Category: Coding

I’ve been coding in coding in various languages since around 1983 and this is the first time I’ve had an occasion to use a do } { while loop.

Here’s the scenario. I have four different kinds of pictures: locomotives, boxcars, tankers, and cabooses. I have eleven versions of each, one for each of eleven colors. I want to display two items on the screen at the same time and ask the child to identify the color. Now if a red boxcar and a red caboose show up on the screen at the same time, both are correct so the child can’t choose the red one. So what I want to do is check to see if the colors are the same and then pick a different object if they are.

I’ve already picked my first object from the list and this is the code I use to pick the second. I always need to pick a second item, so the do { } while construction is perfect. It runs through the code and after the first pass evaluates the conditional. In this case, it checks to see if the color of the first object (leftItem) is the same as the color of the second object (rightItem). If they are equal, it does another iteration and picks another object. I have eleven colors so the loop repeats about 9% of the time, so it doesn’t have any impact on execution. If you only had two or three colors, you’d probably want to use a different method.

Note: The code is Objective C and I changed it a bit from the original to make the loop portion clearer.

  NSInteger randomWord2;
        do {
            // Get another random number between 0 and n-1 
            //and add it to the original number plus 1
            int randomNumber2 = (arc4random() % numItems);
            // If randomNumber2 is not zero then the two words will be different
            if (randomNumber2   == 0) randomNumber2 = self.scoreKeeper.currentScreen + 1;
            randomItem2 = (randomNumber2 + self.scoreKeeper.currentScreen) % numItems;
            self.rightItem = [self.wordList getWord:randomItem2];
        // If the two objects have the same color, look for another rightItem
        } while ( [self.rightItem.color isEqual:self.leftItem.color] );

This is some code I used to put a reset button on the screen. It’s mostly self-documenting. First, create a rect. I’ve already defined the x and y coordinates—buttonX and distanceFromTop based on the screen width and other buttons on the screen. Likewise, I’ve already defined the width. The rest of the code is just assigning properties to the button. The action is a method in the file that changes the image to a ‘Selected’ image.

// Reset Button
    @synthesize resetButton = resetButton;
    ....

    CGRect resetButtonFrame = CGRectMake(buttonX, distanceFromTop,
                                         button_width, 25.0f);            
    self.resetButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.resetButton.titleLabel.font            = [UIFont systemFontOfSize: 16];
    self.resetButton.titleLabel.textColor       = [UIColor blueColor];
    self.resetButton.titleLabel.shadowOffset    = CGSizeMake (1.0, 0.0);
    [self.resetButton setTitle:@"Reset Scoring" forState:UIControlStateNormal];
    [self.resetButton setFrame:resetButtonFrame];
    [self.resetButton addTarget:self 
                             action:@selector(resetScorekeeper:) 
                   forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:self.resetButton];
    // This line makes the icons stay in the center of the screen when you rotate
    self.resetButton.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;
    
    ....

- (IBAction)resetScorekeeper:(UIButton *)sender {
    
    [self resetResultsFile];
    [sender setImage:[UIImage imageNamed:@"ResetScoringSelected.png"] forState:UIControlStateNormal];
}

Use this code:

<div class="centered"><img class="centered" src="/images/696866-spock.jpg" alt="E6-B" /><p class="caption">Let’s check that wind correction angle.</p>
</div>

Note that the whole thing is wrapped in a div and the caption is in a paragraph.

The CSS for the classes is:

Image centering in a paragraph with padding.

img.centered {
  display: block;
  margin-left: auto;
  margin-right: auto;
}

Caption

.caption {
  text-align: center;
  margin-top: -4px;
  font-style: italic;
  font-size: 80%;
}

I recently started getting lots of error statements in my error logs for a site I manage. And by lots I mean thousands each week. Since the site works fine and I haven’t changed anything recently I was puzzled as to why the were happening.

So I expanded the MySql error codes to give me more information on what file was the problem and what the MySql statement was that failed. i.e filename, query, and error message.

if (!$result) {
    error_log("product.php");
    error_log($query);
    error_log(mysqli_error($dbLF));
    die();
  }

This is a common error.

[18-Jun-2012 05:34:52 UTC] SELECT * FROM product_table
           WHERE productNum = \\\'1
           ORDER BY display_seq, name
[18-Jun-2012 05:34:52 UTC] You have an error in your SQL syntax; 

And they get more complicated:

SELECT * FROM product_table
           WHERE productNum = 38/product.php?id=381\\\'
           ORDER BY display_seq, name
[19-Jun-2012 07:47:01 UTC] You have an error in your SQL syntax;

I went though all my code and I can’t find anywhere that I could possible have such a malformed query.

What clinched it for me are these queries:

WHERE product_id = 999999.9/**//*!30000union/**/all/**/select/**/(select/**/concat(0x7e,0x27,group_concat(column_name),0x27,0x7e)/**/from/**/`information_schema`.columns/**/where/**/table_schema=0x52656D696E64657273/**/and/**/table_name=0x7573657273),0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536*/--
         WHERE product_id = 999999.9/**//*!30000union/**/all/**/select/**/(select/**/concat(0x7e,0x27,count(column_name),0x27,0x7e)/**/from/**/`information_schema`.columns/**/where/**/table_schema=0x446F776E6C6F616473/**/and/**/table_name=0x507572636861736573),0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536*/--
         WHERE product_id = 999999.9/**//*!30000union/**/all/**/select/**/(select/**/concat(0x7e,0x27,group_concat(column_name),0x27,0x7e)/**/from/**/`information_schema`.columns/**/where/**/table_schema=0x446F776E6C6F616473/**/and/**/table_name=0x507572636861736573),0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536,0x31303235343830303536*/--

There’s absolutely no way I miscoded my query to get that garbage.

Since all my product numbers are integers, I changed the code to only run if the productNum is an integer. Seems to work.

if ( isset($_GET['num']) ) { $productNum  = mysql_real_escape_string($_GET['num']); }  else { $productNum  = '';} 

// Attempts have been made to exploit the database with long strings. 
// This stops it without filling up the error log.
if ( !is_numeric($productNum) ) $productNum = '1';

The Twenty Eleven Theme is a simple theme that works well for one of the sites I manage. Unfortunately, it is broken on iPads. The navigation on the right-hand side is all the way on the bottom. There is an easy fix.

Open the file /wp=content/themes/twentyeleven/header.php

A few lines down, the header block starts. Comment out (or delete) the line <meta name="viewport" content="width=device-width" /> and you are good to go. The code snippet below shows how I did it.

<head>
<meta charset="<?php bloginfo( 'charset' ); ?>" />
<!-- Comment out this line to have it work the same on iPads
<meta name="viewport" content="width=device-width" />-->

Note: In HTML a comment starts with <!-- and ends with --> so I’ve basically added a text comment and continued it to the next line that contains the offending code.