PHP - concatenate or directly insert variables in string

Question

I am wondering  What is the proper way for inserting PHP variables into a string   This way   echo  Welcome    name       Or this way   echo  Welcome  name     Both of these methods work in my PHP v5 3 5  The latter is shorter and simpler but I m not sure if the first is better formatting or accepted as more proper

User · Answer

I use a dot    to concate string and variable  like this- echo  quot Hello  quot   var   Sometimes  I use curly braces to concate string and variable that looks like this- echo  quot Hello   var  quot

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I know this question already has a chosen answer  but I found this article that evidently shows that string interpolation works faster than concatenation  It might be helpful for those who are still in doubt

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Double-quoted strings are more elegant because you don t have to break up your string every time you need to insert a variable  like you must do with single-quoted strings    However  if you need to insert the return value of a function  this cannot be inserted into a double-quoted string--even if you surround it with braces     syntax error      s    Hello  trim  world        the only option  s    Hello     trim  world

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I know this is an old question  but I think someone has to mention all pros  amp  cons   Better Syntax  That s personal preference   Performance  No difference  As many mentioned  double-quote might be faster if using unrealistically many variables   Better Usage  Single quote  mostly   As  Khez said  with single quote you can concatenate anything  even function calls and variable modification  like so  echo  hi     trim  name      i   1    The only thing double-quote can do that single-quote cannot do is usage of  n   r   t and alike   Readability  No difference  may personal preference apply    Writability Re-Writability Debugging  In 1-line statements there is no difference  but when dealing with multiple lines  it s easier to comment uncomment lines while debugging or writing  For example    q    SELECT           t1 col1            t2 col2            t3 col3           FROM tbl1 AS t1           LEFT JOIN tbl2 AS t2 ON t2 col2   t1 col1           LEFT JOIN tbl3 AS t3 ON t3 col3   t2 col2           WHERE t1 col1        x                 AND t2 col2        y                 AND t3 col3        z               ORDER BY t1 col1 ASC           LIMIT 10     Less Escaping  Single-quote  For single quote you need to escape 2 characters only    and     For double quote you need to escape 2 characters        and 3 more if required       and      Less Changes  Single quote  For example if you have the following code   echo  Number      i          And you need to increment 1 to  i  so it becomes likes   echo  Number       i   1           But for double quote  you will need to change this   echo  Number  i      to this   echo  Number       i   1             Conclusion  Use what you prefer

User · Answer

Between those two syntaxes  you should really choose the one you prefer  -   Personally  I would go with your second solution in such a case  Variable interpolation   which I find easier to both write and read   The result will be the same  and even if there are performance implications  those won t matter 1    As a sidenote  so my answer is a bit more complete  the day you ll want to do something like this   echo  Welcome  names      PHP will interpret your code as if you were trying to use the  names variable -- which doesn t exist  - note that it will only work if you use    not    for your string   That day  you ll need to use       echo  Welcome   name s     No need to fallback to concatenations    Also note that your first syntax   echo  Welcome    name        Could probably be optimized  avoiding concatenations  using   echo  Welcome     name          But  as I said earlier  this doesn t matter much       1 - Unless you are doing hundreds of thousands of concatenations vs interpolations -- and it s probably not quite the case

User · Answer

Either one is fine  Use the one that has better visibility for you  And speaking of visibility you can also check out printf

User · Answer

You Should choose the first one  They have no difference except the performance the first one will be the fast in the comparison of second one   If the variable inside the double quote PHP take time to parse variable   Check out this Single quotes or double quotes for variable concatenation   This is another example Is there a performance benefit single quote vs double quote in php   I did not understand why this answer in above link get upvoted and why this answer got downvote   As I said same thing   You can look at here as well  What is faster in PHP  single or double quotes

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From the point of view of making thinks simple  readable  consistent and easy to understand  since performance doesn t matter here     Using embedded vars in double quotes can lead to complex and confusing situations when you want to embed object properties  multidimentional arrays etc  That is  generally when reading embedded vars  you cannot be instantly 100  sure of the final behavior of what you are reading  You frequently need add crutches such as    and    which IMO adds confusion and makes concatenation readability nearly equivalent  if not better  As soon as you need to wrap a function call around the var  for example htmlspecialchars  var   you have to switch to concatenation  AFAIK  you cannot embed constants    In some specific cases   double quotes with vars embedding  can be useful  but generally speaking  I would go for concatenation  using single or double quotes when convenient

User · Answer

It only matter of taste  Use whatever you wish     Most of time I am using second one but it depends    Let me suggest you also to get yourself a good editor which will highlight a variable inside of a string

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If you want to execute a SQL command and your variables are array members  then you should not use single quotes inside    of array  like this         for example if you use this string as a SQL command  you get server error 500    con   mysqli connect  ServerName    dbUsername    dbPassword    mysqli select db  con   dbName       ID  is auto increment field   sql    INSERT INTO sampleTable  ID  TraceNo  VALUES       sampleArray  TraceNo       mysqli query  con   sql    The correct string is      ID  is auto increment field   sql    INSERT INTO sampleTable  ID  TraceNo  VALUES       sampleArray TraceNo

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Since php4 you can use a string formater    num   5   word    banana    format    can you say  d times the word  s   echo sprintf  format   num   word     Source  sprintf

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Go with the first and use single quotes    It s easier to read  meaning other programmers will know what s happening It works slightly faster  the way opcodes are created when PHP dissects your source code  it s basically gonna do that anyway  so give it a helping hand  If you also use single quotes instead of double quotes you ll boost your performance even more    The only situations when you should use double quotes  is when you need  r   n   t  The overhead is just not worth it to use it in any other case   You should also check PHP variable concatenation  phpbench com for some benchmarks on different methods of doing things

User · Answer

Do not concatenate  It s not needed  us commas as echo can take multiple parameters  echo  Welcome     name         Regarding using single or double quotes the difference is negligible  you can do tests with large numbers of strings to test for yourself

User · Answer

I prefer this all the time and found it much easier  echo  quot Welcome   name   quot

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