Try/Catch/Throw...Can't get data read in right, and stuck in an infinite loop!

[aemado]

I am trying to read in several lines, each should have exactly 5 pieces of data. I am using try/catch/throw to determine if the data is in the correct format, and trying to use iss to separate the parts. However, this is my first time using both, and I am pretty certain that I am missing something obvious. Firstly, by debugging, I found that the first piece of data is being checked in the second case, giving me errors. I believe I may need to read in more from the iss>> than just the one, but I am lost. Any suggestions?? Here is my code:

    ifstream indata;
    ifstream indata2;
    string instring;
    string instring2;
    istringstream iss_string;
    istringstream iss_string2;
    string data[5];
    string data2[5];
    int count = 0;
    int count2 = 0;
    int datacount = 0;
    int offset;
    int offset2;
 
    indata.open("student.data");
    if(!indata){
        cout<<"student.data file could not be opened.";
        exit(1);}
 
    while(indata){
        getline(indata, instring);
 
        try{
            while(instring != "0"){
                iss_string.str(instring);
                iss_string >> data[count];
                datacount++;
                offset = iss_string.tellg();
                while(offset >= 0){
                    switch(count){
                        case 0:
                            if(data[count].length() != 9){
                                throw 0;
                                break;
                            }
                            for(int i=0; i < (data[count].length()); i++){
                                if(!isdigit(data[count][i])){
                                    throw 0;
                                    break;
                                }
                            }
                        case 1:
                            if(data[count].length() > 30 || data[count].length() < 1){
                                throw string("Invalid number of characters in Last Name of student.data file");
                                break;
                            }
                            for(int i=0; i<data[count].length(); i++){
                                if(!isalpha(data[count][i])){
                                    throw string("Invalid characters in Last Name of student.data file");
                                    break;
                                }
                            }
 
                        case 2:
                            if(data[count].length() > 30 || data[count].length() < 1){
                                throw string("Invalid number of characters in First Name of student.data file");
                                break;
                            }
                            for(int i=0; i<data[count].length(); i++){
                                if(!isalpha(data[count][i])){
                                    throw string("Invalid characters in First Name of student.data file");
                                }
                            }
 
                        case 3: 
                            if(data[count].length() != 2){
                                throw string("Invalid number of characters in Major of student.data file");
                                break;
                            }
                            for(int i=0; i<data[count].length(); i++){
                                if(!isalpha(data[count][i])){
                                    throw string("Invalid characters in Major of student.data file");
                                }
                            }
 
                        case 4: 
                            if(data[count].length() != 2){
                                throw string("Invalid number of characters in Year of student.data file");
                            }
                            for(int i=0; i<data[count].length(); i++){
                                if(!isalpha(data[count][i])){
                                    throw string("Invalid characters in Year of student.data file");
                                }
                            }
                            //break;
                    }
 
                }
            }
 
            count++;
            iss_string>>data[count];
            offset = iss_string.tellg();
            if(datacount != 5){
                throw string("Invalid number of items in line of student.data.");
 
                //break;
            }
            getline(indata, instring);
            iss_string.clear();
            count = 0;
        }
        catch(int x){
            cout<<"Invalid ID number in student.data file";
            exit(1);
        }
        catch(string s){
            cout<< s <<endl;
            exit(1);
        }
    }
    indata.close();
 

[weaknessforcats]

Start by reducing the size of your try block.

A try block should cover one or may be two statements.

Also, a parser is built using a finite-state automaton and not a giant switch staement. You might read: http://bytes.com/forum/thread660060.html.