As written without quotes, PHP should raise a Notice." and I had no code after the heredoc code.foo1code gives "syntax error, unexpected $end".But in foo2and foo3.php, when you add a php close tag or when you have some more code after heredoc it works fine. Let’s now look at the four different ways of creating strings.
The example below illustrates how the Heredoc method is used to create string values. Note: you can use anything you like in place of EOT Output: The Nowdoc string creation method is similar to the heredoc method but works like the way single quotes work. Nowdoc is ideal when working with raw data that do not need to be parsed.This is a very common operation in development, and changing a string value requires to recompute the hash value as well.Forgetting such a step will lead to bugs that could cost some time to track. You could need such a concept in extension development. It adds memory management facilities, so that a same string can be shared in several places without the need to duplicate it.Also, some strings are “interned”, that is they are “persistent” allocated and specially managed by the memory manager so that they don’t get destroyed across several requests.Variable values can change over the course of a script.Here're some important things to know about variables: In the above example we have created two variables where first one has assigned with a string value and the second has assigned with a number.If you don’t do it yourself, on a debug build, the engine will shout at you about a memory leak you just created. The “releasing” is a simple operation : decrement the reference counter of the string, if it falls to zero, the API will free the string for you.If you pass 1, you ask for what we called a “persistent” allocation, that is the engine will use a traditional C . If you forget to release a string, you will very likely create a memory leak. That is what we do : we change the final ‘r’ in ‘bar’ with a ‘z’, for ‘baz’.Let’s look at an example that creates a simple string in PHP.The double quotes are used to create relatively complex strings compared to single quotes.