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en:create:php [22.02.2017 10:26]
aitorme.uni-saarland [Functions]
en:create:php [06.06.2017 13:26] (current)
admin [Variables]
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 ===== Variables ===== ===== Variables =====
  
-The word //​function//​ derives from mathematics. Although the command ''​question()''​ has not much in common with functions. ​But other functions can actually compute things. For example, the command ''​[[:​en:​create:​functions:​random|random()]]'' ​computes a random ​number.  +The word //​function//​ derives from mathematics. Although the command ''​question()''​ has not much in common with functions. ​Yet, other functions can actually compute ​or determine ​things. For example, the command ''​[[:​en:​create:​functions:​casenumber|caseNumber()]]'' ​determines the number ​of the current interview case
- +
-The function ''​random()''​ expects two parameters: ​the smallest and the largest number that can be drawn. ''​random(1,​6)''​ will draw a number between 1 and 6. We can use this number, e.g. to choose a stimulus randomly.+
  
 <code php> <code php>
-$number = random(1,6);  // Draws a number between 1 and 6+$number = caseNumber();
 </​code>​ </​code>​
  
-To use the output of this function (in this case the random ​number), we need to file it somewhere. To do so, most programming languages use variables. You can write anything into a variable. But at the beginning, no one will see this.+To use the output of this function (in this case the interview ​number), we need to file it somewhere. To do so, most programming languages use variables. You can write anything into a variable. But at the beginning, no one will see this, and it will not be stored in the data set.
  
-In PHP, variables start wit a dollar-sign ($). The example above uses the variable ''​$number''​. You can name your variables whatever you like -- except for the fact, that you must not use most special signs (!"​§$%&/​()=...),​ apart from the underscore (_). You could name the variable ''​$random_number_variable'',​ too.+In PHP, variables start wit a dollar-sign (''​$''​). The example above uses the variable ''​$number''​. You can name your variables whatever you like -- except for the fact, that you must not use most special signs (!"​§$%&/​()=...),​ apart from the underscore (''​_''​). You could name the variable ''​$interview_number_variable'',​ too.
  
-The equal sign (%%=%%) is an operator. In this case it makes sure, the output of the function ​ ''​random()''​ is saved in the variable ''​$number''​ on the left. So the variable ''​$number''​ now contains ​ a random ​number.+The equal sign (%%=%%) is an operator. In this case it makes sure, the output of the function ​ ''​caseNumber()''​ is saved in the variable ''​$number''​ on the left of the operator. So the variable ''​$number''​ now contains ​the interview ​number.
  
-If we want to print the random ​number onto the screen, we need the command ''​[[:​en:​create:​functions:​html|html()]]''​. This function does nothing else than to print HTML-code (which is, basically, text) into the questionnaire.+If we want to print the interview ​number onto the screen, we need the command ''​[[:​en:​create:​functions:​html]]''​. This function does nothing else than to print HTML-code (which is, basically, text) into the questionnaire.
  
 <code php> <code php>
-$number = random(1,6);  // Draws a number between 1 and 6 and saves it into $number+$number = caseNumber();
 $text = (string)$number;​ // Converts the number into text and saves it into $text $text = (string)$number;​ // Converts the number into text and saves it into $text
-html($text); ​ // Prints the text $text, which contains the random number+html($text); ​ // Prints the text stored in $text
 </​code>​ </​code>​
  
-**Advice:** Why we need to convert the number into text: You could also write ''​html($number)''​ -- which will work. But as SoSciSurvey ​expects to output //text// with ''​html()'',​ it will be irritated, why you want to output a //number// (which is usually used for computing, not output). It will simply print an error message to advise you about the (alleged) mistake.+**Advice:** Why we need to convert the number into text: You could also write ''​html($number)''​ -- which will work. But as SoSci Survey ​expects to output //text// with ''​html()'',​ it will be irritated, why you want to output a //number// (which is usually used for computing, not output). It will simply print an error message to advise you about the (alleged) mistake.
  
-If copying the above code into a PHP-code-field on a questionnaire page, you will see an unspectacular outcome: A random ​number ​between 1 and 6. When reloading the pagea different number will be shown.+If copying the above code into a PHP code-field on a questionnaire page, you will see an unspectacular outcome: A number, ​increasing with every new interview that is started.
  
-{{:​en:​create:​scr.php.random.png?​nolink|Display of a random ​number in the questionnaire}}+{{:​en:​create:​scr.php.random.png?​nolink|Display of a number in the questionnaire}}
  
-How random numbers are of use to you, is described in the chapter [[randomization]]. For the moment, we will concentrate on variables: You can save values into them and call those values later on.+You will probably not need the function ''​caseNumber()''​ very often. For the moment, we will concentrate on variables: You can save values into them and call those values later on.
  
 ===== Concatenating strings/​texts ===== ===== Concatenating strings/​texts =====
en/create/php.txt · Last modified: 06.06.2017 13:26 by admin
 
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