Introduction
The fgets() function is a powerful tool for reading line-by-line from a file in C programming. It is a standard library function that reads a line from the specified stream and stores it into the string pointed to by the user. This function is useful for reading large files, as it allows the user to read one line at a time, instead of reading the entire file into memory. In this article, we will discuss how fgets reads line after line from a file.
Solution
fgets reads line after line from a file by using a loop. The loop reads each line of the file until it reaches the end of the file. The loop reads each line of the file into a buffer, and then processes the line. The loop continues until the end of the file is reached.
EDIT: added extra explanation as @KlasLindbäck pointed out that my answer wasn’t entirely correct
The File is a struct that contains a field “fd” which is an integer that identifies the OS file descriptor of this file, this file descriptor can be used to retrieve the current location in the file you’re reading. If you want more information about the File struct here and file descriptor here
TL;DR: The FILE struct somehow stores where it’s reading.
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solved How fgets reads line after line from a file?
When reading a file line by line, the fgets() function is often used. This function reads a line from a file and stores it in a string. The string is then used to process the line. The fgets() function takes three parameters: the file pointer, the string to store the line, and the maximum length of the line.
The file pointer is used to identify the file that is being read. This is usually done by using the fopen() function. The string is used to store the line that is read from the file. The maximum length of the line is used to limit the amount of data that is read from the file. This is important to prevent the program from reading too much data from the file.
The fgets() function reads the line from the file one character at a time. It stops reading when it reaches the end of the line or the maximum length of the line. After the line is read, the fgets() function returns the string that contains the line. The string can then be used to process the line.
The fgets() function can be used to read line after line from a file. This is done by looping through the file and calling the fgets() function each time. The loop will continue until the end of the file is reached. This allows the program to process each line of the file one at a time.