($rows - 1)){
for($col = $offset; $col <= $cols - 1; $col++){
print($array[$offset][$col] . ' ');
}
$offset++;
$cols--;
for($row = $offset; $row < $rows; $row++){
print($array[$row][$cols] . ' ');
}
$rows--;
for($col = $cols - 1; $col >= $offset; $col--){
print($array[$rows][$col] . ' ');
}
for($row = $rows; $row >= $offset; $row--){
print($array[$row][$offset - 1] . ' ');
}
}
}
Example with 3 rows and 4 columns:
$array = array(
array(00,01,02,03),
array(10,11,12,13),
array(20,21,22,23)
)
Expected result for this array is 0 1 2 3 13 23 22 21 20 10 11 12, but the output of my function stops after 10.
For 4 rows and 4 columns:
$array = array(
array(00,01,02,03),
array(10,11,12,13),
array(20,21,22,23),
array(30,31,32,33)
)
...it should return 0 1 2 3 13 23 33 32 31 30 20 10 11 12 22 21, and that is what my code returns.
But I want both cases to work with my code. How can I correct the code to also produce the correct output for the first, and other cases?
There are a few problems with your code:
it does not treat the four directions of traversal in the same way. You have four loops for these four directions, but in some you have <= as loop-end condition in others <, in some the condition is on something minus 1, in others not.
it has no provision for when all elements have been printed by the first or second inner loop, and thus the remaining loops will in some cases print already printed elements.
the outer loop condition does not check whether there are still columns that need traversal. It is not enough to test for such rows only.
Although you could try to fix your code, I think it is better to start from scratch, taking into account that the solution should be symmetric for all four directions. This is an important intuitive reaction to develop: spot symmetries. This will lead to less code and fewer bugs.
You want to traverse a dimension (row or column) in your array until you reach the border of the array or an element you already printed. Then you want to turn 90° to the right and repeat exactly the same logic over and over again. So if your code looks different for these different directions, something is not right.
I will share two implementations. Both will use the concept of the "current" cell, and let it move around in spiral motion.
The first solution treats going back or forward along a row with the same code, and similarly it has one piece of code for traversing a column forward or backward. So this solution has two inner loops, one for traversing along a row, and another for traversing along a column. The direction in which a row or column is traversed is kept in the $direction variable, which flips between 1 and -1 at each execution of the outer loop:
function _spiral(array $array) {
// No need to have the number of rows and columns passed as arguments:
// We can get that information from the array:
$rows = count($array);
$cols = count($array[0]);
// Set "current" cell to be outside array: it moves into it in first inner loop
$row = 0;
$col = -1;
$direction = 1; // Can be 1 for forward and -1 for backward
while ($rows > 0 and $cols > 0) {
// Print cells along one row
for ($step = 0; $step < $cols; $step++) {
$col += $direction;
print $array[$row][$col] . ' ';
}
// As we have printed a row, we have fewer rows left to print from:
$rows--;
// Print cells along one column
for ($step = 0; $step < $rows; $step++) {
$row += $direction;
print $array[$row][$col] . ' ';
}
// As we have printed a column, we have fewer columns left to print from:
$cols--;
// Now flip the direction between forward and backward
$direction = -$direction;
}
}
Note the perfect symmetry between the first inner loop and the second inner loop.
In a second solution, this use of symmetry is taken one step further, in order to replace the two inner loops with only one. For that to happen we must abandon the use of separate variables for rows and columns, and use the concept of a size related to a dimension:
function _spiral(array $array) {
// This version of the function aims to treat rows and columns in the same way,
// They are just another dimension, but all the logic is exactly the same:
// $size[] has the number of rows in $size[0] and number of columns in $size[1]
$size = Array(count($array), count($array[0]));
// $current[] has the current row in $current[0] and current column in $current[1]
$current = Array(0, -1);
// $direction[] has the current row-traversal direction in $direction[0]
// and column-traveral direction in $direction[1]
$direction = Array(1, 1);
$dimension = 0; // Which dimension to traverse along, can be 0 for row, 1 for column
while ($size[$dimension] > 0) {
// Switch dimension (row to column, column to row), to traverse along
$dimension = 1 - $dimension;
// Print one line along that dimension, in its current direction
for ($step = 0; $step < $size[$dimension]; $step++) {
$current[$dimension] += $direction[$dimension];
print $array[$current[0]][$current[1]] . ' ';
}
// As we have printed a line, we have fewer left to print from:
$size[1 - $dimension]--;
// Now flip the direction between forward and backward for this dimension:
$direction[$dimension] = -$direction[$dimension];
}
}
An extended version
Upon request more than one year later: here is a version that allows one to choose the corner to start from, and whether to do it counter-clockwise instead of clockwise. This function will not print the result, but return a 1D array, with the spiral sequence. This way you can decide yourself what to do with the result: print it, or ... whatever.
function spiral(array $array, $startRight = false, $startBottom = false,
$counterClockWise = false) {
// This version allows to select which corner to start from, and in which direction.
// $size[] has the number of rows in $size[0] and number of columns in $size[1]
$size = [count($array), count($array[0])];
// $direction[] has the current row-traversal direction in $direction[0]
// and column-traversal direction in $direction[1]
$direction = [$startBottom ? -1 : 1, $startRight ? -1 : 1];
// Which dimension to traverse along: false means row, true means column.
// Every one of the optional arguments will flip the first dimension to use:
$dimension = ($startBottom xor $startRight xor $counterClockWise);
// $current[] has the current row in $current[0] and current column in $current[1]
$current = [$startBottom * (count($array)-1), $startRight * (count($array[0])-1)];
// Go back one step, outside of the grid
$current[!$dimension] -= $direction[!$dimension];
while ($size[$dimension] > 0) {
// Switch dimension (row to column, column to row), to traverse along
$dimension = !$dimension;
// Print one line along that dimension, in its current direction
for ($step = 0; $step < $size[$dimension]; $step++) {
$current[$dimension] += $direction[$dimension];
$result[] = $array[$current[0]][$current[1]]; // store in new array
}
// As we have printed a line, we have fewer left to print from:
$size[!$dimension]--;
// Now flip the direction between forward and backward for this dimension:
$direction[$dimension] = -$direction[$dimension];
}
return $result; // Return the resulting spiral as a 1D array
}
See it run on eval.in
What I'm looking for is looking for logic that allows you to print horizontal rulers between content, except for the last content block, which you do NOT want to close with a horizontal ruler.
I have this code to loop the number from 1 to 10 and I have this if inside to check if number is stored in database.
for($i=1;$i<=10;$i++){
if($i == $class->Check($i)){
echo $i;
echo "<hr>"; // if not the last!
}
}
I want to check here if it is the last data with the if condition not the loop, so if we got from if and the loop the numbers 2,3,4,7, I want to check with another if condition if it is the last number and print something.
Notice -> the for loop numbers isn't the same it's a variable this is just an example.
What is the code for (I have this loop and when if condition is true it print something then a hr tag, but I don't want the lase print to print a hr tag so I want to check if it is the last print with if condition to stop it from printing the tag).
In your condition, you can save your output in an array, instead of displaying it immediatly, and then, you can use it later, by checking if you are at the last value :
$MyOutput = [];
for($i=1;$i<=10;$i++) {
if($i == $class->Check($i)){
$MyOutput[] = $i;
}
}
for($i = 0, $len = count($MyOutput); $i < $len; $i++)
{
echo $MyOutput[$i];
if ($i == $len - 1) // are we at the last element ?
{
// your special message for the last element
}
}
Newb question: I'm using a foreach loop to get items from an array.
I need to start looping at an offset number- (I'm using a $i variable to do this, no problem).
But when my foreach reaches the end of the array I want it to start going through the array again until it reaches the offset number.
I need to do this so I can have a user open any image in an artist's portfolio and have this image used as the first image presented in a grid of thumbnail icons , with all the other images subsequently populating the rest of the grid.
Any ideas?
Please bear in mind I'm new to PHP! :)
See below for an example of my current code...
$i=0;
$limit=50;// install this in the if conditional with the offset in it (below) to limit the number of thumbnails added to the page.
$offset=$any_arbitrary_link_dependant_integer;
foreach($portfolio_image_array as $k=>$image_obj){//$k = an integer counter, $image_obj = one of the many stored imageObject arrays.
$i++;
if ($i > $offset && $i < $limit) {// ignore all portfolio_array items below the offset number.
if ($img_obj->boolean_test_thing===true) {// OK as a way to test equivalency?
// do something
} else if ($img_obj->boolean_test_thing===false) { // Now add all the non-see_more small thumbnails:
// do something else
} else {
// error handler will go here.
}
} // end of offset conditional
}// end of add boolean_test_thing thumbnails foreach loop.
};// end of add thumbnails loop.
$i = 0;
$limit = 50;
$offset = $any_arbitrary_link_dependant_integer;
$count = count($portfolio_image_array);
foreach($portfolio_image_array as $k=>$image_obj){//$k = an integer counter, $image_obj = one of the many stored imageObject arrays.
$i++;
if ($i > $offset && $i < $limit && $i < ($count - $offset)) {// ignore all portfolio_array items below the offset number.
if ($img_obj->boolean_test_thing===true) {// OK as a way to test equivalency?
// do something
} else if ($img_obj->boolean_test_thing===false) { // Now add all the non-see_more small thumbnails:
// do something else
} else {
// error handler will go here.
}
} // end of offset conditional
}// end of add boolean_test_thing thumbnails foreach loop.
};
Only thing I added was a $count variable.
Edit: If your array starts at 0 I would suggest you put the $i++; at the end of your foreach loop.
A simple method is to use two separate numeric for loops, the first going from offset to end, and the second going from beginning to offset.
<?php
// Create an example array - ignore this line
$example = array(1,2,3,4,5,6);
$offset = 3;
// Standard loop stuff
$count = count($example);
for($i = $offset; $i < $count; $i++)
{
echo $example[$i]."<br />";
}
for($i = 0; $i < $offset; $i++)
{
echo $example[$i]."<br />";
}
?>
This is also almost certainly cheaper than doing multiple checks on every single element in the array, and it expresses exactly what you are trying to do to other programmers who look at this code - including yourself in 2 weeks time.
Edit: depending on the nature of the array, in order to use numeric keys you may first need to do $example = array_values($portfolio_image_array);.
Using Answer Question to force StackOverflow to let me post a decent length of text!
OK #Mark Walet et al, not sure how to post correctly on this forum yet but here goes. I got the issue sorted as follows:
$i=0;
$offset=$image_to_display_number;
$array_length = count($portfolio_image_array);
// FIRST HALF LOOP:
foreach($portfolio_image_array as $k=>$img_obj){// go through array from offset (chosen image) to end.
if ($i >= $offset && $i <= $array_length) {
echo write_thumbnails_fun($type_of_thumbnail, $image_path, $k, $i, $portfolio_image_array, $title, $image_original);
$t_total++;// update thumbnail total count.
}
$i++;
}// end of foreach loop 1.
$looped=true;// Just FYI.
$i=0;// Reset.
// SECOND HALF LOOP:
foreach($portfolio_image_array as $k=>$img_obj){// go through array from beginning to offset.
if ($i < $offset) {
echo write_thumbnails_fun($type_of_thumbnail, $image_path, $k, $i, $portfolio_image_array, $title, $image_original);
}
$i++;
}// end of foreach loop 2.
Thankyou so much for all the help!
:)
as #arkascha suggested use modulo operator
<?php
$example = array(1,2,3,4,5,6);
$count = count($example);
$offset = 3;
for($i = 0; $i < $count; $i++) {
$idx = ($offset + $i) % count
echo $example[$idx]."<br />";
}
?>
I have a while loop that contains an if statement. The while loop works fine but when I run the following if statement for each value passed through the while loop, and the if statement returns true, the script hangs up and I get the 30 second maximum execution time error.
I am not sure if it is creating an infinite loop or what. Can anyone spot the problem?
$size = count($_POST['itemname']);
// start a loop in order to update each record
$i = 0;
while ($i < $size) {
// define each variable
$itemname= $_POST['itemname'][$i];
$id = $_POST["id"][$i];
if(preg_match('/[A-Za-z]/',$itemname)) {
echo("has words");
} else {
//update code here
}
}
You never increment $i, that is what is hanging it up as it will always be < $size
while ($i < $size) { // changed this to >
// define each variable
$itemname= $_POST['itemname'][$i];
$id = $_POST["id"][$i];
$i++; // increment $i
You never increment $i. Try a for loop instead; they're a little more explicit.
You need to increment $i somewhere outside of the if statement.
you never change $i in the while loop
you have to increment $i for each loop or else if its true once it will always pass
add $i++ between the last 2
}
}
so it looks
}
$i++;
}
I have this PHP loop,
foreach($returnedContent as $k => $v) {
$imageName = str_replace($replaceData, "", $v['contentImageName']);
echo "<a class='contentLink' href='".base_url()."welcome/getFullContent/$v[contentId]'>";
echo "<img src='/media/uploads/".strtolower($v['categoryTitle'])."/".$imageName."_thumb.png' alt='$v[contentTitle]' />";
echo "</a>";
}
Once the lopp has finished I was hoping it would be possible to do loop to print x amount of grey boxes is this possible and if so how, basically if the first loop returns 1 item i need the second loop to print out 11 boxes, if the first one returns 9 items I need the second loop to return 3 boxes.
Make sense? Can anyone help me?
So if you want a total of 12 boxes, set a counter and decrement:
$boxes = 12;
foreach($returnedContent as $k =>$v){
// all your previous stuff
$boxes--;
}
for($i = 0; $i < $boxes; $i++){
// print your box here
}
Depending on your application you may also want to check that the number of items in $returnContent is <= $boxes. If it is greater than $boxes you won't get an error but you will get rows with more than $boxes images.
Just keep a counter and increment it for each loop iteration, then add
for (;$counter < 11; ++$counter) {
do_loop_stuff();
}
Maybe you could do something like this (assuming $returnedContent is numerically indexed):
//count to 12 so we get 12 items
for ($i=0; $i<12; $i++) {
//check if there is an entry to print
if (isset($returnedContent[$i])) {
$v = $returnedContent[$i];
$imageName = str_replace($replaceData, "", $v['contentImageName']);
echo "<a class='contentLink' href='".base_url()."welcome/getFullContent/$v[contentId]'>";
echo "<img src='/media/uploads/".strtolower($v['categoryTitle'])."/".$imageName."_thumb.png' alt='$v[contentTitle]' />";
echo "</a>";
} else {
//draw grey box
}
}
After the first loop, you can do:
for($i = 0; $i < 12 - count($returnedContent); $i++)
{
// print the grey boxes.
}
Hmmm Im not sure Im understanding you but
$c = count($returnedContent);
will get you the amount of items in the variable
then:
$c = (11-$c);
if($c > 0) {
for($i=0;$i<$c;$i++) {
// print gray box
}
}
after the first loop. You could also use a counter variable inside the first loop.
I did interpret the question as "Do something when the loop has finished iterating".
In which case a for/foreach loop isn't the best choice here.
how about
<?php
$i = 0;
do {
echo $i;
} while ($i > 0);
//then do whatever else you need to.
?>