Ruby Array Find All Indexes

If a block is given instead of an argument returns the index of the first object for which the block returns true.

Ruby array find all indexes.

In ruby indexes start at zero. Ruby arrays can hold objects such as string integer fixnum hash symbol even other array objects. Since everything in ruby evaluates to true except for false and nil using all. The select method works in a similar way but it constructs a new array containing all of the elements that match.

When a size and an optional default are sent an array is created with size copies of default take notice that all elements will reference the same object default. To access a specific item or element of an array you reference its index or its position in the array. A negative index is assumed relative to the end of the array that is an index of 1 indicates the last element of the array 2 is the next to last element in the array and so on. I often need to get the indices of all the elements that match a given condition.

Array indexing starts at 0 as in c or java. Find l l. For example an array contains the following contents a 1 1 2 5 6 1 2 8 i want to know the indices of all the ones present in that array. Testing arrays for nils with enumerable all.

When the block is omitted all. Arrays are zero based. Returns a new array. In the first form if no arguments are sent the new array will be empty.

Block condition to follow return. By running the following you can achieve that. The index of the first element is zero. Index value of the array elements.

These items are called elements of the array. Find index is a array class method which returns the index of the first array. The block usage was added in 1 8 7 so to get the same functionality in an earlier version of ruby you need to utilize the find method. The second form creates a copy of the array passed as a parameter the array is generated by calling to ary on the parameter.

Uses this implied block. Arrays can hold multiple items. Without a block on an array is effectively a test to see if all the items in the collection evaluate to true or conversely if there are any false or nil values in the array. Here is a quick example.

Arrays can hold objects of any data type. Hammerhead find executes the block you provide for each element in the array. If it doesn t find anything after iterating through all of the elements it returns nil. Each element can be referred to by an index.

If the last expression in the block evaluates to true the find method returns the value and stops iterating. Index match if you do some gymnastics you can have it on one line without. Using block version in ruby 1 8 7. It is actually not that difficult to do so.