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instance method

Kernel#Integer

Integer(object, base = 0, exception: true) → integer or nil

static VALUE
rb_f_integer(int argc, VALUE *argv, VALUE obj)
{
    VALUE arg = Qnil, opts = Qnil;
    int base = 0;

    if (argc > 1) {
        int narg = 1;
        VALUE vbase = rb_check_to_int(argv[1]);
        if (!NIL_P(vbase)) {
            base = NUM2INT(vbase);
            narg = 2;
        }
        if (argc > narg) {
            VALUE hash = rb_check_hash_type(argv[argc-1]);
            if (!NIL_P(hash)) {
                opts = rb_extract_keywords(&hash);
                if (!hash) --argc;
            }
        }
    }
    rb_check_arity(argc, 1, 2);
    arg = argv[0];

    return rb_convert_to_integer(arg, base, opts_exception_p(opts));
}

Returns an integer converted from object.

Tries to convert object to an integer using to_int first and to_i second; see below for exceptions.

With a non-zero base, object must be a string or convertible to a string.

numeric objects

With integer argument object given, returns object:

Example

Integer(1)                # => 1
Integer(-1)               # => -1

With floating-point argument object given, returns object truncated to an intger:

Example

Integer(1.9)              # => 1  # Rounds toward zero.
Integer(-1.9)             # => -1 # Rounds toward zero.

string objects

With string argument object and zero base given, returns object converted to an integer in base 10:

Example

Integer('100')    # => 100
Integer('-100')   # => -100

With base zero, string object may contain leading characters to specify the actual base (radix indicator):

Example

Integer('0100')  # => 64  # Leading '0' specifies base 8.
Integer('0b100') # => 4   # Leading '0b', specifies base 2.
Integer('0x100') # => 256 # Leading '0x' specifies base 16.

With a positive base (in range 2..36) given, returns object converted to an integer in the given base:

Example

Integer('100', 2)   # => 4
Integer('100', 8)   # => 64
Integer('-100', 16) # => -256

With a negative base (in range -36..-2) given, returns object converted to an integer in the radix indicator if exists or -base:

Example

Integer('0x100', -2)   # => 256
Integer('100', -2)     # => 4
Integer('0b100', -8)   # => 4
Integer('100', -8)     # => 64
Integer('0o100', -10)  # => 64
Integer('100', -10)    # => 100

base -1 is equal the -10 case.

When converting strings, surrounding whitespace and embedded underscores are allowed and ignored:

Example

Integer(' 100 ')      # => 100
Integer('-1_0_0', 16) # => -256

other classes

Examples with object of various other classes:

Example

Integer(Rational(9, 10)) # => 0  # Rounds toward zero.
Integer(Complex(2, 0))   # => 2  # Imaginary part must be zero.
Integer(Time.now)        # => 1650974042

keywords

With optional keyword argument exception given as true (the default):

Raises TypeError if object does not respond to to_int or to_i.
Raises TypeError if object is nil.
Raise ArgumentError if object is an invalid string.

With exception given as false, an exception of any kind is suppressed and nil is returned.

See also #Hash #iterator? #gsub #j also in 4.1 · 4.0 · 3.4 · 3.3 · 3.1 · 3.0

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