Examples > Strings

String Replace Function

The String replace() function allows you to replace all instances of a given character with another character. You can also use replace to replace substrings of a string with a different substring.

Relevant Groundwork

None

Hardware Required

  • MSP-EXP430G2 LaunchPad

Circuit

Only LaunchPad is required for this example.

image developed using Fritzing. For more circuit examples, see the Fritzing project page.

Schematic

Code Explanation

Caution: If you try to replace a substring that’s more than the whole string itself, nothing will be replaced. For example:.

 

  String stringOne = "dog";
  String stringTwo = stringOne.replace("twodogs", "Blah");

 

In this case, the code will compile, but stringOne will remain unchanged, since the replacement substring is more than the String itself.

Code

/*
  String replace()

 Examples of how to replace characters or substrings of a string

 created 27 July 2010
 modified 2 Apr 2012
 by Tom Igoe

 This example code is in the public domain. 
 */

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);

  // send an intro:
  Serial.println("\n\nString  replace:\n");
  Serial.println();
}

void loop() {
  String stringOne = "<HTML><HEAD><BODY>"";
  Serial.println(stringOne);
  // replace() changes all instances of one substring with another:
  // first, make a copy of th original string:
  String stringTwo = stringOne;
  // then perform the replacements:
  stringTwo.replace("<", "</");
  // print the original:
  Serial.println("Original string: " + stringOne);
  // and print the modified string:
  Serial.println("Modified string: " + stringTwo);

  // you can also use replace() on single characters:
  String normalString = "bookkeeper";
  Serial.println("normal: " + normalString);
  String leetString = normalString;
  leetString.replace('o', '0');
  leetString.replace('e', '3');
  Serial.println("l33tspeak: " + leetString);

  // do nothing while true:
  while(true);
}

Working Video

Try it out:

– Replace all the nouns in a string with funny names

 

See Also

 

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