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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.

1. Read Text File In C# Wpf
2. Read Text File In C# Code Project
3. How To Read Text File In C#
4. Read Text File In C# Using Streamreader
5. Read Data From A Text File Using C++ - Tutorialspoint
6. Read Text File In C# Line By Line

How do I read read specific lines of text within a file by search? For example, in the text below, I want to be able to search for the id number of 5 and print all the lines below it until the. Reading a file line by line is a trivial problem in many programming languages, but not in C. The standard way of reading a line of text in C is to use the fgets function, which is fine if you know in advance how long a line of text could be. You can find all the code examples and the input file at the GitHub repo for this article. How to connect a text file to c sharp; read text from rtf file C#; how to read a text file in c; how to write in a text file c#; how to read each letter from a text file in c#; how to read each letter form a text file in c#; read file c sharp; how to open a text file in c#; read a file as string c#; file reading in c#; can i read t from a code. C programming code to open a file and print its contents on screen. Read file C program output: Download Read file program. There are blank lines present at the end of the file. In our program, we have opened only one file. You can open multiple files in a single program, in different modes as required. See full list on programiz.com.

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

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.

Read Text File In C# Wpf

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.

Read Text File In C# Code Project

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,
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How To Read Text File In C#

More on working with files in C
C++ file IO

File I/O in C is very similar to Matlab. There are two main differences. One, we have to type the FILE variable. Two, we read one value (or a single line of values) at a time, whereas by default in Matlab, you may read many values at once.

Read Text File In C# Using Streamreader

The basic steps for using a File in C are always the same:

1. Create a variable of type 'FILE*'.

2. Open the file using the 'fopen' function and assign the 'file' to the variable.

3. Check to make sure the file was successfully opened by checking to see if the variable NULL. If it does, an error has occured.

4. Use the fprintf or fscanf functions to write/read from the file. Usually these function calls are placed in a loop. In the case of reading data, usually, the data is read in and placed in an array, but sometimes we process the data 'on the fly' (i.e., we do not store the data, we process it and create a result directly before reading any more data.

Example Code

Here are examples of the basic syntax for opening a file and writing to or reading from it:

Here is a comparison between reading from a file in Matlab and in C:

Matlab

FGETS function: Read One Line at a Time

Read Data From A Text File Using C++ - Tutorialspoint

To read one line from a file (or the keyboard) at a time, use the fgets function.

fgets places the 'n' (newline) at the end of the line. Thus if we type in 'hello', what really goes into the variable line is [ 'h', 'e', 'l', 'l', 'o', 'n', '0' ]

Read Text File In C# Line By Line

fgets returns the keyword null on error. Thus we often use: