int stringLength = stringToSearch.length();

int periodCounter = 0;

int periodPosition = -1;

int i = 0;

for (i = 0; i < stringLength; ++i) {

if (stringToSearch[i] == '.') {

++periodCounter;

periodPosition = i;

}

}

// If there are zero or two or more periods, indicate an incorrect domain name

// by setting variable periodPosition to -1

if (periodCounter != 1) {

periodPosition = -1;

}

return periodPosition;

const int MAX_SECONDLEVEL_LENGTH = 63;

const char DASH = '-';

bool isValidSecondLevel = true; // Assume valid second-level domain

int secondLevelLength = secondLevel.length();

char nextChar = '?';

int i = 0;

// Disqualify the second-level domain if it is too short or too long, or

// if it begins or ends with a dash

if ((secondLevelLength >= 1) &&

(secondLevelLength <= MAX_SECONDLEVEL_LENGTH)) {

if ((secondLevel[0] == DASH) ||

(secondLevel[secondLevelLength - 1] == DASH)) {

isValidSecondLevel = false;

}

}

else {

isValidSecondLevel = false;

}

// Disqualify the second-level domain if any character is not a letter,

// digit, or a dash

i = 0;

while ((i < secondLevelLength) && (isValidSecondLevel)) {

nextChar = secondLevel[i];

if ((!isalnum(nextChar)) && (nextChar != DASH)) {

isValidSecondLevel = false;

}

++i;

}

return isValidSecondLevel;

bool isValidTopLevel = true; // Assume valid top-level domain

int topLevelLength = theTld.length();

char nextChar = '?';

int i = 0;

// Disqualify the top-level domain if it is the empty string or

// the first character is not a period

if ((topLevelLength <= 0) || (theTld[0] != '.')) {

isValidTopLevel = false;

}

// Disqualify the top-level domain if any character is not a letter or a digit

i = 1;

while ((i < topLevelLength) && (isValidTopLevel)) {

nextChar = theTld[i];

if (!isalnum(nextChar)) {

isValidTopLevel = false;

}

++i;

}

return isValidTopLevel;

bool isSpecial = false;

int i = 0;

i = 0;

while ((i < MAX_NUMS) && (!isSpecial)) {

if (specialGtld[i] == tld) {

isSpecial = true;

}

else {

++i;

}

}

return isSpecial;

string userInput = "";

cout << prompt << endl;

cin >> userInput;

return userInput;

const string PROMPT_DOMAIN_NAME = "\nEnter the next domain name (Enter to exit): ";

// Define the list of valid core gTLDs and restricted gTLDs

vector<string> validCoreGtld(MAX_NUMS);

vector<string> validRestrictedGtld(MAX_NUMS);

string inputName = "";

string searchName = "";

string secondLevel = ""; // In aaa.bbb, the aaa part, aka second-level domain

string theTld = ""; // In aaa.bbb, the bbb part, aka top-level domain

int periodPosition = 0;

bool isCoreGtld = false;

bool isPeriodPositionValid = false;

bool isRestrictedGtld = false;

bool isDomainValid = false;

int i = 0;

validCoreGtld.at(0) = ".com";

validCoreGtld.at(1) = ".net";

validCoreGtld.at(2) = ".org";

validCoreGtld.at(3) = ".info";

validRestrictedGtld.at(0) = ".biz";

validRestrictedGtld.at(1) = ".name";

validRestrictedGtld.at(2) = ".pro";

inputName = GetString(PROMPT_DOMAIN_NAME);

while (inputName.length() > 0) {

searchName = inputName;

for (i = 0; i < inputName.length(); ++i) {

searchName[i] = tolower(inputName[i]);

}

isCoreGtld = false;

isDomainValid = false;

periodPosition = GetPeriodPosition(searchName);

isPeriodPositionValid = (periodPosition >= 1);

// The domain name is valid if there is exactly one period in the

// domain name (at location periodPosition) and the domain name does

// not start or end with a period. Note that a period position of 0 means

// the first character is a period, rendering the domain name invalid

if ((periodPosition > 0) && (searchName[searchName.length() - 1] != '.')) {

isPeriodPositionValid = true;

}

else {

isPeriodPositionValid = false;

}

if (isPeriodPositionValid) {

// Extract the second-level domain and the top-level domain

secondLevel = searchName.substr(0, periodPosition);

theTld = searchName.substr(periodPosition);

isDomainValid = HasValidSecondLevel(secondLevel) && HasValidTld(theTld);

// If the domain name is valid see if there is a core gTLD or a restricted gTLD

if (isDomainValid) {

isCoreGtld = IsSpecialGtld(validCoreGtld, theTld);

if (!isCoreGtld) {

isRestrictedGtld = IsSpecialGtld(validRestrictedGtld, theTld);

}

}

}

// Display the results

cout << "\"" << inputName << "\" ";

if (isDomainValid) {

cout << "is a valid domain name and ";

if (isCoreGtld) {

cout << "has a core gTLD of \"" << theTld << "\"." << endl;

}

else if (isRestrictedGtld) {

cout << "has a restricted gTLD of \"" << theTld << "\"." << endl;

}

else {

cout << "has a TLD of \"" << theTld << "\"." << endl;

}

}

else {

cout << "is not a valid domain name." << endl;

}

inputName = GetString(PROMPT_DOMAIN_NAME);

}

return 0;

}