我编写了一个程序，在一个包含许多有效和无效电子邮件的文本文件中查找有效的电子邮件地址。
& 然后在另一个文本文件中输出有效的电子邮件。
我遇到的问题是创建一个子字符串或对象，它将读取@符号左侧的行，如果有多个“。”，则读取为真。
例如：将这行文本作为有效的电子邮件阅读 - Jimmy.Cole@yahoo.com
&
如果有更多的“。” @ 符号后读为假。这是我的代码：
#include<iostream>
#include<string>
#include<fstream>
using namespace std;
const string DEFAULT_INPUT_FILENAME="fileContainingEmails.txt";
const string DEFAULT_OUTPUT_FILENAME="copyPasteMyEmails.txt";
const int N=1000; //assuming atmost 1000 email
//function prototypes
bool isNotDuplicateEmail(string emails[], int emailCount, string emailTemp);
bool isValidEmail(string emails[], string emailTemp);
void WriteToFile(string emails[], int emailCount, string outputFile);
void DisplayEmailsToConsole(string emails[], int emailCount);
bool isValidEmailChar(char c);
int countOccurenceOfAt(string emailTemp);
int countOccurenceOfDot(string emailTemp);
int main()
{
//variable declaration
ifstream fin;
string inputFile;
string outputFile;
int emailCount=0;
string emails[N];
//ask user for input and output file name
cout<<"Enter input file name: ";
getline(cin,inputFile);
cout<<"Enter output file name: ";
getline(cin,outputFile);
//check for default names
if(inputFile=="")
inputFile=DEFAULT_INPUT_FILENAME;
if(outputFile=="")
outputFile=DEFAULT_OUTPUT_FILENAME;
cout<<"Input File Name = "<<inputFile<<endl;
cout<<"Output File Name = "<<outputFile<<endl;
//open input file
fin.open(inputFile.c_str());
//if file does not exists, display error message and return
if(!fin)
{
cout<<"ERROR: "<<inputFile<<" doen not exists."<<endl;
return 1;
}
string emailTemp;
/*read each line from file, and if it is not a duplicate email and a valid email
then add it to email list and increment count*/
while(getline(fin,emailTemp))
{
if(isNotDuplicateEmail(emails,emailCount,emailTemp) && isValidEmail(emails,emailTemp))
{
emails[emailCount]=emailTemp;
emailCount++;
}
}
//close input file
fin.close();
//call function to write emails to output file and console
if(emailCount>0)
{
WriteToFile(emails, emailCount, outputFile);
cout << endl << emailCount << " email addresses were found, and copied to the file " << outputFile<<endl;
DisplayEmailsToConsole(emails, emailCount);
}
else
{
cout << "Sorry, no email addresses were found in the file " << inputFile << endl;
}
cout << endl<< "Press ENTER to continue..." << endl;
cin.get();
return 0;
}
bool isNotDuplicateEmail(string emails[], int emailCount, string emailTemp)
{
/*Check each email address and if a duplicate email is found, return false*/
/*If email is not a duplicate email, return true*/
for(int i=0;i<emailCount;i++)
{
if(emailTemp==emails[i])
return false;
}
return true;
}
bool isValidEmail(string emails[], string emailTemp)
{
if(emailTemp=="")
return false;
/*If there are more than 1 @*/
if (countOccurenceOfAt(emailTemp)!=1)
return false;
/*If there are more than 1 .*/
if(countOccurenceOfDot(emailTemp)!=1)
return false;
int index1=-1;
int index2=-1;
//check each character for valid email char
for (int i=0; i<emailTemp.size(); i++)
{
if(!isValidEmailChar(emailTemp[i]))
return false;
}
//find index of @ and .
index1=emailTemp.find_first_of('@');
index2=emailTemp.find_first_of('.');
if(index1<1)
return false;
if(index2<index1)
return false;
if((index2-index1)==1)
return false;
if(((emailTemp.size()-1)-index2)==0)
return false;
return true;
}
bool isValidEmailChar(char c)
{
/* check for valid email characters 0-9, @, ., A-Z, a-z, _, +, - */
if(c>='0' && c<='9')
return true;
if(c>='A' && c<='Z')
return true;
if(c>='a' && c<='z')
return true;
if(c=='@' || c=='.' || c=='_' || c=='+' || c=='-')
return true;
return false;
}
/*Function to count occurence of @ in email address*/
int countOccurenceOfAt(string emailTemp)
{
int count=0;
for(int i=0;i<emailTemp.size();i++)
{
if(emailTemp[i]=='@')
count++;
}
return count;
}
/*Function to count occurence of . in email address*/
int countOccurenceOfDot(string emailTemp)
{
int count=0;
for(int i=0;i<emailTemp.size();i++)
{
if(emailTemp[i]=='.')
count++;
}
return count;
}
void DisplayEmailsToConsole(string emails[], int emailCount)
{
/*Display console message and then display each email address, one at a line*/
cout << endl << endl << "You can open the output file and copy/paste its contents into the \"to\", \"cc\", or \"bcc\" field of any email message. It is best to use the \"bcc\" field so that everyone's email address does not appear in the message, to protect their privacy"<<endl;
cout << endl << "Email List is: "<< endl;
for (int i=0; i<emailCount; i++)
{
cout << emails[i] << endl;
cout << endl;
}
}
void WriteToFile(string emails[], int emailCount, string outputFile)
{
/*Open file and write each email address to output file followed by ; */
ofstream fout;
fout.open(outputFile.c_str());
for(int i=0; i<emailCount; i++)
{
fout << emails[i] << "; " << endl;
}
//close file
fout.close();
}