How can I read a given number of rows from the end of the file using feeds in C ++?

For my implementation of tail shell command in Linux, I need to read certain amount of lines/bytes from the end of the file using stream input/output. Does anyone have suggestions how to do that? I suspect I need to open a file and pass some parameter to the ifstream constructor, but I don't know what exactly. Googling didn't find anything.

Since tail needs to work with pipes, that you can't rewind, you'll have to keep a rotating buffer of the last n lines you've read which you will dump on EOF.

In Laravel, how do you remove a fixed number of rows from the table using the query builder?

I am trying to delete any five rows from my users table. I used following code for that. DB::table('users')->take(5)->delete(); But it deletes all rows in that table. How will I overcome this problem?You said you want to delete 5 rows randomly, in t

How can I select a specific number of rows from a matrix in MATLAB

Suppose, I have a matrix loaded in MATLAB which has 1822 rows and 3 columns. I want to select 1/10 th of the total rows from that matrix. I tried the following, >> train(size(train,1)/10,:) error: subscript indices must be either positive integers l

How do I read an unknown number of bytes from the com port, using boost?

I'm trying to write and read data from com port. I' using write(*ioboard.port, buffer(cpayload, cpayload.size())); for writing and i have some troubles with receiving answer. I tried different variants int m = read(*ioboard.port, buffer(answer, 1));

How do I remove a variable number of rows from the top and bottom of multiple HTML documents?

I have a large number of html documents that need a variable number of lines removed from the top and bottom. The part I want always starts with <div class="someclass"> and the bottom section always starts with <div class="bottomou

How can I get only special strings (by condition) from the file?

I have a huge text file with strings of a special format. How can i quickly create another file with only strings corresponding to my condition? for example, file contents: [2/Nov/2015][rule="myRule"]"GET http://uselesssotialnetwork.com/pic

Python - Prints a random number of rows from the file

If file.txt contains: appple cheese cake tree pie Using this: nameFile = ("/path/to/file.txt") nameLines = open(nameFile).read().splitlines() randomName = random.choice(nameLines) This will only print 1 line from file.txt How would I print 1-2 l

How can I set a maximum number of rows in the MySQL table?

I need to set a maximum limit of rows in my MySQL table. Documentation tell us that one can use following SQL code to create table: CREATE TABLE `table_with_limit` `id` int(11) DEFAULT NULL ) ENGINE=InnoDB MAX_ROWS=100000 But MAX_ROWS property is not

Obtain a specific number of rows from the database using Row_Number; Inconsistent results

Here is my SQL query select * from TABLE T where ROWNUM<=100 If i execute this and then re-execute this, i dont get the same result. Why? Also, on a sybase system if i execute set rowcount 100 select * from TABLE even on re-execution i get the same r

How to get the last duplicate row from the file using Perl

I'd like to get the last entry of a duplicate line from a file. The basis for duplicate checking would be the first element from a csv. The duplicates may or may not be adjacent. Input file: 971~11 972~12 973~11 974~11 972~11 Expected output: 971~11

How can I set a minimum number of rows to display in a UITableView without changing the data source?

How can I set a minimum number of rows to display in a UITableView without changing the data source ? In other words I would prefer to not add empty objects to the data array, to display the empty rows.Maintain two arrays and check like this - (NSInt

The fastest way to read a large number of int from the binary file

I use Java 1.5 on an embedded Linux device and want to read a binary file with 2MB of int values. (now 4bytes Big Endian, but I can decide, the format) Using DataInputStream via BufferedInputStream using dis.readInt()), these 500 000 calls needs 17s

How can I get rid of sticky boot screens from the iPad?

Initially I developed my app as Universal. Then I designed splash screens separately for iPad. Recently I decided to deploy my app in iPhone device mode only. My app has no fancy graphics and it just looks well and works perfect on iPad either in 1x

Get the number of rows from the MSSQL database with Powershell

I'm trying to get the number of rows from a Microsoft SQL database table in Powershell as an integer and am stuck peeling the figure out of the object Powershell is returning. I have; $SQLServer = "MSSQL01" $SQLDBName = "TheTable" $Sql

Write / read from the file using pointers, C

I've written a program to mess around with writing pointers into files(fwrite) and reading into pointers from files(fread). However the program doesn't seem to write a single thing into the file, nor does it seem to read anything from the file; it ju

Related Articles