Replace characters in a string in Arduino

The .replace() function in Arduino allows you to replace a character or a substring with another character/substring in Arduino.

Note: This function replaces substrings in the original string itself, and does not return a new string containing the changes.

Examples are given in the code below −

Example

void setup() {
   Serial.begin(9600);
   Serial.println();
   String s1 = "Hello World";
   Serial.println(s1);
   s1.replace('e','a');
   Serial.println(s1);
   
   s1 = "Hello World";
   s1.replace("ll","gg");
   Serial.println(s1);

   s1 = "Hello World";
   s1.replace("li","gg");
   Serial.println(s1);
}
void loop() {
   // put your main code here, to run repeatedly:
}

The Serial Monitor output is shown below −

Output

As you can see, in the last attempt, the string was unchanged. This is because the substring 'li' was not part of s1. Therefore, there was nothing to replace!