Enabling printf style output method with variadic arguments

Author: aentinger

api/Print.cpp

@@ -144,6 +144,15 @@ size_t Print::print(const Printable& x)
   return x.printTo(*this);
 }
 
+size_t Print::printf(char const * fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  size_t const n = vprintf(fmt, args);
+  va_end(args);
+  return n;
+}
+
 size_t Print::println(void)
 {
   return write("\r\n");
@@ -233,6 +242,16 @@ size_t Print::println(const Printable& x)
   return n;
 }
 
+size_t Print::printfln(char const * fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  size_t n = vprintf(fmt, args);
+  va_end(args);
+  n += println();
+  return n;
+}
+
 // Private Methods /////////////////////////////////////////////////////////////
 
 size_t Print::printNumber(unsigned long n, uint8_t base)
@@ -374,3 +393,13 @@ size_t Print::printFloat(double number, uint8_t digits)
 
   return n;
 }
+
+size_t Print::vprintf(char const * fmt, va_list args)
+{
+  static size_t const MSG_BUF_SIZE = 64;
+  char msg_buf[MSG_BUF_SIZE] = {0};
+
+  int const length = vsnprintf(msg_buf, MSG_BUF_SIZE, fmt, args);
+
+  return write(msg_buf, length);
+}

api/Print.h

@@ -36,6 +36,7 @@ class Print
     size_t printNumber(unsigned long, uint8_t);
     size_t printULLNumber(unsigned long long, uint8_t);
     size_t printFloat(double, uint8_t);
+    size_t vprintf(char const * fmt, va_list args);
   protected:
     void setWriteError(int err = 1) { write_error = err; }
   public:
@@ -67,6 +68,7 @@ class Print
     size_t print(unsigned long long, int = DEC);
     size_t print(double, int = 2);
     size_t print(const Printable&);
+    size_t printf(char const * fmt, ...);
 
     size_t println(const __FlashStringHelper *);
     size_t println(const String &s);
@@ -82,5 +84,6 @@ class Print
     size_t println(double, int = 2);
     size_t println(const Printable&);
     size_t println(void);
+    size_t printfln(char const * fmt, ...);
 };