Is there a way to convert an integer to a string in PHP?
Answers
Type casting is treating a value (block of memory) referenced by a variable as being of a different type than the type the variable is declared as.
Type conversion is actually performing a conversion of that value.
In many languages, some casts (usually numeric ones) do result in conversions (this will vary quite a bit by language), but mostly it's just "treat this X as a Y".
Like most aspects of human language, unfortunately the terms are used slightly differently in different communities, mostly along language lines. For instance, see James' comment below about C++ — the word "cast" there has a much broader meaning than the above definition, which is more in the C or Java mold. And just to make things fun, the Java Language Spec actually gets into various kinds of casts, including casting conversions. But the above is a good rule of thumb.
But to take a simple case:
In Java, prior to generics it wasn't unusual to have to do a lot of typecasting when dealing with maps:
Map m = new HashMap();
m.put("one", "uno");
// This would give a compiler error, because although we know
// we'll get a String back, all the compiler knows is that it's
// an Object
String italian = m.get("one");
// This works, we're telling the compiler "trust me, it's a String"
String italian = (String)m.get("one");
Fortunately, the addition of generics addressed this, as casting in this way tends to be a fragile process with maintenance issues.
In contrast, you'd convert if you had a String of digits:
String s = "1234";
...and needed to know what number those digits represented in decimal:
// Wrong (cast)
int n = (int)s;
// Right (conversion)
int n = Integer.parseInt(s, 10);
The following is probably not the neatest way, but it works:
1> lists:flatten(io_lib:format("~p", [35365])).
"35365"
EDIT: I've found that the following function comes in useful:
%% string_format/2
%% Like io:format except it returns the evaluated string rather than write
%% it to standard output.
%% Parameters:
%% 1. format string similar to that used by io:format.
%% 2. list of values to supply to format string.
%% Returns:
%% Formatted string.
string_format(Pattern, Values) ->
lists:flatten(io_lib:format(Pattern, Values)).
EDIT 2 (in response to comments): the above function came from a small program I wrote a while back to learn Erlang. I was looking for a string-formatting function and found the behaviour of io_lib:format/2
within erl
counter-intuitive, for example:
1> io_lib:format("2 + 2 = ~p", [2+2]).
[50,32,43,32,50,32,61,32,"4"]
At the time, I was unaware of the 'auto-flattening' behaviour of output devices mentioned by @archaelus and so concluded that the above behaviour wasn't what I wanted.
This evening, I went back to this program and replaced calls to the string_format
function above with io_lib:format
. The only problems this caused were a few EUnit tests that failed because they were expecting a flattened string. These were easily fixed.
I agree with @gleber and @womble that using this function is overkill for converting an integer to a string. If that's all you need, use integer_to_list/1
. KISS!
var_dump(0 == "string");
is doing a numeric (integer) comparison
0 is an integer, so "string" is converted to an integer to do the comparison, and equates to an integer value of 0, so 0 == 0 is true
Se the comparison with various types table in the PHP documentation for details
You can use the
strval()
function to convert a number to a string.From a maintenance perspective its obvious what you are trying to do rather than some of the other more esoteric answers. Of course, it depends on your context.