diff --git a/src/convert/inttostr.cpp b/src/convert/inttostr.cpp
index b9a8d6d..89d9272 100644
--- a/src/convert/inttostr.cpp
+++ b/src/convert/inttostr.cpp
@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2021, Tomasz Sowa
+ * Copyright (c) 2021-2022, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -41,114 +41,114 @@
 namespace pt
 {
 
-std::string to_str(unsigned long long value, int base)
+std::string to_str(unsigned long long value, int base, size_t min_width)
 {
 	std::string res;
-	Toa(value, res, false, base);
+	Toa(value, res, false, base, min_width);
 
 	return res;
 }
 
 
-std::string to_str(long long value, int base)
+std::string to_str(long long value, int base, size_t min_width)
 {
 	std::string res;
-	Toa(value, res, false, base);
+	Toa(value, res, false, base, min_width);
 
 	return res;
 }
 
 
-std::string to_str(unsigned long value, int base)
+std::string to_str(unsigned long value, int base, size_t min_width)
 {
-	return to_str(static_cast<unsigned long long>(value), base);
+	return to_str(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::string to_str(long value, int base)
+std::string to_str(long value, int base, size_t min_width)
 {
-	return to_str(static_cast<long long>(value), base);
+	return to_str(static_cast<long long>(value), base, min_width);
 }
 
 
-std::string to_str(unsigned int value, int base)
+std::string to_str(unsigned int value, int base, size_t min_width)
 {
-	return to_str(static_cast<unsigned long long>(value), base);
+	return to_str(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::string to_str(int value, int base)
+std::string to_str(int value, int base, size_t min_width)
 {
-	return to_str(static_cast<long long>(value), base);
+	return to_str(static_cast<long long>(value), base, min_width);
 }
 
 
-std::string to_str(unsigned short value, int base)
+std::string to_str(unsigned short value, int base, size_t min_width)
 {
-	return to_str(static_cast<unsigned long long>(value), base);
+	return to_str(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::string to_str(short value, int base)
+std::string to_str(short value, int base, size_t min_width)
 {
-	return to_str(static_cast<long long>(value), base);
+	return to_str(static_cast<long long>(value), base, min_width);
 }
 
 
 
 
 
-std::wstring to_wstr(unsigned long long value, int base)
+std::wstring to_wstr(unsigned long long value, int base, size_t min_width)
 {
 	std::wstring res;
-	Toa(value, res, false, base);
+	Toa(value, res, false, base, min_width);
 
 	return res;
 }
 
 
-std::wstring to_wstr(long long value, int base)
+std::wstring to_wstr(long long value, int base, size_t min_width)
 {
 	std::wstring res;
-	Toa(value, res, false, base);
+	Toa(value, res, false, base, min_width);
 
 	return res;
 }
 
 
-std::wstring to_wstr(unsigned long value, int base)
+std::wstring to_wstr(unsigned long value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<unsigned long long>(value), base);
+	return to_wstr(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::wstring to_wstr(long value, int base)
+std::wstring to_wstr(long value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<long long>(value), base);
+	return to_wstr(static_cast<long long>(value), base, min_width);
 }
 
 
-std::wstring to_wstr(unsigned int value, int base)
+std::wstring to_wstr(unsigned int value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<unsigned long long>(value), base);
+	return to_wstr(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::wstring to_wstr(int value, int base)
+std::wstring to_wstr(int value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<long long>(value), base);
+	return to_wstr(static_cast<long long>(value), base, min_width);
 }
 
 
-std::wstring to_wstr(unsigned short value, int base)
+std::wstring to_wstr(unsigned short value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<unsigned long long>(value), base);
+	return to_wstr(static_cast<unsigned long long>(value), base, min_width);
 }
 
 
-std::wstring to_wstr(short value, int base)
+std::wstring to_wstr(short value, int base, size_t min_width)
 {
-	return to_wstr(static_cast<long long>(value), base);
+	return to_wstr(static_cast<long long>(value), base, min_width);
 }
 
 
diff --git a/src/convert/inttostr.h b/src/convert/inttostr.h
index f134dc8..bac0f1d 100644
--- a/src/convert/inttostr.h
+++ b/src/convert/inttostr.h
@@ -5,7 +5,7 @@
  */
 
 /* 
- * Copyright (c) 2012-2021, Tomasz Sowa
+ * Copyright (c) 2012-2022, Tomasz Sowa
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
@@ -52,8 +52,9 @@ namespace pt
 
 // if the buffer is too small it will be terminated at the beginning (empty string)
 // and the function returns false
+// min_width - if greater than zero then it is used for zero padding
 template<class CharType>
-bool Toa(unsigned long long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(unsigned long long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = nullptr, size_t min_width = 0)
 {
 size_t i1, i2;
 long rest;
@@ -77,6 +78,14 @@ long rest;
 	}
 	while(value != 0 && i2 < buf_len);
 
+	if( min_width > 0 )
+	{
+		for( ; i2 < min_width && i2 < buf_len ; ++i2)
+		{
+			buffer[i2] = '0';
+		}
+	}
+
 	if( i2 >= buf_len )
 	{
 		buffer[0] = 0; // ops, the buffer was too small
@@ -106,7 +115,7 @@ return true;
 // if the buffer is too small it will be terminated at the beginning (empty string)
 // and the function returns false
 template<class CharType>
-bool Toa(long long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(long long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = nullptr, size_t min_width = 0)
 {
 	if( len_out )
 		*len_out = 0;
@@ -126,7 +135,7 @@ bool Toa(long long value, CharType * buffer, size_t buf_len, int base = 10, size
 		is_sign   = true;
 	}
 
-	bool res = Toa(static_cast<unsigned long long>(value), buf, buf_len, base, len_out);
+	bool res = Toa(static_cast<unsigned long long>(value), buf, buf_len, base, len_out, min_width);
 
 	if( res )
 	{
@@ -146,44 +155,44 @@ return res;
 
 
 template<class CharType>
-bool Toa(unsigned long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(unsigned long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 template<class CharType>
-bool Toa(long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(long value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 
 
 template<class CharType>
-bool Toa(unsigned int value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(unsigned int value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 
 template<class CharType>
-bool Toa(int value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(int value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 
 template<class CharType>
-bool Toa(unsigned short value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(unsigned short value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<unsigned long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 
 template<class CharType>
-bool Toa(short value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0)
+bool Toa(short value, CharType * buffer, size_t buf_len, int base = 10, size_t * len_out = 0, size_t min_width = 0)
 {
-	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out);
+	return Toa(static_cast<long long>(value), buffer, buf_len, base, len_out, min_width);
 }
 
 
@@ -192,7 +201,7 @@ bool Toa(short value, CharType * buffer, size_t buf_len, int base = 10, size_t *
 
 
 template<class StringType>
-void Toa(unsigned long long value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(unsigned long long value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
 	typename StringType::value_type buffer[50];
 	size_t buffer_len = sizeof(buffer) / sizeof(wchar_t);
@@ -204,13 +213,13 @@ void Toa(unsigned long long value, StringType & res, bool clear_string = true, i
 	 * the size of the buffer is sufficient so the status should always be true
 	 */
 	size_t len_out;
-	Toa(value, buffer, buffer_len, base, &len_out);
+	Toa(value, buffer, buffer_len, base, &len_out, min_width);
 	res.append(buffer, len_out);
 }
 
 
 template<class StringType>
-void Toa(long long value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(long long value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
 	typename StringType::value_type buffer[50];
 	size_t buffer_len = sizeof(buffer) / sizeof(wchar_t);
@@ -222,71 +231,71 @@ void Toa(long long value, StringType & res, bool clear_string = true, int base =
 	 * the size of the buffer is sufficient so the status should always be true
 	 */
 	size_t len_out;
-	Toa(value, buffer, buffer_len, base, &len_out);
+	Toa(value, buffer, buffer_len, base, &len_out, min_width);
 	res.append(buffer, len_out);
 }
 
 
 template<class StringType>
-void Toa(unsigned long value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(unsigned long value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<unsigned long long>(value), res, clear_string, base);
+	Toa(static_cast<unsigned long long>(value), res, clear_string, base, min_width);
 }
 
 
 template<class StringType>
-void Toa(long value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(long value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<long long>(value), res, clear_string, base);
+	Toa(static_cast<long long>(value), res, clear_string, base, min_width);
 }
 
 
 template<class StringType>
-void Toa(unsigned int value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(unsigned int value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<unsigned long long>(value), res, clear_string, base);
+	Toa(static_cast<unsigned long long>(value), res, clear_string, base, min_width);
 }
 
 
 template<class StringType>
-void Toa(int value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(int value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<long long>(value), res, clear_string, base);
+	Toa(static_cast<long long>(value), res, clear_string, base, min_width);
 }
 
 
 template<class StringType>
-void Toa(unsigned short value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(unsigned short value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<unsigned long long>(value), res, clear_string, base);
+	Toa(static_cast<unsigned long long>(value), res, clear_string, base, min_width);
 }
 
 
 template<class StringType>
-void Toa(short value, StringType & res, bool clear_string = true, int base = 10)
+void Toa(short value, StringType & res, bool clear_string = true, int base = 10, size_t min_width = 0)
 {
-	Toa(static_cast<long long>(value), res, clear_string, base);
+	Toa(static_cast<long long>(value), res, clear_string, base, min_width);
 }
 
 
 
-std::string to_str(unsigned long long value, int base = 10);
-std::string to_str(long long value, int base = 10);
-std::string to_str(unsigned long value, int base = 10);
-std::string to_str(long value, int base = 10);
-std::string to_str(unsigned int value, int base = 10);
-std::string to_str(int value, int base = 10);
-std::string to_str(unsigned short value, int base = 10);
-std::string to_str(short value, int base = 10);
+std::string to_str(unsigned long long value, int base = 10, size_t min_width = 0);
+std::string to_str(long long value, int base = 10, size_t min_width = 0);
+std::string to_str(unsigned long value, int base = 10, size_t min_width = 0);
+std::string to_str(long value, int base = 10, size_t min_width = 0);
+std::string to_str(unsigned int value, int base = 10, size_t min_width = 0);
+std::string to_str(int value, int base = 10, size_t min_width = 0);
+std::string to_str(unsigned short value, int base = 10, size_t min_width = 0);
+std::string to_str(short value, int base = 10, size_t min_width = 0);
 
-std::wstring to_wstr(unsigned long long value, int base = 10);
-std::wstring to_wstr(long long value, int base = 10);
-std::wstring to_wstr(unsigned long value, int base = 10);
-std::wstring to_wstr(long value, int base = 10);
-std::wstring to_wstr(unsigned int value, int base = 10);
-std::wstring to_wstr(int value, int base = 10);
-std::wstring to_wstr(unsigned short value, int base = 10);
-std::wstring to_wstr(short value, int base = 10);
+std::wstring to_wstr(unsigned long long value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(long long value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(unsigned long value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(long value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(unsigned int value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(int value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(unsigned short value, int base = 10, size_t min_width = 0);
+std::wstring to_wstr(short value, int base = 10, size_t min_width = 0);