count the frequency of each letter of the alphabet in a file

[svd]

so i'm attempting to make a program that reads in a file and then counts the frequency of each letter of the alphabet in the file and then outputs the letter with the frequency into a different file..
i didn't include the first part of the program because i'm pretty sure it's correct... i really have no clue what's wrong with this so any help would be great

    vector<int> occurrencesVec(26);
    int i;
    for(;;)
    {
        fin >> i;
        if (fin.eof()) break;
        else
        {
        if (('A'<=i<='Z') || ('a'<=i<='z'))
        {
            char lowercase = tolower(i);
            occurrencesVec[lowercase - 'a']++;
        }
        }
    }
    for (int i = 1; i < occurrencesVec.size(); i++)
    {
        fout <<  i << occurrencesVec[i];
    }
}
 

[Ganon11]

1) Why are you reading in to an integer if there are going to be characters? Try making i a char.

2) Are there words in this file, or just letters separated by whitespace? If there are words, you may want to try fin.get rather than the >> operator.

Other than these minor things, your code looks fine. What exactly is not working?

[svd]

1) Why are you reading in to an integer if there are going to be characters? Try making i a char.

2) Are there words in this file, or just letters separated by whitespace? If there are words, you may want to try fin.get rather than the >> operator.

Other than these minor things, your code looks fine. What exactly is not working?

the file is just a bunch of words seperated by whitespaces, so i changed the fin >> i; to fin.get(i).. is that what you meant?

to answer your second question, the program builds fine, but when I "start without debugging" after I enter the infile name and the outfile name, a pop-up comes up that says "Debug assertion failed... vector subscript out of range"

it still does this after changing the >>

[weaknessforcats]

file is just a bunch of words seperated by whitespaces, so i changed the fin >> i; to fin.get(i).. is that what you meant?

to answer your second question, the program builds fine, but when I "start without debugging" after I enter the infile name and the outfile name, a pop-up comes up that says "Debug assertion failed... vector subscript out of range"

it still does this after changing the >>

The >> operator cannot be used for strings. It skips whitespace so all you get is one word of the string. If that's your situation, then you are OK. Otherwise, use cin.getline() to fetch multiple word strings.

The debug assertion failure is almost certainly using the vector operator[] with an invalid index number. The only values you can use are the ones between 0 and size()-1 of the vector. Is this a case of an uninitialized index??

[svd]

The >> operator cannot be used for strings. It skips whitespace so all you get is one word of the string. If that's your situation, then you are OK. Otherwise, use cin.getline() to fetch multiple word strings.

The debug assertion failure is almost certainly using the vector operator[] with an invalid index number. The only values you can use are the ones between 0 and size()-1 of the vector. Is this a case of an uninitialized index??

what does uninitialized index mean? i'm trying to look at all the letters individually in the paragraph and put the frequency for each letter into a vector

[weaknessforcats]

If you are using:

vector<int>  data;
 
cout << data[256];    //ERROR. There is no element 256
 

Usually, the 256 is the value of a variable:

vector<int>  data;
 
cout << data[i];    //ERROR. 
 

and the i has a bad value.

For arrays, the value between the [] is called the index value.