overwrite

问题 How can I create a function to delete certain part of a file? For example, the file is: -. Chair: A23 Number: 123 Name: Joshua -. Chair: B12 Number: 512 Name: Marcus -. Chair: C2 Number: 1 Name: Drake If the input is B12 Then the file shall become -. Chair: A23 Number: 123 Name: Joshua -. Chair: C2 Number: 1 Name: Drake I need this function for my program to work, but I have no idea how can I do that. 回答1: Open a new file in the same directory as the original file. Write to that file what you

问题 I have a program that add persons to an arraylist. What I'm trying to do is add these persons to a text file as well but the program overwrites the first line so the persons get erased. How do I tell the compiler to write at the next free line? import java.io.*; import java.util.*; import javax.swing.JTextArea; public class Logic { File file; FileWriter fw; FileReader fr; BufferedWriter bw; ArrayList<Person> person; public Logic() { try { file = new File("register.txt"); if (!file.exists()) {

问题 I have a program that add persons to an arraylist. What I'm trying to do is add these persons to a text file as well but the program overwrites the first line so the persons get erased. How do I tell the compiler to write at the next free line? import java.io.*; import java.util.*; import javax.swing.JTextArea; public class Logic { File file; FileWriter fw; FileReader fr; BufferedWriter bw; ArrayList<Person> person; public Logic() { try { file = new File("register.txt"); if (!file.exists()) {

问题 using C# VS 2010, windows forms. My goal is to open and close the file only once and "overwrite" it multiple times. I never want to append. The reason for opening and closing the file once is I want the write operation to be fastest. I am passing append = false in streamwriter constructor but it still appends and not overwrite. private void testSpeed() { StreamWriter sw1 = new StreamWriter(@"d:\logfolder\overwrite.txt", false); sw1.AutoFlush = true; for (int i = 0; i < 5000; i++) { sw1.Write

问题 How to join and overwrite data appears to be a common request, but I have yet to find an elegant solution that applies to an entire dataset. (Note: to simplify the data, I will use only 1s and NAs for values and a small subset of columns, but in reality I have hundreds of columns with different values). I have one data table (d1) that has NA values in certain columns and rows. library(data.table) d1 = fread( "r id v1 v2 v3 1 A 1 1 1 2 B 1 1 1 3 C 1 NA NA 4 D 1 1 NA 5 E 1 NA 1")[, r := NULL]

问题 I have 3 tables: dentists, groups, and groupdentlink. Many dentists link to many groups through the groupdentlink table. So I'm trying to make a query where it will insert rows into groupdentlink (linking all dentists in the state with all the groups in the state) but only if those rows don't already exist. In a nutshell I want to add new rows without overwriting existing ones or duplicating them. So the intent of the query is something like: INSERT INTO groupdentlink (f_dent_id, f_group_id,

问题 The following code allows me to create a directory if it does not already exist. dir = 'path_to_my_folder' if not os.path.exists(dir): os.makedirs(dir) The folder will be used by a program to write text files into that folder. But I want to start with a brand new, empty folder next time my program opens up. Is there a way to overwrite the folder (and create a new one, with the same name) if it already exists? 回答1: import os import shutil dir = 'path_to_my_folder' if os.path.exists(dir):

问题 I almost finish a messy code to apply several statistical methods/test to 11 data frames from different watersheds with physico-chemical parameters as variables. I reach the goal, but I need to do this functional. So to start i made a function to compute correlation, and save the results as .txt tables and .pdf images. It works great when run the function to one dataframe at the time (for that you should import each dataframe separately using read.table , which is not written in the code

问题 I have two Maven modules, A and B . A is a dependency of B . Both modules have a resource file named default.properties located in src/main/resources . I need to keep the filenames the same and the location of the file the same in both projects because both A and B are using code which expects the file to be named and located where it is. When building B , A 's default properties is in the final jar . I wish to have B 's properties when I build B . How can I do this? 回答1: Ok, Maven Resources

问题 Say, the code class Derived: public Base {....} Base* b_ptr = new( malloc(sizeof(Derived)) ) Base(1); b_ptr->f(2); Derived* d_ptr = new(b_ptr) Derived(3); b_ptr->g(4); d_ptr->f(5); seems to be reasonable and LSP is satisfied. I suspect that this code is standard-allowed when Base and Derived are POD, and disallowed otherwise (because vtbl ptr is overwritten). The first part of my question is: please point out precise precondition of such an overwrite. There may exist other standard-allowed