fwrite

问题 I am currently trying to use UDP to send constant values from MATLAB to Simulink and then use Simulink to graph these values. Here is an image of the MATLAB code, Simulink block diagram and the graph that I am working with (note that the graph starts at a constant value of 0): http://i.imgur.com/krkulyQ.png In the MATLAB code I am using the fwrite function to send data to the Packet Input block which then outputs to the Scope block to graph the data. Specifically I would like to graph

问题 Let's consider the datatable : > dt=data.table(v1=1:10, v2=c(rep("a",5),rep("b",5))) v1 v2 1: 1 a 2: 2 a 3: 3 a 4: 4 a 5: 5 a 6: 6 b 7: 7 b 8: 8 b 9: 9 b 10: 10 b How would I do to export dt into as many files as there are v2 naming the files after them ? Meaning one file named a containing 1 2 3 4 5 and one file named b containing 6 7 8 9 10 . I tried : dt[, fwrite(.(v1), v2), by=v2] but to no avail. Alternatively how would I export the dt into one single file formated as following : 1 2 3 4

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 I'm somewhat of a newbie to C++ (moving from C#) so I'm not exactly sure what's going on here. What I'm trying to do is read an image out of a file and write it to an output file, but whenever I do parts of the file appear to be corrupt. I've checked the data in memory and it actually matches, so I believe the culprit has to be something going on with fwrite(), although it could always just be something I'm doing wrong. Here's some sample data: http://pastebin.com/x0eZin6K And my code: //

问题 I have an array whose structure is like $data = array{0=>'abc',1=>xyz,2=>tqs} Now I need to write these values into a csv file. I need to display every value in 1st column and with everytime new row on new insert along with previous value already available. Below is the code I am using but everytime I execute it I get the last value in the file: for ($c=0; $c < $num; $c++) { echo $data[$c]; echo $query = "select prod_sku,prod_name from tbl_product where prod_sku = '".$data[$c]."'"; $result =

问题 I have a simple PHP script that writes a file into directory where located, but need to have it written into a directory called "temp". There are many answers here on the subject, but can't seem to find what I need. Have reviewedhttp://us2.php.net/manual/en/function.fwrite.php with no luck. Here is the basic PHP without the form part: <?php function saveFile($filename,$filecontent){ if (strlen($filename)>0){ $file = @fopen($filename,"w"); if ($file != false){ fwrite($file,$filecontent);

问题 Profiling my program and the function print is taking a lot of time to perform. How can I send "raw" byte output directly to stdout instead of using fwrite, and making it faster (need to send all 9bytes in the print() at the same time to the stdout) ? void print(){ unsigned char temp[9]; temp[0] = matrix[0][0]; temp[1] = matrix[0][1]; temp[2] = matrix[0][2]; temp[3] = matrix[1][0]; temp[4] = matrix[1][1]; temp[5] = matrix[1][2]; temp[6] = matrix[2][0]; temp[7] = matrix[2][1]; temp[8] = matrix

问题 If you are writing to a file with python, is there any way to make certain parts of the text bold, italic, or underlined ? i tried: test = '/location/tester.rtf' out_file = open(test,'w') out_file.write('is this {\bold}?') out_file.close() #thanks to the comment below is it possible to write FORMATTED TEXT like bold, italic, or underlined text via python ? i feel like .rtf is the most basic formatted text but correct me if i'm wrong 回答1: Just been playing around with this assuming MS word, I

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-