document fix

README.md

@@ -11,13 +11,13 @@ Use `SN_NUMBER foo(str)` to declare a scientific number class,use `foo.SN_Produc
 scientific notation digits string.
 
 ## Example
-<pre>
+```cpp
 std::string NumStr = "1024.96";
 SN_NUMBER MyNum1(NumStr), MyNum2("123456");
 std::cout << "MyNum1:" << MyNum1 << std::endl;
 std::cout << "MyNum2:" << MyNum2 <<"Number of digits: "<< MyNum2.NDIGIT() << std::endl;
 SN_NUMBER MyNum3("12a3445");
-</pre>
+```
 
 *The Outputs would be:*
  <pre>
@@ -28,22 +28,40 @@ Error info: Some of the inputs is not digit.
 
 
 
-# Functions
-Functions declared are listed by:
-+ **SN_NUMBER(std:: string SN_NUMSTR, NTYPE type)**
+# Document
+Class' inside functions declared are listed by:
+```cpp
+SN_NUMBER(std:: string SN_NUMSTR, NTYPE type)
+```
+Construct a SN_NUMBER class using string,differs the explaination type.
 
-Construct a SN_NUMBER class using string,differs the explaination type using the SN_NUMBER::NTYPE_ vars;
+The default type is SN_NUMBER::NTYPE_EXP,which looks like:
+```js
+1.345789E3
+```
 
-+ **DOTP()**
+For example:
+```cpp
+SN_NUMBER("3145.92657");
+SN_NUMBER(str,SN_NUMBER::NTYPE_TENS);
+SN_NUMBER("3145.92657",SN_NUMBER::NTYPE_EXP);
+```
 
-Rturns an interger that shows the dot's position in the former number.
 
-+ **NDIGIT()**
+```cpp
+DOTP()
+```
 
-Returns an interger that shows the length of number.
+Rturns an interger that shows the dot's position in the former number
+```cpp
+NDIGIT()
+```
 
-+ **DIGIT()** 
+Returns an interger that shows the length of number.
 
+```cpp
+DIGIT()
+```
 Returns an interger that shows the digits of former number's interger part.
 # Support
 Get easy to create issues if you find a bug,pull requests are welcomed.