php substr() expects parameter 1 to be string, array given

Question

Hi i am trying to get the List of columns from a specific table in mysql and then generate a form based on the columns but i keep getting an error and the page is just blank.

mysql_select_db($DB_Name) or die(mysql_error());
$query=mysql_query("SHOW COLUMNS FROM mytable") or die (mysql_error());
$j=0;

while($row=mysql_fetch_assoc($query)){
    if(substr($row,0,2)=="S_"){
        echo substr($row,2);?>:<input type="text" name="<?php echo $row;?>" maxlength="<?php echo getlength($j, "mytable");?>" /><?php ?><!--textbox code here --><?php
    }
    $j++;
}

getlength(); is a method i wrote to make it easier to get the length of a field for a column. It works accurately.

thanks

i think i didnt mention. Since the site is dynamic the name of the column isnt known. The point of this is to get the list of column names from a specific table and display it in an orderly manner.

using substr you can restrict the count of string values,not an array... — Mohammed Nagoor
– Mohammed Nagoor, Commented Sep 10, 2012 at 5:19
Who keeps decreasing my reputation? I did my research first and tried to be clear. — Error Messages
– Error Messages, Commented Sep 10, 2012 at 7:17

Ares · Accepted Answer · 2012-09-10 05:17:28Z

2

mysql_fetch_assoc returns an associative array. In this case you very likely are getting an array what kind of looks like this:

[FIELD] => "Name of the field",
 [Type] => "varchar(32)",
 [Null] => YES,
 [Key] => PRI,
 [Default] => '',
 [Extra] => ''

So, if you want to check the field name for S_ then you need to change your substr line to

substr($row['FIELD'], 0, 2)

answered Sep 10, 2012 at 5:17

Ares

5,9033 gold badges37 silver badges51 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Mohammed Nagoor · Accepted Answer · 2012-09-10 05:19:15Z

2

When you call substr(), you're currently passing in $row, which is an array. You need to specify an index in the $row in order to return a particular element like this:

 $row['name']

edited Sep 10, 2012 at 5:19

Mohammed Nagoor

8842 gold badges12 silver badges25 bronze badges

answered Sep 10, 2012 at 5:01

techie_28

2,1454 gold badges44 silver badges65 bronze badges

Comments

devrez · Accepted Answer · 2012-09-10 05:30:07Z

1

You need to identify the column you wanted to trace. Here is the correct script below:

<?php
    if(substr($row['some_column'],0,2)=="S_"){
        echo substr($row['some_column'],2);

    }
?>

Hope that this help you.

answered Sep 10, 2012 at 5:30

devrez

1034 silver badges12 bronze badges

1 Comment

Error Messages Over a year ago

not possible, the column will be added/removed/changed sometimes. The form generated is dynamic that means whichever column is in the table is used as a basis to generate the form and also for validating user input.

Vinay · Accepted Answer · 2012-09-10 07:17:16Z

0

Replace

if(substr($row,0,2)=="S_"){
    echo substr($row,2);?>

with

 if(substr($row['FIELD'],0,2)=="S_"){
    echo substr($row['FIELD'],2);?>

edited Sep 10, 2012 at 7:17

answered Sep 10, 2012 at 5:19

Vinay

2,5944 gold badges27 silver badges35 bronze badges

1 Comment

Error Messages Over a year ago

i get undefined index instead

Collectives™ on Stack Overflow

php substr() expects parameter 1 to be string, array given

4 Answers 4

Comments

Comments

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related