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Reference for Wiring version 1.0 Build 0100+ If you have a previous version, use the reference included with your software. If see any errors or have any comments, let us know.

Class | String
Name |

### charAt()

Examples |
    // declares s1 with an initial string
    String s1 = String("string number one");
    byte bytes[20];  // array of byte.
    char array[20];  // array of char.

    void setup() {
      Serial.begin(9600);
      // turn ON wiring hardware LED
      pinMode(WLED, OUTPUT);
      digitalWrite(WLED, HIGH);

      // s2 holds "10000"
      String s2 = String(10000);
      Serial.println("s2 holds: " + s2);

      // s3 holds "567000"
      String s3 = String(567000, DEC);
      Serial.println("s3 holds: " + s3);

      // s4 holds "string number four"
      String s4 = "string number four";
      Serial.println("s4 holds: " + s4);

      // use + operator to add a string
      s4 += " plus another part";
      // user + operator when printing to serial
      Serial.println("now s4 holds: " + s4);

      // get character at position 5
      char c = s4.charAt(5);
      Serial.print ("c holds: ");
      Serial.println(c);  // prints 'g'

      // s5 holds "string number one"
      String s5 = String("string number one");

      int cmp = s1.compareTo(s5);  // compare s1 to s5
      if (cmp == 0) {
        Serial.println("s1 and s5 are equal");  // prints equal
      }
      else {
        Serial.println("s1 and s5 are different");
      }

      // check if s5 ends with "one"
      if (s5.endsWith("one"))
        // prints "s5 ends with "one""
        Serial.println("s5 ends with one");

      if (s1.equals(s5))  // check if s1 equal to s5
          Serial.println("s1 and s5 are equal");  // prints equal

      // s6 holds "string NUMBER one"
      String s6 = String("string NUMBER one");
      // check if s5 and s6 are equal ignoring case differences
      if (s5.equalsIgnoreCase(s6))
        // prints equal
        Serial.println("s6 and s5 are equal ignoring the case");

      Serial.print ("index of char R pn s6 is: ");
      Serial.println(s6.indexOf('R'), DEC);  // prints 12

      Serial.print ("index of char R on s6 from index 13 is: ");
      // prints -1, not found
      Serial.println(s6.indexOf('R', 13), DEC);

      String s7 = s6.substring(7, 13);
      Serial.println("s7 is: "+s7);  // prints "NUMBER"

      Serial.print ("index of string NUMBER on s6 is: ");
      Serial.println(s6.indexOf(s7), DEC);  // prints 7

      Serial.print ("last index of char 'n' on s6 is: ");
      Serial.println(s6.lastIndexOf('n'), DEC);  // prints 15

      Serial.print ("length of s6 is: ");
      Serial.println(s6.length(), DEC);  // prints 17

      // set character at index 15 to 'N'
      s6.setCharAt(15, 'N');
      // prints "string NUMBER oNe"
      Serial.println("s6 is: "+s6);

      // check if s6 starts with "string"
      if (s6.startsWith("string"))
        // s6 starts with "string" string
        Serial.println("s6 starts with string");

      // prints "string number one"
      s6.toLowerCase();
      Serial.println("s6 to lower case is: "+s6);

      // prints "STRING NUMBER ONE"
      s6.toUpperCase();
      Serial.println("s6 to upper case is: "+s6);

      s6.concat(" plus spaces at the end   ");  // concat a string
      // prints "STRING NUMBER ONE plus spaces at the end   "
      Serial.println("s6 is: "+s6);

      // prints "STRING NUMBER ONE plus spaces at the end"
      s6.trim();
      Serial.println("trim of s6 is: "+s6);

      // prints "STRING NUMBER ONE plus spac5s at th5 5nd"
      s6.replace('e', '5');
      Serial.println("s6 is: "+s6);

      // get the byte array in the array byte.
      s6.getBytes(bytes, 20);
      Serial.print ("array byte. is: ");
      for (int i=0; i<20; i++) {
        // prints "S T R I N G   N U M B E R   O N E   p"
        Serial.write(bytes[i]);
        Serial.print(" ");
      }
      Serial.println();
      Serial.print ("array array is: ");
      s6.toCharArray(array, 20);
      Serial.println(array);  // Prints "STRING NUMBER ONE p"
    }

    void loop() {

    }
Description | Returns the character at the specified index. An index ranges from 0 to the length of the string minus 1. The first character of the sequence is at index 0, the next at index 1, etc.
Syntax |
    charAt(index)
Parameters |

index | int: the index of the character

Returns | char
Usage | Application

Updated on July 07, 2011 11:09:03pm PDT