stdEncode: make prefix and suffix optional

Author: pennam

src/utility/SElementBase64.cpp

@@ -56,7 +56,13 @@ static const char* CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
   int b;
   String out;
 
-  int reserveLength = 4 * ((length + 2) / 3) + ((length / 3 * 4) / 76) + strlen(prefix) + strlen(suffix);
+  int reserveLength = 4 * ((length + 2) / 3) + ((length / 3 * 4) / 76);
+  if (prefix != nullptr) {
+    reserveLength += strlen(prefix);
+  }
+  if (suffix != nullptr) {
+    reserveLength += strlen(suffix);
+  }
   out.reserve(reserveLength);
 
   if (prefix) {

src/utility/SElementBase64.h

@@ -15,6 +15,6 @@
 namespace arduino { namespace b64 {
 
     String urlEncode(const byte in[], unsigned int length);
-    String stdEncode(const byte in[], unsigned int length, const char* prefix, const char* suffix);
+    String stdEncode(const byte in[], unsigned int length, const char* prefix=nullptr, const char* suffix=nullptr);
 
 }} // arduino::b64