📄 get_next_line

get_next_line reads and returns one line at a time from a file descriptor, implemented from scratch as part of the 42 School curriculum. It handles dynamic line lengths using a buffer of configurable size and static variables to maintain state between calls.

• Language: C
• Norm-compliant (42 coding style rules)
• Uses read(), malloc(), and free() only
• Supports -D BUFFER_SIZE=n compile-time option

• Efficient file I/O using read() with fixed-size buffer
• Use of static variables for maintaining the leftover buffer
• Handling of newlines and end-of-file conditions
• Robust error detection and memory management
• Correct behavior with both files and standard input

Implements char *get_next_line(int fd); that:

• Returns the next line read from fd, including the newline character if present
• Returns NULL at end-of-file or on error
• Works correctly in loops reading multiple lines
• Reads up to BUFFER_SIZE bytes per read() call
• Avoids undefined behavior with binary files or modified inputs

Clone and compile:

git clone https://github.com/IzaroArbaiza/get_next_line.git
cd get_next_line && make

Add the next lines to your code

#include "get_next_line.h"

int fd = open("file.txt", O_RDONLY);
char *line;
while ((line = get_next_line(fd))) {
    printf("%s", line);
    free(line);
}
close(fd);

Compile with:

gcc your_file.c get_next_line.c get_next_line_utils.c -D BUFFER_SIZE=42 -I. && ./a.out