Ruby | String index Method

index is a String class method in Ruby which is used to returns the index of the first occurrence of the given substring or pattern (regexp) in the given string. It specifies the position in the string to begin the search if the second parameter is present. It will return nil if not found.

Syntax: str.index()

Parameters: Here, str is the given string.

Returns: Index of the first occurrence of the given substring or pattern (regexp) in str.

Example 1:

# Ruby program to demonstrate
# the index method

# Taking a string and
# using the method
puts "Sample".index('m')
puts "Program".index('gr')
puts "Checking".index('a')

Output:

2
3

Example 2:

# Ruby program to demonstrate
# the index method

# Taking a string and
# using the method
puts "Mangal".index(?g)
puts "Language".index(/[aeiou]/, -3)

Output:

3
5