Use using using instead of typedef__c++ in c++11

Example 1:

void F () {} 
int main ()
{
    using functionptr = void (*) ();///equivalent to typedef void (*FUNCTIONPTR) ();
 
    FunctionPtr ptr = f;
}

Example 2:
typedef unsigned char U1;
typedef unsigned short U2;


Using U4 = uint32_t;
Using U8 = uint64_t;


Example 3:
Using Line_no = std::vector<string>::size_type;
Equivalent to: typedef vector<string>::size_type LINE_NO;


Example 4:
typedef std::unique_ptr<std::unordered_map<std::string, std::string>> UPTRMAPSS;
Using UPTRMAPSS = std::unique_ptr<std::unordered_map<std::string, std::string>>;
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