Add Print::printf() method

Author: kuba2k2

api/Print.cpp

@@ -16,6 +16,7 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
+#include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -385,3 +386,21 @@ size_t Print::printFloat(double number, int digits)
 
   return n;
 }
+
+size_t Print::printf(const char *format, ...)
+{
+  va_list args;
+  va_list copy;
+  va_start(args, format);
+  int len = vsnprintf(NULL, 0, format, args);
+  if (len <= 0) {
+    va_end(args);
+    return 0;
+  }
+  char *buf = (char *)malloc(len + 1);
+  len = vsnprintf(buf, len + 1, format, args);
+  va_end(args);
+  len = write(buf, len);
+  free(buf);
+  return len;
+}

api/Print.h

@@ -90,6 +90,8 @@ class Print
     size_t println(void);
 
     virtual void flush() { /* Empty implementation for backward compatibility */ }
+
+    size_t printf(const char *format, ...) __attribute__((format (printf, 2, 3)));
 };
 
 }