Write Data to Text Files in MATLAB (original) (raw)

Last Updated : 23 Jul, 2025

Writing data to a text file means creating a file with data that will be saved on a computer's secondary memory such as a hard disk, CD-ROM, network drive, etc. fprintf() function is used to write data to a text file in MATLAB. It writes formatted text to a file exactly as specified. The different escape sequences used with fprintf() function are:

\n : create a new line \t : horizontal tab space \v : Vertical tab space \r : carriage return \ : single backslash \b : backspace %% : percent character

The format of the output is specified by formatting operators. The formatSpec is used to format ordinary text and special characters. A formatting operator starts with a percent sign% and ends with a conversion sign. The different format specifiers used with fprintf() function are:

%d or %i: Display the value as an integer %e : Display the value in exponential format %f : Display floating point number %g : Display the value with no trailing zeros %s : Display string array (Unicode characters) %c : Display single character(Unicode character)

Now let's start writing data to a text file. Before writing to a file, we need to open the text file using fopen() function. To open a file, the syntax is:

f=fopen(File_name, Access_mode)

Here,

fopen() function accepts two arguments:

• name of the file or File_identifier.
• type of access mode in which the file is to be open. We need to write data, so the access mode can be 'w', 'w+', 'a', 'a+'.

Let's see different ways to write data to text files are:

Example 1:

Matlab `

% Writing array of integers

a= [1,2,3,4; 5,6,7,8; 9,10,11,12;13,14,15,16]; file=fopen('GfG.txt','w'); fprintf(file, '%3d %3d %3d %3d \n',a);

`

Output:

Note: If the file name is not specified then the result will be displayed on the screen.

Example 2:

Matlab `

% Writing floating point values and % string literals to a text file a = [1.500,2.500, 3.500,4.500];

% 4.2 means floating number with 4 digits % including 2 digits after the decimal point formatSpec = 'a is %4.2f \n';
file=fopen('Gfg.txt','w'); fprintf(file,formatSpec,a); fclose(file);

`

Output:

Example 3:

Matlab `

% MATLAB code for Writing data to % text file using mathematical function x = 1:10; A = x.^2;

fileID = fopen('power.txt','w'); fprintf(fileID,'%4s %4s\n','x','power^2'); fprintf(fileID,'%4.2f %5.2f\n',A); fclose(fileID);

`

Output:

Example 4:

Matlab `

% MATLAB code for writing % hyperlink to a text file url = 'https://www.geeksforgeeks.com/'; sitename = 'Web Site for geeks'; f=fopen('gfg.txt','w'); fprintf(f,'%s\n',url,sitename); fclose(f);

`

Output: