String Manipulation

F# provides several functions and methods for string manipulation.

Split

The split function splits a string into an array of substrings based on a specified separator:

let sentence = "OCaml, Standard ML, F#"
let names = sentence.Split ","
// val names: string array = [|"OCaml"; " Standard ML"; " F#"|]

Replace

The replace function replaces all occurrences of a specified string with another string:

let sentence = "OCaml, Standard ML, F#"
let updatedSentence = sentence.Replace("Standard ML","Haskell")
// val updatedSentence: string = "OCaml, Haskell, F#"

Substring

The substring function returns a substring from a specified starting index to an optional ending index:

let sentence = "OCaml, Standard ML, F#"
let subSentence = sentence.Substring(0, 5)
// val subSentence: string = "OCaml"

Trim

The trim function removes all leading and trailing white space characters from a string:

let sentence = "  F# is awesome.   "
let trimmedSentence = sentence.Trim()
// val trimmedSentence: string = "F# is awesome."

Obs: The F# standard library provides a module System.String that contains a variety of functions for working with strings.

Concat

The String.concat function is used to join a sequence of strings into a single string with a delimeter:

let strings = [ "OCaml"; "Standard ML"; "F#" ]
let fullString = String.concat ", " strings
// val fullString: string = "OCaml, Standard ML, F#"

Length

The String.length function is used to returns the value of length of the string:

let content = "F# for fun and profit"
let strSize = String.length content
// val strSize: int = 21