how to pass constants as part of a string in php

Question

I am trying to pass the app_id and app_key in the response string. I am setting those as constants and then passing them in the string. I am getting syntax error

Parse error: syntax error, unexpected ':'

What am i doing wrong? sorry I am pretty new to PHP

    $app_id = 123456; 
    $app_key = '1234abcd5678';

    $query_string = https://apiresponse.htm?app_id=$app_id&app_key=$app_key;

    echo $query_string;

Strings have to be delimited by `'` or `"`. http://www.php.net/manual/en/language.types.string.php. How else would PHP know that `http://...` is supposed to be a string? — Felix Kling, Feb 24 '14 at 00:55
Those are just variables, they're not constants. Also, you need to put quotes around your URL string. — Jonathon Reinhart, Feb 24 '14 at 00:55

score 3 · Answer 1 · answered Feb 24 '14 at 00:55

3

You need to surround with quotes your string and concatenate your variables to avoid the error

$query_string = 'https://apiresponse.htm?app_id='.$app_id.'&app_key='.$app_key;

answered Feb 24 '14 at 00:55

Fabio

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Or he could use double quotes and not use string concatenation. – Felix Kling Feb 24 '14 at 00:56
Yeah he might do that as well – Fabio Feb 24 '14 at 00:57

score 2 · Answer 2 · edited May 23 '17 at 12:10

... But $app_id and $app_key are not constants, they are usual scalar variables (!). So to express your $query_string the best thing is

$query_string = "https://apiresponse.htm?app_id=$app_id&app_key=$app_key";

more fast and readable than concatenation.

Use define() to express constants:

  define('app_id','123456');
  define('app_key','1234abcd5678');
  $query_string = 'https://apiresponse.htm?app_id='.app_id.'&app_key='.app_key;

PS: now the best way the concatenation operator, like the @Fabio's suggestion.

score 1 · Answer 3 · answered Feb 24 '14 at 00:57

1

Use " for replace vars to values in string

$query_string = "https://apiresponse.htm?app_id=$app_id&app_key=$app_key";

It is cleaner than string concat (like 'a='.$a)

answered Feb 24 '14 at 00:57

Max

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score 1 · Accepted Answer · answered Feb 24 '14 at 01:00

Your $query_string is not enclosed by single- or doublequotes.

In this case, as your string contains variables you should use doublequotes. That way, you don't have to break out of the string to add the variables.

$query_string = "https://apiresponse.htm?app_id=$app_id&app_key=$app_key";

If you were to use singlequotes, you would have do this:

$query_string = 'https://apiresponse.htm?app_id='.$app_id.'&app_key='.$app_key;

how to pass constants as part of a string in php

4 Answers4