From 7dea0522f48641106f92b1511b9e62ee46f8e2dc Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Fri, 18 Mar 2011 21:45:27 -0400
Subject: Starting to distinguish between empty strings and invalid (null)
 ones.

---
 cores/arduino/WString.cpp | 12 ++++++------
 cores/arduino/WString.h   |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/cores/arduino/WString.cpp b/cores/arduino/WString.cpp
index 41c80e8..516bd20 100644
--- a/cores/arduino/WString.cpp
+++ b/cores/arduino/WString.cpp
@@ -114,7 +114,7 @@ inline void String::init(void)
 
 unsigned char String::reserve(unsigned int size)
 {
-	if (capacity >= size) return 1;
+	if (buffer && capacity >= size) return 1;
 	if (changeBuffer(size)) {
 		if (len == 0) buffer[0] = 0;
 		return 1;
@@ -139,11 +139,6 @@ unsigned char String::changeBuffer(unsigned int maxStrLen)
 
 String & String::copy(const char *cstr, unsigned int length)
 {
-	if (length == 0) {
-		if (buffer) buffer[0] = 0;
-		len = 0;
-		return *this;
-	}
 	if (!reserve(length)) {
 		if (buffer) {
 			free(buffer);
@@ -204,6 +199,11 @@ String & String::operator = (const char *cstr)
 	if (cstr) {
 		copy(cstr, strlen(cstr));
 	} else {
+		if (buffer) {
+			free(buffer);
+			capacity = 0;
+			buffer = NULL;
+		}
 		len = 0;
 	}
 	return *this;
diff --git a/cores/arduino/WString.h b/cores/arduino/WString.h
index 6c07427..18b6541 100644
--- a/cores/arduino/WString.h
+++ b/cores/arduino/WString.h
@@ -43,7 +43,7 @@ class String
 {
 public:
 	// constructors
-	String(const char *cstr = NULL);
+	String(const char *cstr = "");
 	String(const String &str);
 	#ifdef __GXX_EXPERIMENTAL_CXX0X__
 	String(String &&rval);
-- 
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