How to change a specific number in a specific line in a text file?

Hi,

I have a txt file and I need to change a specific number in a specific phrase. I want to change the number after the phrase:

UINL_Fuel_C1_Inlet1 56

The number after it as of now is 56 and I want to change it to one of my new values called new_velocity that is calculated in my code. I tried using regexprep but it is not working.

Thanks

[Madhu Govindarajan]

Can you share what you tried? Because if I do something like this for a variable called Random it works fine and I am able to save this back into my text file.

>> Random = regexprep(Random,'UINL_Fuel_C1_Inlet1 56','UINL_Fuel_C1_Inlet1 57')

Answer 1

[Walter Roberson]

filecontent = fileread('YourFileNameHere.txt');
newcontent = regexprep(filecontent,'UINL_Fuel_C1_Inlet1 56', sprintf('UINL_Fuel_C1_Inlet1 %g', new_velocity));
fid = fopen('DifferentFileNameHere.txt', 'w');
fwrite(fid, newcontent);
fclose(fid);

[Paige Nardozzo]

Thank you.

[Guillaume]

Note that with arbitrary strings to be replaced it would be much safer to use strrep rather than regexprep, since any character in ([{.+*^$?\| has special meaning for regular expressions.