Arduino String Function: REPLACE, SUBSTRING ETC.
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Table of Contents
- ARDUINO STRING FUNCTION
- charAt()
- compareTo()
- concat()
- endsWith()
- equals()
- equalsIgnoreCase()
- indexOf()
- lastIndexOf()
- length()
- remove()
- replace()
- setCharAt()
- startsWith()
- substring()
- toLowerCase()
- toUpperCase()
- trim()
In this tutorial, we will cover all Arduino String Function like string replace function Arduino, string compare function in Arduino, string copy function Arduino, etc.
For datatype conversion like; int to string function arduino, string to int arduino, string to char arduino follow the link.
ARDUINO STRING FUNCTION
charAt()
myString.charAt(n): Access a particular character of the String.
where,
-
- myString → String
- n → Integer
Returns: character value at nth index
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "HELLO"; char ch; void setup() { Serial.begin(9600); delay(1000); ch = myString.charAt(2); Serial.print("myString: "); Serial.print(myString); Serial.print(", myString.charAt(2): "); Serial.println(ch); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
compareTo()
myString.compareTo(myString2): Compares two Strings, testing whether one comes before or after the other, or whether they’re equal.
The strings are compared character by character, according to ASCII values of the characters.
Example: ‘A’, ‘B’, … ‘a’, ‘b’, … ‘a’ comes before ‘b’ but also ‘a’ comes after ‘A’ according to ASCII
You can also use operators like == and != to check if string equals to or not equals to
where,
-
- myString → String
- myString2 → String
Returns:
-
- Negative (–)number if myString comes before myString2
- Positive (+)number if myString comes after myString2
- Zero (0) if String equals myString2
OUTPUT
concat()
myString.concat(parameter): Appends the parameter to a String.
where,
-
- myString → String
- parameter → can be String, string, char, byte, int, unsigned int, long, unsigned long, float, double, __FlashStringHelper(F() macro)
Returns: true (1) or false (0) (can be store in int or boolean)
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "Apple: "; int val = 5, n; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("val = "); Serial.println(val); n = myString.concat(val); Serial.print("Returns = "); Serial.println(n); Serial.print("myString.concat(val) = "); Serial.println(myString); /* You can also add two string using + sign, / if you find some issue you can convert it into string to use + operator / String(val) or String(n) like this */ myString = myString + val; Serial.print("myString after + = "); Serial.println(myString); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
endsWith()
myString.endsWith(myString2): Checks if myString ends with the characters of myString2. This function is case sensitive.
where,
-
- myString → String
- myString2 → String
Returns: true (1) or false (0)
-
- 1: if myString ends with the characters of myString2
- 0: if myString doesn’t ends with the characters of myString2
OUTPUT
equals()
myString.equals(myString2): Compares two Strings for equality. The comparison is case-sensitive, meaning the String “apple” is not equal to the String “APPLE” You can also use operators like == and != to check if string equals to or not equals to
where
-
- myString → String
- myString2 → String
Returns: true (1) or false (0)
-
- 1: if myString equals (exact match) myString2
- 0: if myString doesn’t match
OUTPUT
equalsIgnoreCase()
myString.equalsIgnoreCase(myString2): Compares two Strings for equality. The comparison is not case-sensitive, meaning the String “apple” is equal to the String “APPLE”
where,
-
- myString → String
- myString2 → String
Returns: true (1) or false (0)
-
- 1: if myString equals myString2 (not case sensitive)
- 0: if myString doesn’t match
OUTPUT
indexOf()
myString.indexOf(val): Locates a character or String within another String. By default, searches from the beginning of the String, but can also start from a given index, using myString.indexOf(val, from)
where
-
- myString → String
- val → char, String
- from → Integer
Returns: The index of val within the String, or -1 if not found.
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "apple"; char val = 'e', val2 = 'E'; int from = 1; int n; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("val = "); Serial.println(val); Serial.print("val2 = "); Serial.println(val2); Serial.print("from = "); Serial.println(1); Serial.println(); Serial.println("### myString.indexOf(val)"); n = myString.indexOf(val); Serial.print("Return Index = "); Serial.println(n); Serial.println("### myString.indexOf(val, from)"); n = myString.indexOf(val, from); Serial.print("Return Index = "); Serial.println(n); Serial.println("### myString.indexOf(val2)"); n = myString.indexOf(val2); Serial.print("Return Index = "); Serial.println(n); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
lastIndexOf()
myString.lastIndexOf(val): Locates a character or String within another String. By default, searches from the END of the String, but can work backwards from a given index using myString.lastIndexOf(val, from).
where
-
- myString → String
- val → char, String
- from → Integer
Returns: The index of val within the String, or -1 if not found.
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "apple"; char val = 'p', val2 = 'A'; int from = 1; int n; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("val = "); Serial.println(val); Serial.print("val2 = "); Serial.println(val2); Serial.print("from = "); Serial.println(1); Serial.println(); // This will return 2, as function we starts reading back from the last index Serial.println("### myString.lastIndexOf(val)"); n = myString.lastIndexOf(val); Serial.print("Return Index = "); Serial.println(n); // This will return 1, as we starts reading back from index 1 'p' at index 2 is not read by function Serial.println("### myString.lastIndexOf(val, from)"); n = myString.lastIndexOf(val, from); Serial.print("Return Index = "); Serial.println(n); Serial.println("### myString.lastIndexOf(val2)"); n = myString.lastIndexOf(val2); Serial.print("Return Index = "); Serial.println(n); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
length()
myString.length(): Returns length of String (number of characters present)
where
-
- myString → String
Returns: Integer
// Tutorial: https://pijaeducation.com/arduino-string-function/ /* myString.length(): Returns length of String (number of characters present) Returns: Integer myString → String */ String myString = "apple"; String myString2 = "apples are good for health"; int n; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("myString2 = "); Serial.println(myString2); Serial.println(); Serial.println("### myString.length()"); n = myString.length(); Serial.print("Length of String = "); Serial.println(n); Serial.println("### myString2.length()"); n = myString2.length(); Serial.print("Length of String 2 = "); Serial.println(n); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
remove()
myString.remove(index): Remove charaters of a String from index to end
myString.remove(index, n): Remove n number of charaters of a String from the index
where,
-
- myString → String
- index → integer
- n → integer
Returns: Nothing
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "apples are good for health"; int index = 7, n = 4; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.println(); Serial.println("### myString.remove(index, n)"); myString.remove(index, n); Serial.print("New String = "); Serial.println(myString); Serial.println(); Serial.println("### myString.remove(index)"); myString.remove(index); Serial.print("New String = "); Serial.println(myString); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
replace()
myString.replace(substring1, substring2): substring2 will replace substring1 in myString where,
-
- myString → String
- substring1 → String
- substring2 → String
Returns: Nothing
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "apples are good for health"; String substring1 = "are", substring2 = "***"; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("substring1 = "); Serial.println(substring1); Serial.print("substring2 = "); Serial.println(substring2); Serial.println(); Serial.println("### myString.replace(substring1, substring2)"); myString.replace(substring1, substring2); Serial.print("myString = "); Serial.println(myString); Serial.print("substring1 = "); Serial.println(substring1); Serial.print("substring2 = "); Serial.println(substring2); Serial.println(); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
setCharAt()
myString.setCharAt(index, c): This will set or change character at particular index without changing string length
where,
-
- myString → String
- index → Integer
- c → char
Returns: Nothing
// Tutorial: https://pijaeducation.com/arduino-string-function/ String myString = "Applet"; int index = 5; char c = 's'; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("index = "); Serial.println(index); Serial.print("c = "); Serial.println(c); Serial.println(); Serial.println("### myString.setCharAt(index, c)"); myString.setCharAt(index, c); Serial.print("myString = "); Serial.println(myString); } void loop() { // put your main code here, to run repeatedly: }OUTPUT
startsWith()
myString.startsWith(myString2): Checks if myString starts with the characters of myString2. This function is case sensitive.
where,
-
- myString → String
- myString2 → String
Returns: true (1) or false (0)
-
- 1: if myString starts with the characters of myString2
- 0: if myString doesn’t starts with the characters of myString2
OUTPUT
substring()
myString.substring(fromIndex): Returns substring, substring will be string from the ‘fromIndex’ to the ‘last’ of the myString
myString.substring(fromIndex, toIndex): substring will be string from the ‘fromIndex’ to ‘toIndex – 1’ of the myString
For example: if fromIndex = 1 and toIndex = 4, then substring length will be 4 – 1 = 3
where,
-
- myString → String
- fromIndex → Integer
- toIndex → Integer
Returns: String
// TutoIndexrial: https://pijaeducation.com/arduino-string-function/ String myString = "This is an apple"; String myString2; String myString3; int fromIndex = 2, toIndex = 9; void setup() { Serial.begin(9600); delay(200); Serial.print("myString ="); Serial.println(myString); Serial.print("String Length = "); Serial.println(myString.length()); Serial.print("fromIndex = "); Serial.println(fromIndex); Serial.print("toIndex = "); Serial.println(toIndex); Serial.println(); Serial.println("### myString.substring(fromIndex)"); myString2 = myString.substring(fromIndex); Serial.print("myString2 ="); Serial.println(myString2); Serial.print("String Length = "); Serial.println(myString2.length()); Serial.println(); Serial.println("### myString.substring(fromIndex, toIndex)"); myString3 = myString.substring(fromIndex, toIndex); Serial.print("myString3 ="); Serial.println(myString3); Serial.print("String Length = "); Serial.println(myString3.length()); } void loop() { // put your main code here, toIndex run repeatedly: }OUTPUT
toLowerCase()
myString.toLowerCase(): Will convert myString characters into lower case
where,
-
- myString → String
Returns: Nothing
// TutoIndexrial: https://pijaeducation.com/arduino-string-function/ String myString = "This is an apple"; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.println(); Serial.println("### myString.toLowerCase()"); myString.toLowerCase(); Serial.print("myString = "); Serial.println(myString); } void loop() { }OUTPUT
toUpperCase()
myString.toUpperCase(): Will convert myString characters into upper case
where,
-
- myString → String
Returns: Nothing
// TutoIndexrial: https://pijaeducation.com/arduino-string-function/ String myString = "This is an apple"; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.println(); Serial.println("### myString.toUpperCase()"); myString.toUpperCase(); Serial.print("myString = "); Serial.println(myString); } void loop() { }OUTPUT
trim()
myString.trim(): Will remove leading and trailing whitespaces from the string
where,
-
- myString → String
Returns: Nothing
// TutoIndexrial: https://pijaeducation.com/arduino-string-function/ String myString = " This is an apple "; void setup() { Serial.begin(9600); delay(200); Serial.print("myString = "); Serial.println(myString); Serial.print("String Length = "); Serial.println(myString.length()); Serial.println(); Serial.println("### myString.trim()"); myString.trim(); Serial.print("myString = "); Serial.println(myString); Serial.print("String Length = "); Serial.println(myString.length()); } void loop() { }OUTPUT
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