String Replace ExamplesUse the Replace method on strings. Exchange substrings and characters in strings.
This page was last reviewed on Feb 23, 2023.
Replace. Programs spend their time modifying strings. Perhaps a string contains the name of an animal, but we want it to be the name of a plant.
String usage. Replace() changes the first, but also all following matching instances in the source string. A new string is returned containing the modifications.
Replace example. To start, we have a string containing the names of some animals. We replace a substring with Replace—the occurrences of "cats" are replaced with "birds."
Then We perform another replacement. We replace "and" with "or." All 3 strings are independent—strings are not modified in-place.
// Our initial string. let animals = "cats and dogs and fish" // Change "cats" to "birds." let result1 = animals.Replace("cats", "birds") // Change another word. // ... All instances of the substring are replaced. let result2 = result1.Replace("and", "or") // The three strings are separate. printfn "%s" animals printfn "%s" result1 printfn "%s" result2
cats and dogs and fish birds and dogs and fish birds or dogs or fish
Char. The Replace method can handle a single char. All instances of the char in the string are replaced with a new char. The string's length remains the same.
let code = "abcdefabc" // Use Replace to change letter "a" to underscore. let result = code.Replace('a', '_') printfn "%s" code printfn "%s" result
abcdefabc _bcdef_bc
Character array. Sometimes a replacement is too complex to be handled with a simple Replace() call. We can convert a string to a char array, and then replace characters in a for-in loop.
Here We change the colon character to a lowercase letter "A." Please note multiple replacements could occur in the loop body.
Result We convert the array to a new string with the string constructor. Our replacement is complete.
let name = ":reop:gitic:" // Convert string to an array. let array = name.ToCharArray() // Change colon character to letter "A" in string. for c in 0 .. array.Length - 1 do if array.[c] = ':' then array.[c] <- 'a' // Convert char array to string. let resultCopy = new string(array) printfn "%s" resultCopy
Some notes. The string type in F# offers other methods that change strings. For example, Insert and Remove are similar to Replace.
A common string operation. Strings are used throughout programs. And with the Replace method from the .NET Framework, we swap string fragments in a standard, optimized way in this language.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
No updates found for this page.
© 2007-2024 Sam Allen.