String processing in C++ using string library

[1] String library in C++ library.
[2] Get decimalhttp://www.blogger.com/img/blank.gif value from string.
[3] iStringStream Class in C++ library.
[4] iStringStream operator.
[5] Print hex value in C++
[6] IP address validation using GNU C++ library.
[7]String to number and vice versa in C++/C Lib.



IP ADDRESS VALIDATION [6]
-------------------------
inet_ntop(), inet_pton().

//------------------------------------------------------



// IPv4 demo of inet_ntop() and inet_pton()



struct sockaddr_in sa;

char str[INET_ADDRSTRLEN];



// store this IP address in sa:

inet_pton(AF_INET, "192.0.2.33", &(sa.sin_addr));



// now get it back and print it

inet_ntop(AF_INET, &(sa.sin_addr), str, INET_ADDRSTRLEN);



printf("%s\n", str); // prints "192.0.2.33"





//-----------------------------



// IPv6 demo of inet_ntop() and inet_pton()

// (basically the same except with a bunch of 6s thrown around)



struct sockaddr_in6 sa;

char str[INET6_ADDRSTRLEN];



// store this IP address in sa:

inet_pton(AF_INET6, "2001:db8:8714:3a90::12", &(sa.sin6_addr));



// now get it back and print it

inet_ntop(AF_INET6, &(sa.sin6_addr), str, INET6_ADDRSTRLEN);



printf("%s\n", str); // prints "2001:db8:8714:3a90::12"





//--------------------------------------------------------



// Helper function you can use:



//Convert a struct sockaddr address to a string, IPv4 and IPv6:



char *get_ip_str(const struct sockaddr *sa, char *s, size_t maxlen)

{

    switch(sa->sa_family) {

        case AF_INET:

            inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr),

                    s, maxlen);

            break;



        case AF_INET6:

            inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr),

                    s, maxlen);

            break;



        default:

            strncpy(s, "Unknown AF", maxlen);

            return NULL;

    }



    return s;

}

STRING PROCESSING IN C 'atoi','atof','sscanf' [2]
--------------------------
The old C way (deprecated):

const char* str_int = "777";

const char* str_float = "333.3";

int i = atoi(str_int);

float f = atof(str_float);

A better way:

const char* str_int = "777";

const char* str_float = "333.3";

int i;

float f;



if(EOF == sscanf(str_int, "%d", &i))

{

  //error

}



if(EOF == sscanf(str_float, "%f", &f))

{

  //error

}

STRING PROCESSING IN C++ USING 'istringstream' CLASS[2][3]
--------------------------

#include 

#include 

#include 



template 

bool from_string(T& t, 

                 const std::string& s, 

                 std::ios_base& (*f)(std::ios_base&))

{

  std::istringstream iss(s);

  return !(iss >> f >> t).fail();

}



int main()

{

  int i;

  float f;

  

  // the third parameter of from_string() should be 

  // one of std::hex, std::dec or std::oct

  if(from_string(i, std::string("ff"), std::hex))

  {

    std::cout << i << std::endl;

  }

  else

  {

    std::cout << "from_string failed" << std::endl;

  }

  

  if(from_string(f, std::string("123.456"), std::dec))

  {

    std::cout << f << std::endl;

  }

  else

  {

    std::cout << "from_string failed" << std::endl;

  }

  return 0;

} 



/* output:

255

123.456

*/

STRING PROCESSING IN C++ BUILDER
-----------------------------------

//Text.SubString(1,2).c_str()

sprintf(lcTemp, "%s", Pan1Edit2PacMac->Text.SubString(1,2).c_str());



//Text.ToInt()

lsPacHwRev.HwRevChkSum=Pan1Edit4NewHwRev->Text.ToInt()+0xFF;



//AnsiString::IntToHex(addr,2)

  Memo1ScreenPrint->Lines->Add("Mac Address Retrieved from PAC: "+

   AnsiString(SPACPacketPtr->Source));

  Memo1ScreenPrint->Lines->Add(AnsiString::IntToHex(ptrlsPacMacAddr->macAddr1,2)+

   "-"+AnsiString::IntToHex(ptrlsPacMacAddr->macAddr2,2)+

   "-"+AnsiString::IntToHex(ptrlsPacMacAddr->macAddr3,2)+

   "-"+AnsiString::IntToHex(ptrlsPacMacAddr->macAddr4,2)+

   "-"+AnsiString::IntToHex(ptrlsPacMacAddr->macAddr5,2)+

   "-"+AnsiString::IntToHex(ptrlsPacMacAddr->macAddr6,2));

  Memo1ScreenPrint->Lines->Add(" at: "+AnsiString(asctime(tblock)));



//AnsiString(text).AnsiPos("KeyWords")

  lcTemp=AnsiString(lsStringBuffer).AnsiPos("OK");

  if (lcTemp==0)

   lcTemp=AnsiString(lsStringBuffer).AnsiPos("0");

//validate and decode ip address string

#include sys/types.h

#include sys/socket.h

#include arpa/inet.h







//To validate and decode ip address

std::string str3="";

size_t pos,posLast;

struct sockaddr_in sa;

char str[INET_ADDRSTRLEN];

int liRet;





//Check whether it's valid IP address

liRet=inet_pton(AF_INET,pszVal,&(sa.sin_addr));

if(liRet<0){

	std::cout<<"Error: Only IpV4 address is supported"<}else if(liRet==0){

	std::cout<<"Illegal IpV4 address string"<}else{

	inet_ntop(AF_INET,&(sa.sin_addr),str,INET_ADDRSTRLEN);

	std::cout<}





posLast=0;

pos=0;

//for(int j=0;j<4;j++){

//	pos = std::string(pszVal).find(".",pos);    // position of "." in str

//	str3 = std::string(pszVal).substr (posLast,pos-posLast);   // get from f"live" to the end

//	from_string(lRealValue, str3, std::dec);

//	std::cout<<"part "<//	posLast=pos+1;

//	pos++;

}