Just don't do that! Advanced users: Learn about the magic method _toString(). Quotation marks are not necessary or appropriate with other variable types, such as arrays, objects, integers, etc. Quotation Marks Used With Other Variable Types PHP knows what end-of-line sequence is appropriate for the OS and working environment.) (But there is a better way of inserting end-of-line characters: use the predefined and context aware constant, PHP_EOL instead. For example, you can embed tab characters by using \t and you can insert Unix end-of-line characters by using \n. When a string is enclosed in double-quotes PHP will interpret escape sequences for certain special characters that are prefixed by the backslash. THIS LINE MISUSES SINGLE QUOTES $sql = 'SELECT id FROM myTable WHERE name='Ray' LIMIT 1' // OUTPUTS: Parse error: syntax error, unexpected 'Ray' (T_STRING) in /path/to/script.php on line 2ĭouble Quotes Provide More Than Just Variable Substitution The PHP parser expects the single quoted string that starts with SELECT to end at the equal sign, but it finds extraneous data after the matching single quote. When quotes are misapplied, PHP will throw a parse error.
The second assigns a single quote (apostrophe). The first assigns a double quote to the $x variable. Both of these statements are syntactically correct. Quotes can become part of a variable if you assign them correctly. $nom = 'Ray' $sql = "SELECT id FROM myTable WHERE name='$nom' LIMIT 1" See also When Quotes or Apostrophes are Part of the Data, below. You use the double quotes for the outermost wrapper and single quotes around the variables that are injected into the query. PHP allows you to mix quotes and apostrophes in certain data structures, one of the most useful being the SQL query string. You can also use string concatenation, like this: $x = 'Alphabet Soup' $y = '$x for lunch' $x = 'Alphabet Soup' $y = "$x for lunch" īut what if we had used single quotes? In the example below $y variable would contain " $x for lunch." When single quotes are used, no variable substitution is performed. After this has been executed, the contents of $y is "Alphabet Soup for lunch." When you want an assignment statement to mix literal strings with PHP variables, you must use double quotes. This is the preferred way to write the expression avoid unnecessary quotes. Since there is no mix of literal string values and variable values, PHP will also allow you to write this without any quotes. First, Alphabet Soup is assigned to $x, then $x is assigned to $y.
PHP DOUBLE QUOTES DATABASE CODE
This code example is functionally identical to the immediate prior example. Double quotes allow variable substitution single quotes do not. When you use variables (as opposed to literal strings) in PHP, there are different meanings for single and double quotes. $x = 'Alphabet Soup' $y = "Alphabet Soup" Note that one uses single quotes and the other uses double quotes. If you want to assign these literal string values to PHP variables, you must put quotes around them in the assignment statement. You can probably figure out the lengths of the other two strings. The first string is the single capital letter "A" and it has a length of one character. The code snippet below has examples of perfectly valid strings. We will show some examples and explanation below.Ī string is nothing more than a few characters strung together. If it doesn't all "click" at first, don't be too concerned. You need to understand the terms "variable" and "string" as they are used in the context of computer programming. And it got me thinking, "How can we explain the rules for quotation marks?" For better or worse, PHP has so many rules! This article tries to answer the questions.įirst, some mandatory reading. This question seems to come up a lot for developers who are new to PHP.
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