ASP.NET PDF Viewer using C#, VB/NET

what you want to do with the file. This becomes important later when you write to files or create new ones from scratch. For opening and reading files, and appear identical, but they have different uses. can accept a code block, and once the block is finished, the file will be closed automatically. However, only returns a File object referring to the file. To close the file, you have to use its close method. Let s compare the two methods. First, look at

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FIGURE 9-17 Presenting your methodology and data first before your recommendations quickly overwhelms working memory.

This code opens text.txt and then passes the file handle into the code block as f. puts f.gets takes a line of data from the file and prints it to the screen. Now, have a look at the approach:

In this example, a file handle/object is assigned to f directly. You close the file handle manually with the close method at the end. Both the code block and file handle techniques have their uses. Using a code block is a clean way to open a single file quickly and perform operations in a single location. However, assigning the File object with makes the file reference available throughout the entire current scope without needing to contain file manipulation code within a single block.


So, your function gets a set of values in through its parameters. Can you change them And what happens if you do Well, the parameters are just variables like all others, so this works as you would expect. Assigning a new value to a parameter inside a function won t change the outside world at all: >>> def try_to_change(n): n = 'Mr. Gumby' >>> name = 'Mrs. Entity' >>> try_to_change(name) >>> name 'Mrs. Entity' Inside try_to_change, the parameter n gets a new value, but as you can see, that doesn t affect the variable name. After all, it s a completely different variable. It s just as if you did something like this: >>> name = 'Mrs. Entity' >>> n = name # This is almost what happens when passing a parameter >>> n = 'Mr. Gumby' # This is done inside the function >>> name 'Mrs. Entity' Here, the result is obvious. While the variable n is changed, the variable name is not. Similarly, when you rebind (assign to) a parameter inside a function, variables outside the function will not be affected.

Note You might need to specify the location of files directly, as text.txt might not appear to be in the

current directory. Simply replace f ="text.txt", "r") with f ="c:\full\ path\here\text.txt", "r"), including the full path as necessary. Alternatively, use the result of Dir::pwd to see what the current working directory is and put text.txt there.

A symptom that overwhelm has happened in your presentation is if your client asks you to skip ahead to the end, or asks you to get to the point which indicates that you didn t get to the point in the rst place. Journalists call this ineffective structural approach burying the lead, because you put the most important information somewhere else other than at the top level of attention of your audience. The good news is that you likely don t have to create new information for your presentation you just have to restructure what you have using the story template to ensure that you present the most important information to the audience s working memory rst. None of this is to say that you will not present detailed data or complex charts when you present the Explanation and Detail (Methodology/Data) slides. If your clients have prior knowledge of complex data structures, the slides can include those elements without overwhelming working memory because the understanding of the structure of this information is already held in the audience s long-term memory. If the source of the data is important to have available for detailed discussion, provide that on paper or in an electronic document to accompany the presentation.

You could also choose to assign the file handle to a class or instance variable:

class MyFile attr_reader :handle def initialize(filename) @handle =, "r") end def finished @handle.close end end f ="text.txt") puts f.handle.gets f.finished

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