Values of one type can be converted to a value of another type. For
example, the integer 4711 can be converted to the string
"4711". (These two may look similar, but they are actually
entirely different things. For example, 4711 + 3 will give
you 4714, "4711" + "3" will give you
"47113".)
Some conversions are done automatically. For example, in the
expression "hello" + 17 the integer 17 will be
automatically converted to the string "17", before the two
strings are concatenated, giving the result "hello17". But
some conversions need to be performed with a special operation, called
an explicit type conversion or cast. There is a special
cast operator, which is written as a data type between
parentheses:
(float)14 // Gives the float 14.0
(int)6.9 // Gives the int 6
(string)6.7 // Gives the string "6.7"
(float)"6.7" // Gives the float 6.7
Here is a list of some useful casts:
| Casting from | to | gives the result |
|
int
|
float
|
The floating-point number with the same value as the integer
|
|
float
|
int
|
An integer, with the fractional part ("the decimals") just
skipped
|
|
int
|
string
|
Converts the integer to a string with a number in normal base-10
notation
|
|
float
|
string
|
Converts the floating-point number to a string
|
|
string
|
int
|
Converts the first number in the string to an integer. The number
should be an integer written in normal base-10 notation.
|
|
string
|
float
|
Converts the first number, with or without decimals, in the string
to a floating-point number
|
|
string
|
program
|
If the string contains a filename, compile the file and return the
program. The results are cached.
|
|
string
|
object
|
First casts the string to a program as above, and then clones the
result. The results are cached.
|
|
array
|
array(type)
|
This recursively casts all values in the array to type.
|
|
multiset
|
array
|
The same as doing indices(multiset).
|
Sometimes you know more than what Pike does about data types, and
another use of the cast operator is to tell Pike what you know. For
example, lets say that you have a variable with the type
mixed, which means that it can contain any type of data. Lets
also say that you happen to know that that variable contains an
integer. If you want to use this value where an integer is required,
Pike might complain about it:
mixed m;
int i;
m = 18;
i = m; // This might make Pike suspicious
You can use a cast to tell Pike that m is an integer and
nothing else:
i = (int)m; // Don't worry. I promise it's an int!
