String shrinking and Autonumber

In a program I am currently creating, users are saved into a file. Is it possible to set it so that a user is automaticly given a membership number in the format XXX, but there has to be three numbers. So user 1 would be, 001.

Also can you shrink a string. So if I have declared a string as string[30], but the user puts in a filename, such as file.txt, can I remove the .txt extension from the string.

Originally posted by Necrodeemer
In a program I am currently creating, users are saved into a file. Is it possible to set it so that a user is automaticly given a membership number in the format XXX, but there has to be three numbers. So user 1 would be, 001.

Also can you shrink a string. So if I have declared a string as string[30], but the user puts in a filename, such as file.txt, can I remove the .txt extension from the string.

For the second part you can make a new pointer where you store the name withought the .txt and then you delete the first pointer that has the name and the .txt

This is what I understood for the first part, do you have anything about the second part?

keep track of last user number issued. Increment by one for each new one issued. Store user number as a string using itoa() or sprintf() or strstream or whatever. Determine string length. If length 1 append two zero's. If length is two append 1 zero.

Code:

int lastUserNumber = 0;
char continue = 'y';
int currentUserNumber;
char sUserNumber[4];
int length;
char twoZeros[4] = "00";
char oneZero[4] = "0";
char tempStr[4];

while(continue)
{
   //new user number
   currentUserNumber = ++lastUserNumber;
   sprintf(sUserNumber, "%d", currentUserNumber);//or whatever
   length = strlen(sUserNumber);
   if(length == 1)
   {
      strcpy(tempStr, twoZeros);
      strcat(tempStr, sUserNumber);
      strcpy(sUserNumber, tempStr);
   }
   else if (length == 2)
     //similar for length == 2

   //then do something with sUserNumber
   cout << "this user number is" << sUserNumber << endl;

   cout << "to stop enter any key but lower case y" << endl;
   cin >> continue;
}

There are many ways to shrink a string. One way is to copy the contents of the original string into a second one, char by char, until you find the char you want to use as a terminating char.

Code:

char filename[20];
char input[20];
cout << "enter a filename with extension:  xxxxxx.xxx" 
cin >> input;
//copy input into filename until you find a period.
int i;
for(i = 0; i < strlen(input); ++i)
{
  if(input[i] = '.')
  {
     filename[i] = '\0';
     break;
   }
  else
     filename[i] = input[i];
}