General Built-in Methods

Built-in methods

Ruby provides built-in utility methods that make it easier for programmers to perform routine tasks. The best-known built-in methods are .length(), gets, and print().

Let’s explore some commonly used built-in methods.

Quotient and remainder together

The divmod() method computes the remainder after the division of two numbers. It differs from the modulus operator % in that it returns two resulting values and the quotient.

Remember: A method in Ruby might return two or more values.

Let’s use an example program to explore the difference between the divmod() method and the % operator.

In the program above:

• We use % to calculate the remainder.

• We use built-in divmod() method, which accepts two parameters:

  • The dividend
  • The divisor

• The function then returns two values:

  • The quotient
  • The remainder

Reverse order

The reverse() method is used to access the elements of an array or string in reverse order. The result of this method can be accessed with the help of a loop. The following code will demonstrate how this method works:

In the program above:

• An array passes to the reverse() function in the for loop statement.

• Each array element is displayed in reverse order in the body of the loop.

• Similarly, the reverse() function is used to reverse the given string.

We can convert a string to an array of characters using the split() method for the given string and display each character using a for loop as follows:

Rounding off

This function rounds the provided number into the nearest integer value. For example, the values 3.1 to 3.4 are near 3, and the values 3.5 to 3.9 are near 4.

In the program above:

• We use the range method to generate values from 30 to 46 in the for loop statement.
• We convert these integers to floating-point values through division.
• In the print() statement, the program displays each floating-point value along with its floor, ceiling, and rounded approximation in each loop iteration.
  • Subtracts 0.49 from each floating-point value to display the floor value.
  • Adds 0.49 to each floating-point value to display the ceiling value. Uses the string \t, which means tab and creates multiple spaces for the tabular form of the output.

Radix converter

The hex and bin methods convert a decimal number to hexadecimal and binary, respectively. The following program demonstrates these methods in an interactive way. It takes a decimal number and converts it to the target radix, as input by the user. The program waits for the following two inputs before it runs:

• The decimal number to be converted.
• The target radix (2 or 16).

In the program above:

• We input two values—a decimal number in the sourceNum variable and the target radix in the targetRadix variable.
• We validate the targetRadix to be either 2 or 16 only.
• Then, we display the converted number using the appropriate conversion method.

Note: The prefix 0x indicates a hexadecimal number, and the prefix 0b indicates a binary number.

Sorting

The sort() function returns a list of values in ascending order. Non-numeric values are sorted based on their ASCII codes.

Here, we’ll use the sort() function to write a program that sorts characters of a string based on ASCII codes:

In the program above:

• We first create an array of integers.

• We call the sort() method in the print() statement.

• {|a, b| a <=> b} is a block that defines a condition for sorting elements in an array. The <=> operator is called the “comparison operator” and it returns -1 if the element on the left is less than the element on the right, 0 if the elements are equal, and 1 if the element on the left is greater than the element on the right.

• Then we create a string with a combination of lowercase and uppercase letters.

• We call the char.sort() method in the print() statement, which returns an array of alphabetical symbols in ascending order based on their ASCII codes.

The ASCIIAmerican Standard Code for Information Interchange is the code used for storing basic symbols, including English alphabets on a computer. codes of capital $A–Z$ are $65–90$, respectively. The ASCII codes of lowercase $a–z$ are $97–122$, respectively. Therefore, the capital letters are listed before lowercase letters. Thus, uppercase $Z$ is smaller than lowercase $a$ based on their ASCII codes.

Conversion methods

In Ruby, we have built-in conversion methods to convert data types.

• The .to_s method converts any input into strings.
• The .to_i method converts any input into an integer. The result contains only the integer at the start; for example, 12a or 12.9 becomes 12, but a12 or .9 becomes 0.
• The .to_f method converts any input into a floating-point number. The result contains only the number at the start and includes a decimal point; for example, 12a or 12 becomes 12.0, and 12.98a becomes 12.98.