C Sharp :: Converting DB Variable To Double In C#
Aug 22, 2012
I'm having some trouble with a variable from a database. That variable in that database is of type double.
To read from the database, I'm using a variable dr of type OleDbDataReader.
So far, I've been using dr["variablename"].ToString() to work with the variables from this database - without the ToString part it wasn't working.
However, with this specific variable (I'll call it "var"), I have to do numerical comparisons of >= and <=, so obviously, just using dr["var"].ToString() doesn't work.
Therefore, I tried creating a variable of type double called varConv and setting it as
varConv = Convert.ToDouble(drPen["var"].ToString()).
That doesn't work, gives me an error message saying "Input string was not in a correct format". If I remove the ToString part, it also doesn't work, with a different error message saying "Object cannot be cast from DBNull to other types".
Trying to do a direct comparison, as in dr["var"] >= x also doesn't work, says "Operator '>=' cannot be applied to operands of type 'object' and 'int' ".
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May 10, 2013
I would like to convert a float or double variable into unsigned char variable and back.
float number_float = 23.453f;
unsigned char* number_char = (unsigned char*)malloc(sizeof(float));
number_char = reinterpret_cast<unsigned char*> (&number_float);
float* number_float_0 = reinterpret_cast<float*>(&number_char);
I am not getting the same value back.. why?
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Dec 7, 2014
I'm trying to find a way to accuratley convert a double in the form of a bank account number stored in a file into a string representing the number returned by a file.
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May 2, 2013
i think i need to convert a double to a string, we are working in visual studio doing a program. when i run the calculator i'm not getting the answer i need instead its giving me 0.0 when it should be reading 0.5, here is the code i'm using
{int width;
int height;
int area;
double gop;
String ^strWidth;
String ^strHeight;
String ^strArea;
String ^strGop;
strWidth=width1->Text;
[Code]....
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Mar 11, 2013
I have a problem with converting a C++ string into a long double. In order to do this, I used the function strtold, but the result I get is only the integral part, that is: if for example the input string is 12.476, I only get 12 as the converted long double value. This happens with atof too.
Here is my code:
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <sstream>
string test = "12.345";
long double test_longd = strtold(test.c_str(),NULL);
[Code] .....
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May 18, 2014
I am having a lot of trouble extracting values from a string into a double array.
I have a string that looks something like this: "asdf 1.320 1 234.43 5.00000 3"
All I want to do is extract the doubles and store them in an array of doubles.
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Jun 15, 2014
So I have problem with my code, I'm trying to convert string to long and then string to double, but I get this when I compile it:
terminating with uncaught exception of type std::invalid_argument: stod: no conversion
I was thinking if there is a way to do this without using (stol) or (stod)
Market::Market(string filename)
{
string line, word, date, stockprice;
long realdate;
[Code].....
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Aug 26, 2014
I am trying to convert multiple lines of strings to double with std::stod .... I used the code found on the website:
#include <iostream>
#include <sstream>
#include <string>
#include <fstream>
int main() {
std::string two_doubles =" 22145.365 -3564789";
std::string::size_type K;
double first = std::stod (two_doubles, &K);
double second = std::stod (two_doubles.substr(K));
}
The string starts with white spaces. I get this error message when compiling:
warning unused variable 'first'
warning unused variable 'second'
How do you convert the two numbers in the string two_doubles to doubles?
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Dec 22, 2014
I have int pointer called p and i want to calculate average.Since average involves using double or float so i am trying to convert this in the function averagetemp. It still gives me an error saying "cannot be converted"...
#include <iostream>
using namespace std;
int* createArray(int n);
int lowesttemp(int *p,int f);
int highesttemp(int *p,int f);
double averagetemp(int *k,double f);
void print(int *p,int lowest_temp,int highesttemp,int average_temp);
[Code] ....
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Jul 28, 2013
I am trying to write a Fraction class and getting the following warning when compiling my code :
Fraction.cpp: In constructor 'Fraction::Fraction(double)':
Fraction.cpp:8: warning :converting to 'int' from 'double'
My Fraction.cpp class looks like :
#include "Fraction.h"
Fraction::Fraction(int n, int d):num(n),den(d) {
cout << This is double param constructor <<endl;
}
Fraction::Fraction(double d):num(d),den(0)
[Code] ....
How can I get rid of the warning ?
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Jun 4, 2013
I am writing a math program, using variables of type double, and had initialized all variables to 0.0.
I now realize that not all results will be valid.
Is there a way to explicitly assign a variable of type double a non-numeric value, for example, "NaN", "Undefined", or "Unassigned" or something like that?
That way, when I read through the printout of results, I will realize the "NaN" results indicate a valid solution was not found. Whereas a 0.0 might not stand out.
I'd hate to have to go back and delete the initialization, and then re-assign 998 values just for the sake of 2 non-solutions.
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Apr 4, 2014
Define a constant PI that has a value of 3.14159
- Create a double variable, Radius with an initial value of 10
- Create two double variables. Circum and Area, without initialization
- Using the following formulas, compute circumference and area of the circle:
circumference = pi * r * 2 (here, r means radius)
area = pi * r * r
- Display the result using three variables (numbers must come from variables)
- Expected output: (Don’t forget to display the period at the end of the first line)
Circle with radius of 10.
Circumference = 62.8318 Area = 314.159
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Apr 11, 2014
I would like to convert a string variable to float.When acquiring data from text file, I use:
while( getline( ifs, temp )) {
numberOfFeatures++;
vecteur.clear();
string::size_type stTemp = temp.find(separateur);
number_descriptorEntries=0;
[code].....
the matrix that I obtain is of type vector<Vec> where Vec is a vector of strings.I want to convert each element of matrixe to a float.
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May 7, 2013
Is there a quick way to determine if a value is in an enum? Consider for example,
public enum GenderEnum
{
Unknown = 0,
[Code].....
I don't want to convert to an array if possible, just check the enum and get a yes/no answer.
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Apr 9, 2013
I want to add ComboBox inside ListView on mouse double click event. On each double click, a new ComboBox should be added on the next row.
I tried it with the code below, but its not working.
private void form_DblClick(object sender, form_DblClickEvent e)
{
ComboBox c;
this.Controls.Add(c = new ComboBox());
c.Items.Add("Input");
c.Items.Add("Delay");
c.Items.Add("Message");
c.Items.Add("comment");
listView1.Controls.Add(c);
}
actually i want to add combobox will all of the above elements in one combobox..when i double click it again..in next line another combobox will be added with all elements...
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Aug 27, 2014
I am trying to query an Informix database using a List<T> collection's elements as variables. I can build the list and connect to the database, but I am unsure how to iterate through the list and query the database for each item in the collection.
My list is of type string, and contains Order Numbers. I want to query item information for each order number in the list.
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Jan 1, 2014
I have an application in C sharp that searches for a record in a sql database using a datetimepicker,the output is displayed in a datagridview.When I execute it I got a blank datagridview with empty columns.I can not view the content and I don't get any error message.
Here is my code:
DataTable dt=new dataTable();
SqlDataAdapter sda=new sqldataadapter("select * from Delivery where convert
(char(20),Delivery_Date,112)='"+ dateTimePicker1.value.Date,con);
//con is sqlconnection
Sda.Fill(dt);
Datagridview1.DataSource=dt;
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Dec 26, 2013
I want to store values permanently in a variable. The same variable should be able to be edited and saved by user, and whatever it is I need the value of the variable from the last time I modified it, like a database. database because i need this to set my connection string of the database.
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May 1, 2013
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
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Mar 2, 2013
This problem is best explained by looking at its output below. I stored 15 different values but when retrieved some are wrong.
#include <iostream>
using namespace std;
class A {
public:
int ** pointer;
[Code] ....
I need to store and retrieve the 15 different values correctly. How to solve this? The main thing is, I need to store the pointer in class A objects.
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Sep 8, 2013
I have to write a loop assigning a variable x to all positions of a string variable and I'm stuck. I don't have extensive experience with arrays and I'm also a bit confused about C-String. The problem is below.
"Given the following declaration and initialization of the string variable, write a loop to assign 'X' to all positions of this string variable, keeping the length the same.
char our_string[15] = "Hi there!";
(Please note this is a 'C-string', not C++ standard string.)"
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Oct 25, 2014
I need to transform a local variable into a global variable so I can use it in one of my functions. I thought about passing the value as a parameter to this function but I can do this since the function is called inside the while loop and this variable counts how many times the while loop does (so the final value is outside the loop). Example to visualize better:
Code:
while(condition) {
function(parameter1, parameter2);
count = count + 1;
}
printf("%d
", count);
So, I need to transform the final value of "count" into a global variable. Can I do this?
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Oct 15, 2013
I want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like
struct item {
int ID;
int special; // for function
};
item Key;
Key.special = UseKey(KEY_KING);
// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this
if(iCurrRoom == ROOM_KING)
Key.special;
else if(iCurrRoom == ROOM_DRAGON)
Fireball.special;
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Feb 3, 2014
I've been experimenting with pointers and am getting the below error.
'error: cannot convert 'int**' to 'int*' in assignment'
I thought it was ok to assign a variable address to another variable. Line 18 is where I get the error.
I am trying to show the progression of memory as I increment it as I have done on line 17 and again, I don't know why I don't see a progression through memory locations when output to the console on line 20.
Here's the code:
#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;
int main() {
int *tt = new int;
int *p = new int;
[Code] .....
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Jun 16, 2013
Any way to create a variable using a variable in the name? So E.g. if you wanted to create an int named nr(x), and x was 1, you would get an int variable named nr1? How would you do this?
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Jul 31, 2013
#include<iostream>
using namespace std;
int main() {
double x,i;
cout<<"Enter the value of the number
[Code] ....
why I am not getting exact square root if I take x as double,but if I am taking it as int I got the correct result.
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