Need help with c++ - beginning programmer?

so i have a program that reads in a file and decodes the file then spits out the message. the symbol @ followed by an int will declare what amount i need to shift the alphabet by. i have all of that working fine. my problem is if there isn't an int following the symbol, the program displays an error i made. i need it to discard the rest of the message until it reaches the # symbol. when it reaches that, it will start behaving like normal again. i would appreciate any help.

Need help with c++ - beginning programmer?
if @n occurs on a line by itself, where n is a number or invalid character.


Read the line in.


Call atoi on the string after @.


if atoi returns 0, assume invalid number entered then read characters until the character '#' is encountered.





do {


infile.getline(buffer, 80);


if (*buffer == '@') // if first character = '@'


{


shift = atoi(buffer + 1); // process characters after '@'


if (!shift %26amp;%26amp; errno == ERANGE) // atoi sets errno on invalid value


{


while (!infile.eof() %26amp;%26amp; infile.get() != '#');


continue; // processing file.


}


}


} while (!infile.eof());
Reply:you need to determine if there character after the @ is a digit.


if it is not a digit you have an error, and should read characters until you reach an # or an end of stream.





where exactly is the problem ?


is it the transformation from characters to int ?