fgetl

Read line from file, removing newline characters

Syntax

tline = fgetl(fileID)

Description

tline = fgetl(fileID) returns the next line of the specified file, removing the newline characters.

• If the file is nonempty, then fgetl returns tline as a character vector.

• If the file is empty and contains only the end-of-file marker, then fgetl returns tline as a numeric value -1.

Examples

Read File One Line at a Time

Read a single line from a file, first excluding newline characters, and then including them. Use the following file.

To read the first line from the file badpoem.txt, use fopen to open the file. Then read the first line using fgetl, which excludes the newline character.

fid = fopen('badpoem.txt');
line_ex = fgetl(fid)  % read line excluding newline character

line_ex = 
'Oranges and lemons,'

To reread the same line from the file, first reset the read position indicator back to the beginning of the file.

frewind(fid);

Use the fgets function to read the first line from the file badpoem.txt, which reads the line including the newline character.

line_in = fgets(fid) % read line including newline character

line_in = 
    'Oranges and lemons,
     '

Compare the output by examining the lengths of the lines returned by the fgetl and fgets functions.

length(line_ex)

ans = 
19

length(line_in)

ans = 
20

fgetl returns an output that displays in one line, while fgets returns an output that includes the newline character and, therefore, displays it in two lines.

line_ex

line_ex = 
'Oranges and lemons,'

line_in 

line_in = 
    'Oranges and lemons,
     '

Close the file.

fclose(fid);

Input Arguments

fileID — File identifier

integer

File identifier of an open file, specified as an integer. Before using fgetl to read a line from the file, you must use fopen to open the file and obtain its identifier fileID.

Data Types: double

Tips

• fgetl reads characters using the encoding scheme associated with the file. To specify the encoding scheme, use fopen.

• When fgetl encounters the ASCII characters in the order 0A 0D, which are a line feed followed by a carriage return, it will read them as a single ASCII newline character.

• To read lines from a file while keeping newline characters, use fgets.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• If the function fgetl does not read content from the file, then the generated code reports either an error or returns an empty value instead of returning -1.

• If the function fgetl reads a null byte, the returned values might be truncated.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced before R2006a

R2024b: Read data over HTTP and HTTPS using low-level file functions

You can read data from primary online sources by performing low-level file read operations over an internet URL.

R2022b: Use function in thread-based environments

This function supports thread-based environments.