C++ :: Avoiding Reallocation Costs When Inputs Are Unbounded
Jul 9, 2013
how to handle reallocation costs when input data is unbounded.
For instance, in a low-latency environment such as a trading platform or real-time data collection system or MMORPG where you can receive a large amount of input, you can not afford a stall while the data structure is rebuilt with a larger buffer. You can use historical data to "guess" an appropriate size but this is far from fool-proof. You can also create a sentinel thread that monitors the load factor of your data structure but that brings its own problems (e.g. another thread that needs execution time and to lock the data).
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Jun 17, 2013
Here is the code,
Code:
vector<int> v;
for(int i = 0;i<1000;++i)
v.push_back(i);
Is it possible to know how many reallocations happen during the loop?
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Feb 14, 2015
I have a data grid view
ProductID|Name|Category|Description|quantity
1|Coat|men|black coat|5
2|Jacket|men|green jaacket|2
3|Pillow|Home|white|10
a user can edit quantity ie productID 1 has quantity 10, and ProductID 2 has quantity 3, it should update once clicked update button. however i must highlight both rows to do it so if i leave the selected cell on product id 3 it will upate only that row. is there a way to update the rows that have been changed when not highlighted.
for (int i = 0; i < dataGridView1.SelectedCells.Count; i++) {
int selectedrowindex = dataGridView1.SelectedCells[i].RowIndex;
DataGridViewRow selectedRow = dataGridView1.Rows[selectedrowindex];
string a = Convert.ToString(selectedRow.Cells["Quantity"].Value);
string b = Convert.ToString(selectedRow.Cells["ProductID"].Value);
//update to database.....
}
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Oct 5, 2012
The point of this is to calculate the total of the monthly costs of these 6 expenses and then to show the annual cost. However, there's just a couple of things that's giving me problems and it's the calcMonCost in my code. The error says that it is more than one instance of overload function and also that an unresolved external symbol. Everything else is fine. What does this mean?
Code:
#include <iostream>
#include <iomanip>
using namespace std;
void calcMonCost (double, double, double, double, double, double &);
void calcAnnCost (double, double, double, double, double, double &);
void getData(double &lnPymnt, double &insure, double &gas, double &oil, double &tires, double &maint);
[Code] .....
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Mar 25, 2014
I tryed to create program I wich u can guess number, I made some if to prevent inputting 2 times the same number It works. I tryed to apply the same process for generating
#include <cstdlib>
#include <iostream>
#include <stdlib.h>
[Code]....
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Sep 26, 2014
I have made the following code to illustrate my problem:
#pragma once
#include <bitset>
#include <iostream>
[Code].....
Now I want to avoid my bitset field being constructed before the ConstructTest constructor is called. So at first I tried wrapping it in a unique_ptr but found out that this would give me some potential problems with const functions.
And then I realized I could just set it to NULL, as I have in the above code. I tried that, got unexpected print outs, until I found out that NULL is just equal to 0 in C++ and that the bitset has a = operator that takes a number, int, long or maybe something else. Either way, this effectively constructs the bitset and sets it to the number 0.
So my efforts so far have been shut down. But then how can I avoid the bitset being constructed in advance, if at all possible?
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Jan 6, 2015
I've just started working on a Database application and maintaining a previous developer's code, one thing I see is that column and table names are hardcoded throughout the code which is something I'd like to avoid. To me it seems like a practice that is prone to spelling mistakes reaping havoc across the application.
Some I've looked at include:
Constant strings
const string TableName_ColumnName = "TestName";
Dictionary and Enum:
public static string GetColumnName(ColumnId inColId)
{
[Code]....
I think I prefer the second option but it means that retrieving the column names means quite a long winded function call.
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Nov 29, 2013
Code:
#include <stdio.h>
int main(){
int A, B;
char decision;
printf("Do you have an integer to input? [Y/N]: ");
scanf("%c",&decision);
if(decision=='Y' || decision=='y'){
[Code]....
After entering a single integer, it doesn't scan again for another integer. What's wrong?
I'm using a mac btw, if that makes a difference with Ubuntu/Linux.
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Dec 7, 2014
I have learnt recently how to use fgetc, fputc, fputs, fgets but still I am not able to figure out how to read values from a file like for example:
12 14 1928 32993932
17 98
166 109 201
These are separate integers & i want to read them and then manipulate these individual integers like going for 2*I1, 4*I2 and so on where I1 and I2 are 12 & 14.
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Apr 9, 2014
I want to have calculations take place inside a switch statement that calls the appropriate function. The menu portion of the program works well, but I can't figure out how to let the user actually input 2 different numbers to the functions. My questions are:
1. If I use scanf to assign values to the variables, what determines end of input to each variable? (ie.. scanf("%d%d", &a, &b) what is the end of a, what is the end of b?)
2. Should I assign the variables to user input inside the switch, or try to do it in the functions below?
3. Is there something I haven't thought to ask that will screw me over? I'm really new to this.
Code:
#include<stdio.h>
int add(int b, int a);
int mult(int b, int a);
main() {
[Code] ....
This really was a test of multilayer menu, but I want to add functionality if I can.
Changed a variable before posting and didn't change all the conditions testing it.
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Sep 27, 2013
On my program I use a counter to count to 10, then i ask for a string, in this case "yes" or "no", during the count, i want to keep the user from putting inputs in, due to the fact that if they put both "yes" and "no" before the program reads the string.
Code:
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <stdbool.h>
#include <time.h>
#include <string.h>
}
[code]....
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Mar 2, 2014
it skips the input phase,, instead of inputting the last name it goes directly to the firstname then middle initail and street name are working fine but it skips the street name then goes to city and so on....
Code:
char l[50], f[50], m;char strtname[50], cty[50], cntry[50];
int strtnum, zp, i;
system("cls");
printf("Enter Last name:");
gets(l);
printf("
Enter First name:");
}
[code]....
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Jul 23, 2014
I have a project that requires I take user input from menu options and put it into an array which I will average out. I can set the menu up I think, but I cannot understand how to put what the user inputs into an array. Granted I just took the lecture on arrays today. Also we can only use functions to do the work.
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Nov 23, 2014
I don't know how many numbers will be the input only that its going to be up to 10000. EOF should be active. I tried it like this:
Code:
int i = 0;
int del[10000]
while (scanf("%d",del[i])!=EOF)
{
i++;
}
But it seems the value of i doesn't increment, could you provide some tips on how to scanf the inputs into an array if I don't know how many numbers will I have?
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Oct 26, 2013
Any chances for a c program to check for browser inputs?
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Feb 14, 2013
For a program I am required to use a cin that accepts 4 variables. The first describes a function such as add(), remove(), print(), or quit(). The problem is that to use add() I need to input all 4 variables but for remove(), only 2 variable input is needed.
I want the input to be "add 9 James Bond"
or be "remove 341"
Here is my current code.
int command(string command, int Id, string first, string last){
while (command != "quit"){
cout << "customers> ";
cin >> command >> Id >> first >> last;
if (command == "add")
[Code] .....
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Feb 10, 2013
I am new to C++ and I want to learn how to set color a particular color for the users input and output. For example, I want to display the users input as green, and their output as red.
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Jul 19, 2013
How to combine the if statements?
cout<<"Enter a sale number"<<endl;
cin>>rec.sale;
if(cin.fail())
{
cout<<"Enter a number"<<endl;
cin>>rec.sale;
}
[Code]...
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Feb 1, 2013
How to use library management inputs
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Feb 23, 2013
Make a C++ Program that will use nested if else and any looping statement to display the following a certain number of times depending on how many times the user wants it to do so.
Input Values:
1. Name of employee
2. Position in the company
3. No. of hours worked
4. Rate per hour
5. Overtime hours
Required Output:
No. Name Position Rate per No. of hours Basic No. of overtime Overtime
hour worked Pay hours Pay
1. Juan Manager 160 140 22400 10 2100
Computations:
basic pay = no. hours worked x rate per hour
overtime = overtime hours x 150% of rate per hour
Just asking how can I input the name, position, rate per hour, overtime hours and hours worked in a horizontal manner?
Because I need to achieve the required output.
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May 26, 2014
How to make an input with a string thats part of an if statement. How I think it should be done :
#include <iostream>
#include <string>
using namespace std;
int main() {
string choose;
[Code] .....
But I get a strange warning (not an error, but something that is like "just letting you know" i suppose) and when i enter in ss or SS or aa or AA, it breaks my app.
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Mar 16, 2014
How to get user inputs into an array. I have to get 10 user inputs into the array and I'm trying to use a loop but once I run it it crashes whenever you input the first value. This is my absolute first time working with arrays and I've been trying to do research
#include <stdio.h>
#define SIZE 10
void Input(const int array1[]);
void Calculations(int array1[], int average);
void Output(int array1[], int average);
[Code]....
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Oct 6, 2014
my lecture notes had this chunk of code on it. Which was the way to let a user enter not more than 40 different numbers , and save it into an array. The code is as follows :
#include <stdio.h>
#define MAX 41
void readData(int num[] , int * count);
[Code]...
In the function readData , why is n being scanned before and during the while loop?
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Nov 26, 2013
It's not something trivial but I would like to know the best way to process multiple outputs, for example:
Input
First line of input will contain a number T = number of test cases. Following lines will contain a string each.
Output
For each string, print on a single line, "UNIQUE" - if the characters are all unique, else print "NOT UNIQUE"
Sample Input
3
DELHI
london
#include<iostream>
Sample Output
UNIQUE
NOT UNIQUE
NOT UNIQUE
So how can I accomplish outputs like that? My code so far is:
Code:
int main(int argc, char *argv[]) {
int inputs, count=0;
char str[100];
char *ptr;
scanf("%d",&inputs);
[Code] ....
But the above will obviously print the output after each input, so I want to know how can I achieve the result given in the problem. Also another thing I want to know is, I am using an array of 100 char, which it can hold a string up to 100 characters, but what do I have to do if I want to handle string with no limit? Just declaring char *str is no good, so what to do?
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Jul 31, 2013
I have recently looked into a self created project where I wanted to compare user input against a list of strings in an external file. That has since been completed to my great satisfaction, however it did throw up some interesting issues in my knowledge and understanding of user input..What is the best way to pick up user input i.e scanf,stdin etc. and when should either be used and can a mixture of types be used, and if so, when and why.
A quick program to take different input methods and display differnt output method (obviously corresponding i.e scanf/printf - fgets/fputs)
My first pothole came when I have setup the method for scanf - fine. Then I setup the method for fgets(test,100,stdin) for example and the fgets method no longer picks up stdin from the user..
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Jan 23, 2014
I am beginner at C and I was working on a program where I have to read in a line such as Digit, String, Float. The string can have any amount of spaces between it. and each input is separated by a space character.
The input is of the format:
10000000000 hello my n ame is 30.2
So I used fgets(x,100,stdin) to read the line in.
So I need to read that line into an int, array, and float.. so I was thinking of using this:
sscanf(x, "%d %[^/n] %f", &number, &username, &numberfloat);
Now, obviously I can't use the /n to read in the username with spaces because I need to read the 30.2 into a float variable.
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