Added String length() example.

build/shared/examples/8.Strings/StringLength/StringLength.pde

@@ -0,0 +1,45 @@
+/*
+  String length() 
+ 
+ Examples of how to use length() in a String. 
+ Open the Serial Monitor and start sending characters to see the results.
+ 
+ created 1 Aug 2010
+ by Tom Igoe
+ 
+ This example code is in the public domain.
+ */
+String txtMsg = "";                         // a string for incoming text
+int lastStringLength = txtString.length();  //previous lenngth of the String
+
+void setup() {
+  // open the serial port:
+  Serial.begin(9600);
+}
+
+void loop() {
+  // add any incoming characters to the String:
+  while (Serial.available() > 0) {
+    char inChar = Serial.read();
+    txtMsg += inChar;
+  } 
+
+  // print the message and a notice if it's changed:
+  if (txtMsg.length() != lastStringLength) {
+    Serial.println(txtMsg);
+    Serial.println(txtMsg.length());
+    // if the String's longer than 140 characters, complain:
+    if (txtMsg.length() < 140) {
+      Serial.println("That's a perfectly acceptable text message");
+    } 
+    else {
+      Serial.println("That's too long for a text message."); 
+    }
+    // note the length for next time through the loop:
+    lastStringLength = txtMsg.length();
+  }
+
+}
+
+
+