> For the complete documentation index, see [llms.txt](https://mr-poston-1.gitbook.io/c++/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mr-poston-1.gitbook.io/c++/2.-going-beyond-the-basics/2.4-file-input-output/2.4.3-processing-a-file.md).

# 2.4.3 Processing a File

As you saw in the previous example, you can read in a file line by line in a `while` loop.

```
string line;
while (true) {
    getline(in, line);  
    if (in.fail()) break;

    // process line
}
```

Each time through the loop, the `line` variable gets updated with the next line. Once you loop again, the previous line is lost, so you need to process that line in the loop.

### Basic Line Processing

The simplest way to deal with the line in the loop is to add it to a string vector. By creating the vector before the loop and adding the line to the vector, you will end up with a vector with all the lines after the loop.

```
string line;
vector<string> input;
while (true) {
    getline(in, line);  
    if (in.fail()) break;

    input.push_back(line);
}
```

This method can be considered a basic line process since you will most likely need to do something with each line after your input loop.

### Detailed Line Processing

Since you are already looping through all the lines, it may be more convenient to break down a line further as you are looping.

In this example, you will see how this can be processed and printed as you read in the data.

### [Try This Example](https://replit.com/@Poston/243-Processing-a-File#main.cpp)