These are the basic types in Pike:
They are basic in the sense that data items of these data types
can't contain other data items. When a data item of a basic type
is stored in a variable, it is the data item itself that is stored,
and not just a reference to it, as explained earlier.
The Data Type int
Integer values can be written in several ways:
In decimal (that is, base 10) format, i. e. the normal way to write
numbers, such as 78.
In octal (that is, base 8) format, with a leading 0, such
as 0116 (which is equal to 78 in decimal
In hexadecimal (that is, base 16) format, with a leading
0x, such as 0x4e (which is also equal to 78
in decimal notation).
In binary (ones and zeroes) format, with aleading 0b, such
as 0b1001110 (which again is equal to 78 in decimal
As a character literal within single quotes, which will give the
internal character code for that character. For example, 'N'
will give the character code for the character N, which is
usually equal to 78.
You can use normal arithmetic operations, such as addition and
multiplication, with integers, but you can also consider integers as
sequences of bits and, apply bitwise operations on them.
For example, the integer value 247 is stored internally as
the sequence of bits 1111011, and you could left-shift it three
positions with the expression 247 << 3, giving the bit
pattern 1111011000, which is equal to 1976.
Integers in Pike can be very large. For small integers (usually
less than 2 billion or so), Pike will use the computer's own,
hardware-supported way of representing integers. For larger integers,
Pike will use "bignums". These are slower, but can be arbitrarily
large. Just like the smaller integers, bignums are represented
exactly, without any rounding errors.
As a programmer, you will usually not need to worry about the
difference between bignums and smaller integers. There may however be
some operations, for example certain methods in certain modules, that
cannot handle bignums but work with smaller integers.
Some operations that you can apply to integers:
- Check if it is an integer
The function intp returns 1 if the value
something is an integer, otherwise 0. Example:
write("The integer is " + u + ".\n");
write("It is not an integer.\n");
- Get a random number
random(limit) returns a random value which is
greater or equal to 0 and less than the integer
- Reverse the bits
reverse(integer-value) returns an integer with the
bits in the integer-value in reverse order.
The Data Type float
Real numbers, which are numbers that can have a fractional part,
such as 18.34 and -1000.03, are represented in the
computer as floating-point numbers. Floating-point numbers can
be used to represent very large numbers, but with limited precision.
The number of significant digits is the same, no matter the magnitude
of the value.
You can write floating-point values in two ways, as usual with
decimals, or in exponential form with an e:
1.0e6 // 1.0 times 10 to the power of 6, i. e. one million
2.0e-6 // 2.0 times 10 to the power of -6, i. e. two one-millionths
-1.0e-2 // Minus one hundredth
Some operations that you can apply to floating-point numbers:
- Check if it is a floating-point number
The function floatp returns 1 if the value
something is a floating-point number, otherwise 0.
- Round downwards
floor(float-value) returns the largest integer that
is less than or equal to float-value, but as a floating-point
number. For example, floor(7.3) gives 7.0 (and not the
integer 7). If you do want the integer value, you can use an
explicit type conversion: (int)7.3 gives you the integer
- Round upwards
ceil(float-value) returns the smallest integer that
is greater than or equal to float-value, as a floating-point
number. For example, ceil(7.3) gives 8.0 (and not the
The Data Type string
Strings are sequences of characters, and are written within double
quotes (") in Pike:
"Woe to you, oh Earth and Sea"
The last one is the empty string. Special characters, such as the
double quote character, need to be preceded by a backslash character
\" to get a double quote (") in the string
\\ to get a backslash character (\)
\n to get a newline character
\t to get a tab character
\r to get a carriage return
\0 to get a NUL character, i. e. the character with
character code 0
Here are some examples of strings:
"One line\nAnother line\nA third line"
"Strings are written within \" characters."
You can use character codes instead of the characters themselves.
If you write \d followed by a decimal (that is, normal base 10) number,
it will be replaced by the character with that character code.
The same goes for \x followed by a hexadecimal (base 16) number,
and a single \ followed by an octal (that is, base 8) number.
The \0 is actually an example of this.
These four strings are identical:
Strings in Pike are what we call "shared", which means that if two
or more strings contain exactly the same characters, there will still
be only one copy of it.
Some operations that you can apply to strings:
- Check if it is a string
The function stringp returns 1 if the value
something is a string, otherwise 0.
Strings can be concatenated with the + operator:
string s1 = "Hello";
string s2 = " ";
string s3 = "world!";
write(s1 + s2 + s3 + "\n");
- Concatenation of string literals
String literals, who are strings within double quotes that
are written in a program, can be concatenated by just putting them
after each other:
write("Hello" " " "world!" + "\n");
Pike has many powerful built-in operations for working with
strings. Read more about those in the chapter about string handling,