fread

问题 This question already has answers here : Reading very large files in PHP (8 answers) Closed 5 years ago . I have few text files with size more than 30MB . How can i read such giant text files from PHP? 回答1: Unless you need to work with all the data at the same moment, you can read them in pieces. Example for binary files: <?php $handle = fopen("/foo/bar/somefile", "rb"); $contents = ''; while (!feof($handle)) { $block = fread($handle, 8192); do_something_with_block($block); } fclose($handle);

问题 I am reading a 1 GB file using fread in C. I am reading the file in 1MB chunks, using the following loop: FILE *fp; fp = fopen(filename, "rb"); unsigned char* buf; buf = malloc(CHUNK_SIZE); for(i = 0; i < NUMBER_OF_CHUNKS; ++i) { fread(buf, CHUNK_SIZE, 1, fp); //Do something with contents of buffer } fclose(fp); Reading the file this way takes ~2 seconds. However, I decided that I wanted to allocate one big buffer for the contents of the whole file instead and "move the buffer pointer" inside

问题 I have an application that is recording live , the capture file keep growing in size using fread() and feof() , but feof() is breaking the loop early , so what's the best technique to keep reading from the stream should I wait and then I can advance the file stream ? should I open the file again and advance to position by calculating the total of read bytes? maybe something else ? the code will have to read the file , build a packet and send it packaging and sending is going well with fixed

问题 update (June 2016) col.names was added on data.table 1.9.6 so issue is over and everyone super happy :) I think I can now convert all my read.csv calls to fread calls without worries of destruction original question using data.table 1.9.4 I'm importing read.csv calls to fread due to HUGE performance improvements we've noticed. Most issues I can handle but I've reached a point where I'm clueless and wonder if anyone has an elegent solution. My problem is that I have named colClasses but the

问题 Lets say I have a modestly sized text file (~850kb, 10,000+ lines) And I want to replace a particular line (or several) spread out amongst the file. Current methods for doing this include re-writing the whole file. The current method I use is read through the entire file line by line, writing to a .tmp file, and once I am done, I rename() the tmp file to the original source file. It works, but it is slow. And of course, as the file grows, so will execution times. Is there another way (using

问题 What's the cleanest way in php to open a file, read the contents, and subsequently overwrite the file's contents with some output based on the original contents? Specifically, I'm trying to open a file populated with a list of items (separated by newlines), process/add items to the list, remove the oldest N entries from the list, and finally write the list back into the file. fopen(<path>, 'a+') flock(<handle>, LOCK_EX) fread(<handle>, filesize(<path>)) // process contents and remove old

问题 In R Documentation for fread() it's said that "input" argument may be a URL starting http:// or file://. However in this "Introduction to data.table" vignette fread() is used with https: flights <- fread("https://raw.githubusercontent.com/wiki/arunsrinivasan/flights/NYCflights14/flights14.csv") That results in "Error in download.file(input, tt, mode = "wb") : unsupported URL scheme" console message. I can't figure out how to make it work. I've tried settings options(download.file.method =

问题 I am fairly new to R , and have been using data.table a lot recently for a project involving manipulation of large data sets, specifically genome data. One of the columns is the chromosome number/name, which is formatted as "chr_", where the _ is 1-22, X, or Y. As the data is sorted by chromosomal position, this is a natural primary key for my data. However, setting this as the key produces unwanted results, namely sorting by lexicographic order rather than general numeric order (i.e. the

问题 <?php $file_name = $_FILES['files']['name']; $tmp_name = $_FILES['files']['tmp_name']; $file_size = $_FILES['files']['size']; $file_type = $_FILES['files']['type']; // The codes written above work fine and have proper information. $fp = fopen($tmp_name, 'r'); // This one crashes. $file_content = fread($fp, $file_size) or die("Error: cannot read file"); $file_content = mysql_real_escape_string($file_content) or die("Error: cannot read file"); fclose($fp); .... I'm a newbie to PHP stuff. I'm

问题 This is a test program that I have written for a larger project that I am working on. It has to do with writing struct data to disk with fwrite() and then reading that data back with fread(). One member of the struct is dynamically allocated. First, here is my code #include <stdio.h> #include <stdlib.h> #include <string.h> #define STRING_LEN 128 struct Person { int age; char *name; }; int main(int argc, const char *argv[]) { struct Person *person = calloc(1, sizeof(struct Person)); person-