1. Using Chitubox
2. Using Commas
3. Using Countif In Excel
4. Using Chalk Paint On Furniture
5. Using Coffee Grounds In The Garden
6. Using C#

In this tutorial, you'll learn how to do file IO, text and binary, in C, using fopen, fwrite, and fread, fprintf, fscanf, fgetc and fputc. FILE. For C File I/O you need to use a FILE pointer, which will let the program keep track of the file being accessed. (You can think of it as the memory address of the file or the location of the file).

There are reasons to prefer developing Bluetooth applicationsin C instead of in a high level language such as Python. The Pythonenvironment might not be available or might not fit on the target device;strict application requirements on program size, speed, and memory usage maypreclude the use of an interpreted language like Python; the programmer maydesire finer control over the local Bluetooth adapter than PyBluez provides;or the project may be to create a shared library for other applications tolink against instead of a standalone application.As of this writing, BlueZ is a powerful Bluetooth communications stack withextensive APIs that allows a user to fully exploit all local Bluetoothresources, but it has no official documentation. Furthermore, there is verylittle unofficial documentation as well. Novice developers requestingdocumentation on the official mailing lists [1] are typicallyrebuffed and told to figure out the API by reading through the BlueZ sourcecode. This is a time consuming process that can only reveal small pieces ofinformation at a time, and is quite often enough of an obstacle to deter manypotential developers.

1. A: UVC radiation is a known disinfectant for air, water, and nonporous surfaces. UVC radiation has effectively been used for decades to reduce the spread of bacteria, such as tuberculosis.
2. Test your C# code online with.NET Fiddle code editor.
3. Note: Replace the C: RepairSource Windows placeholder with the location of your repair source. For more information about using the DISM tool to repair Windows, reference Repair a Windows Image. At the command prompt, type the following command, and then press ENTER.

This chapter presents a short introduction to developing Bluetoothapplications in C with BlueZ. The tasks covered in chapter 2 are nowexplained in greater detail here for C programmers.

A simple program that detects nearby Bluetooth devices is shown in Example 4-1. The program reserves system Bluetoothresources, scans for nearby Bluetooth devices, and then looks up the userfriendly name for each detected device. A more detailed explanation of thedata structures and functions used follows.

Example 4-1. simplescan.c

4.1.1. Compilation

To compile our program, invoke gcc and link againstlibbluetooth

# gcc -o simplescan simplescan.c -lbluetooth

4.1.2. Explanation

The basic data structure used to specify a Bluetooth device address is thebdaddr_t. All Bluetooth addresses in BlueZ will be storedand manipulated as bdaddr_t structures. BlueZ provides twoconvenience functions to convert between strings andbdaddr_t structures.

str2ba takes an string of the form ``XX:XX:XX:XX:XX:XX',where each XX is a hexadecimal number specifying an octet of the 48-bitaddress, and packs it into a 6-byte bdaddr_t.ba2str does exactly the opposite.

Local Bluetooth adapters are assigned identifying numbers starting with 0, anda program must specify which adapter to use when allocating system resources.Usually, there is only one adapter or it doesn't matter which one is used, sopassing NULL to hci_get_route willretrieve the resource number of the first available Bluetooth adapter.

It is not a good idea to hard-code the devicenumber 0, because that is not always the id of the first adapter. For example,if there were two adapters on the system and the first adapter (id 0) isdisabled, then the first available adapter is the one withid 1.

If there are multiple Bluetooth adapters present, then to choose the adapterwith address ``01:23:45:67:89:AB', pass the char * representation of the address to hci_devid and use that inplace of hci_get_route.

Most Bluetooth operations require the use of an open socket.hci_open_dev is a convenience function that opens aBluetooth socket with the specified resource number [2]. To be clear, the socket openedby hci_open_dev represents a connection to themicrocontroller on the specified local Bluetooth adapter, and not a connectionto a remote Bluetooth device. Performing low level Bluetooth operationsinvolves sending commands directly to the microcontroller with this socket, andSection 4.5 discusses this in greater detail.

After choosing the local Bluetooth adapter to use and allocating systemresources, the program is ready to scan for nearby Bluetooth devices. In theexample, hci_inquiry performs a Bluetooth device discoveryand returns a list of detected devices and some basic information about them inthe variable ii. On error, it returns -1 and setserrno accordingly.

hci_inquiry is one of the few functions that requires theuse of a resource number instead of an open socket, so we use thedev_id returned by hci_get_route. Theinquiry lasts for at most 1.28 * len seconds, and at mostmax_rsp devices will be returned in the output parameterii, which must be large enough to accommodatemax_rsp results. We suggest using amax_rsp of 255 for a standard 10.24 second inquiry.

If flags is set to IREQ_CACHE_FLUSH, thenthe cache of previously detected devices is flushed before performing thecurrent inquiry. Otherwise, if flags is set to 0, then theresults of previous inquiries may be returned, even if the devices aren't inrange anymore.

The inquiry_info structure is defined as

For the most part, only the first entry - the bdaddr field,which gives the address of the detected device - is of any use. Occasionally,there may be a use for the dev_class field, which givesinformation about the type of device detected (i.e. if it's a printer, phone,desktop computer, etc.) and is described in the Bluetooth AssignedNumbers [3]. The rest of the fields are used for lowlevel communication, and are not useful for most purposes. The interestedreader can see the Bluetooth Core Specification [4] for more details.

Once a list of nearby Bluetooth devices and their addresses has been found,the program determines the user-friendly names associated with thoseaddresses and presents them to the user. Thehci_read_remote_name function is used for this purpose.

hci_read_remote_name tries for at mosttimeout milliseconds to use the socketsock to query the user-friendly name of the device withBluetooth address ba. On success,hci_read_remote_name returns 0 and copies at most the firstlen bytes of the device's user-friendly name intoname. On failure, it returns -1 and setserrno accordingly.

Notes[1]

Using Chitubox

http://www.bluez.org/lists.html

[2]

for thecurious, it makes a call to socket(AF_BLUETOOTH, SOCK_RAW,BTPROTO_HCI), followed by a call to bind with thespecified resource number.

[3]

https://www.bluetooth.org/foundry/assignnumb/document/baseband

[4]

http://www.bluetooth.org/spec

Using Commas

In this tutorial, you'll learn how to do file IO, text and binary, in C, using fopen, fwrite, and fread, fprintf, fscanf, fgetc and fputc.

FILE *

For C File I/O you need to use a FILE pointer, which will let the programkeep track of the file being accessed. (You can think of it as the memoryaddress of the file or the location of the file).

For example:

fopen

Using Countif In Excel

To open a file you need to use the fopen function, which returns a FILE pointer. Once you've opened a file, you can use the FILE pointer to let the compiler perform input and output functions on the file.
In the filename, if you use a string literal as the argument, you need to remember to use double backslashes rather than a single backslash as you otherwise risk an escape character such as t. Using double backslashes escapes the key, so the string works as it is expected. Your users, of course, do not need to do this! It's just the way quoted strings are handled in C and C++.

fopen modes

The allowed modes for fopen are as follows: Note that it's possible for fopen to fail even if your program is perfectly correct: you might try to open a file specified by the user, and that file might not exist (or it might be write-protected). In those cases, fopen will return 0, the NULL pointer.
Here's a simple example of using fopen:
This code will open test.txt for reading in text mode. To open a file in a binary mode you must add a b to the end of the mode string; for example, 'rb' (for the reading and writing modes, you can add the b either after the plus sign - 'r+b' - or before - 'rb+')

fclose

When you're done working with a file, you should close it using the function
fclose returns zero if the file is closed successfully.
An example of fclose is

Reading and writing with fprintf, fscanf fputc, and fgetc

To work with text input and output, you use fprintf and fscanf, both of which are similar to their friends printf and scanf except that you must pass the FILE pointer as first argument. For example:
It is also possible to read (or write) a single character at a time--this canbe useful if you wish to perform character-by-character input (for instance,if you need to keep track of every piece of punctuation in a file it wouldmake more sense to read in a single character than to read in a string at atime.) The fgetc function, which takes a file pointer, and returns an int,will let you read a single character from a file:Notice that fgetc returns an int. What this actually means is that when itreads a normal character in the file, it will return a value suitable forstoring in an unsigned char (basically, a number in the range 0 to 255). Onthe other hand, when you're at the very end of the file, you can't get acharacter value--in this case, fgetc will return 'EOF', which is a constant thatindicates that you've reached the end of the file. To see a full exampleusing fgetc in practice, take a look at the example here.
The fputc function allows you to write a character at a time--you might findthis useful if you wanted to copy a file character by character. It lookslike this:Note that the first argument should be in the range of an unsigned char sothat it is a valid character. The second argument is the file to write to.On success, fputc will return the value c, and on failure, it will return EOF.

Binary file I/O - fread and fwrite

For binary File I/O you use fread and fwrite.
The declarations for each are similar: Both of these functions deal with blocks of memories - usually arrays. Because they accept pointers, you can also use these functions with other data structures; you can even write structs to a file or a read struct into memory.
Let's look at one function to see how the notation works.
fread takes four arguments. Don't be confused by the declaration of a void *ptr; void means that it is a pointer that can be used for any type variable. The first argument is the name of the array or the address of the structure you want to write to the file. The second argument is the size of each element of the array; it is in bytes. For example, if you have an array of characters, you would want to read it in one byte chunks, so size_of_elements is one. You can use the sizeof operator to get the size of the various datatypes; for example, if you have a variable int x; you can get the size of x with sizeof(x);. This usage works even for structs or arrays. E.g., if you have a variable of a struct type with the name a_struct, you can use sizeof(a_struct) to find out how much memory it is taking up.
e.g.,
The third argument is simply how many elements you want to read or write; for example, if you pass a 100 element array, you want to read no more than 100 elements, so you pass in 100.
The final argument is simply the file pointer we've been using. When fread is used, after being passed an array, fread will read from the file until it has filled the array, and it will return the number of elements actually read. If the file, for example, is only 30 bytes, but you try to read 100 bytes, it will return that it read 30 bytes. To check to ensure the end of file was reached, use the feof function, which accepts a FILE pointer and returns true if the end of the file has been reached.
fwrite is similar in usage, except instead of reading into the memory you write from memory into a file.
For example,
Quiz yourself
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