How to find the positions of a string which occurs multiple times

I have a file which contains many scans,and for each scan there is the following line "par 1 f1:'Amplitude ' 1.270660e-001 3.178370e-003 0" I wish to find and extract the data contained in this line everytime it appears.

[Jan]

Why? If it is exactly this line, you can parse it once manually. Or is there any additional information?

Please explain the file format more explicitely: Is it a text file? ASCII or Unicode? Are the lines separated?

[David]

The file format is an ASCII,it contains 20 scans. so the first 20 lines are text lines from the first scan which include the amplitude data which i need, there is then 20 lines of numerical data and then the 20 lines of text from scan 2 and so on, there is no scan identifier though so i need to find every occurence of Amplitude and extratct this string. The lines are not seperated.

[Jan]

Fine. Can you post what you have done so far and explain, where the problems occurred?

[David]

I can find the string the first time it occurs in the file and extract the text required, however i am unable to get this process to go through the entire file and return every instance of 'Amplitude'. I have imported the data so i have one object which contains the numerical data and one object which contains the text, i can find the indexes of where ampliyude occurs by using the strcmpi, which returns a logic array with a 1 where the phrase occurs and a zero otherwise. I then find the indecies of these 1's by using find(X) which tells me which cells in the array contain 1's. so i have the indecies of the text data which i want to extract but i dont know how to then create an array where it picks out these indicies from the original text data

Answer 1

[Grzegorz Knor]

doc fopen
doc fgetl
doc strfind
doc strcmpi

Answer 2

[Fangjun Jiang]

use textscan(), you may also need to use fopen(), fclose().