C++ :: Inserting Math Functions From GUI
Feb 8, 2013
I have a problem with entering math functions in my Bisection method algorithm program. I just don't know how can I make the function that I enter in my GUI app to go from the GUI to the loop and find the root.As far as I googled I only find codes that you need to pre-enter a function in the double/float.
For example:I have a function f(x) = x^3 - cos(x) - x - 3; and I want to enter that function trough the GUI i made in c++..So this is the main code.
#include "bisection.h"
#include "ui_bisection.h"
#include <QFile>
#include <QString>
#include <math.h>
#include <algorithm>
bisection::bisection(QWidget *parent) :
[code]....
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May 1, 2013
I'm writing a function that inserts a row into a matrix and deletes the last row.
But I'm having trouble. What do I need to add to this function:
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Jan 30, 2013
I have a program that stores values in a map>. I use the map as a dictionary so that I can look through my map if a perticular string already exists. If a string does exist, I want to put the position that I found it at (relative to my text file) in my vector. How do I do this? So far I've tried this:
void mapInsert(string aWordNoSpaces, int index){
// check if word exists in map already, but first we need an iterator object
map<string,vector<unsigned int>>::iterator it;
it = wordMap.find(aWordNoSpaces);
if(it == wordMap.end()){
wordMap.insert(pair<string,vector<unsigned int>>(aWordNoSpaces,index));
[Code]...
Also, why are the zeros showing up here (i've attached a screenshot and circled them): [URL]...
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Sep 22, 2014
How would one write 3^i without using .math? (i being numbers 0-9)
More specifically, this is what I have:
Code:
#include <stdio.h>
#include <stdlib.h>
int main(void) {
int x, n, answer1, first;
x = 3;
n = 10;
first = 1;
[Code]....
And this is what I want it to produce:
1 0 1.0
3 1 0.333333343
9 2 0.111111112
27 3 0.037037037
81 4 0.012345679
243 5 0.004115226
729 6 0.001371742
2187 7 0.000457247
6561 8 0.000152416
19683 9 0.000050805
I believe I am only having troubles with the first column,
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Aug 11, 2014
I've used qsort to extract the unique student IDs by jumping every four because there's 80 rows of data and twenty students.
I want to make sure it's all working and there's something very strange going on. If you look at my code, when it comes to initialising the structure with the unique student IDs it will happily print them after each one has been initialised inside the for loop (which suggests to me it's obviously done it) but, however, when I want to print them again outside the for loop in another for loop as a "double-check" it goes horribly wrong, presumably they're not in there at all? If you traverse the code to the bottom you'll see my comments.
Now in my for loop, j is going to be incremented 20 times which will correspond to the #define STUDENTS 20. So imagine the array of structure db[j] , the first loop will set i and j both to zero, retrieve the first unique ID and store it in the structure. Then i is incremented by four to acces the next unique ID and then j is incremented by 1 to insert this new ID in the structure.
Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
[Code]....
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Jun 11, 2013
I have a pointer to a C string that contains multiple lines of text. I need to change a few characters in the string (possibly adding 1-2 extra). At the moment my code looks like this (char **objectData is the pointer):
Code:
char temp[350];
char* end = strstr (*objectData, "word_before_data_changes");
strncpy (temp, *objectData, 39); // Copying the first 39 symbols
strncat (temp, "6-11", 4); // inputting some data
strncat (temp, end, 100); // copying the last symbols.
I don't know how many there would be. Tried sizeof(end), but this cropped off last two lines for some reason. So using 100 at the moment. This sort of works, but I think it also adds some new lines or null-terminating characters in the end or something like that, because data parser cannot parse the modified data after that.
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Mar 21, 2013
Working on a program that converts infix to postfix math formulas. Ive successfully converted the infix to a postfix notation but now i am having trouble solving the equation from the postfix form. Im trying to set a result equal to three variables as shown below:
result = op1 ch op2;
where op1 and op2 are numbers and ch is the operator (+-*/) depending on what the user entered into a string. The error im getting is that it expected a ";" before postfix so clearly it doesn't understand what im trying to do. how to put the answer from op1 ch op2 into result.
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Apr 1, 2015
#include<iostream>
#include<vector>
#include<map>
using namespace std;
class foo {
struct type {
int i;
string s;
}y;
[Code] ....
In the sample code
1) why can't we use union if its members have constructors
2) I am not able to insert in Map.
3) also I am not able to use object of struct type y to assign value of its members and later push_back in vector
I am getting following error
knils@knils-HP:scott_mayers$ g++ vector_of_struct.cpp
vector_of_struct.cpp: In member function ‘void foo::fun() const’:
[Code] ....
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Apr 14, 2013
How can i solve a problem of sin(x) without using any math.h and only using my own declared function.
#include <stdio.h>
int fact (int a) {
int i;
int k = 1;
for (i=1;i<=a;i++)
[Code] ....
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Jan 16, 2014
#include "stdio.h"
char t[16] = {0x8F,0x78, 0xC6, 0x12, 0xBA,0x98, 0xA2,0x16, 0x8F,0x78, 0xC6, 0x12, 0xBA, 0x98, 0xA2, 0x16} ;
char w[44];
void main(){
for(int i=0 ; i<4 ; i++){
w[i] = (t[4*i], t[4*i+1], t[4*i+2], t[4*i+3]);
printf("%0x ",w[i]);
}
}
i want to put some elements of the t array into the w array but when i do this, it prints only t[4*i+3]
i want the output to be something like this
w[0] = t[4*i], t[4*i+1], t[4*i+2], t[4*i+3] = 0x8F,0x78, 0xC6, 0x12
w[1] = 0xBA,0x98, 0xA2,0x16
and so on
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Nov 4, 2013
Here is my objective: Write a c program that calculates the value of a mathematical expression comprised of positive numbers and the operations "+" and "-" . Specifically, first prompt the user to input an expression, read itin as a string, and then print the value of the expression. You may assume that the expression does not contain spaces, maximumsize of the expression (including digits and operators) can be 20,and that all numbers are single digit numbers.
Note that, the digits would be read in as characters; you will need to translate them to numbers (recall the ASCII table). Implementation Requirements:
Write a function called "evaluate" that takes as input a mathematical expression(as a string) and returns the value of the expression. The prototype of the function is: intevaluate(char expr[]);
Sample Output:
Input: 4+2-1+7 Output:12
Code:
int main()
{
char expr[21];
int a,ssum;
printf("Input: ");
scanf("%20s", expr);
[Code] .....
the program runs, but the output is not coming out correct.
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Mar 22, 2013
I am new to c programing and I had spend 2 days on a program and I can't fix the error:
Code] ....
gcc Test.c -o Test.exe
/tmp/ccZkbk0V.o: In function `f':
Test.c:(.text+0x2f): undefined reference to `sqrt'
collect2: ld returned 1 exit status
Tthe program I am working in is:
#include <stdio.h>
#include <math.h>
int f(int x){
return (sqrt(4.0 - x*x));
[Code] .....
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Dec 22, 2013
Is there any way to do date math using standard C libraries? I looked around in the time.h but didn't see what I needed.
What I need to do is be able to add a certain number of minutes to a date and have it give the current date/time. For example, add 15918765 minutes to 01/01/1980 00:00 and have it tell me 04/07/2010 4:45PM. I really don't want to write this myself or go platform-specific.
Does this exist somewhere or am I SOL?
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Jan 27, 2014
For some reason, my input seems to lag one behind when inserting data. Attached, I have code that I wrote along with the example of the lag. What may be wrong with my code that is causing this to lag?
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Apr 30, 2013
I wrote a program that solves an equation of two numbers, but in addition to that, I want it to be able to continue to solve longer equations. Ex: ( solves 2 * 4, or 2 * 4 - 5).I want to put this part of the program's result into a variable and go from there. How do I place the result of the calculation into a variable, and where would it go?
Code:
#include <stdio.h>
#include <string.h>
int main(void) {
int a;
scanf("%d", &a);
char s[2];
scanf("%s", s);
int b;
scanf("%d", &b);
}
[code]....
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Oct 14, 2013
I am trying to compare a math operator with a variable, but i keep getting this error:
postfixDriver.cpp:93: error: expected primary-expression before ')' token.
I'm sure it's probably something simple, but im just not seeing it. Here is the code snippet:
while (strlen(str) != 0) {
split (str, token);
Postfix stack;
double a;
double b;
double answer;
if (atof(token)==0.0)
[Code] .....
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Jan 8, 2013
I want to use a dataset of type set which will have the type pair<char,string> or pair<string,string>. How can i insert values into the set, because i have to initialize the set and will not change the set during the program.
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Dec 17, 2013
I am trying to convert decimal value 1 to 32 to hex value and insert it at 4th pos of char array and send it as hex value at the serial port .
My issue is it is converting to decimal to hex value but when it sends, it treat the converted hex value as char and sends it equivalent hex value.
For example
if decimal =1 then its hex = 1.
so , writebuffer[3] =1
But when we send whole writebuffer through send function, it treat this 1 as char and sends its hex value as 31. how to send its hex value.
unsigned int i=0;
char hex[3];
unsigned char hexunsigned[3];
unsigned int dec;
do {
unsigned char writebuffer[8] ={0x01, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
[Code] ....
The send function is
void serial::send(unsigned char data[], DWORD noOfByte) {
DWORD dwBytesWrite;
WriteFile(serialHandle, data, noOfByte, &dwBytesWrite, NULL);
}
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Nov 19, 2013
I have the structure defined in the code below and need to insert a new string into the middle of the string array. I know there is a way to insert a new element with a vector. How to do this. I have tried several variations similar to uniqueList.word.insert(400,"disisdabomb"); but with no luck.
const int maxWordCount=1500;
struct wordCountList
{
string word[maxWordCount];
int count[maxWordCount];
};
wordCountList uniqueList;
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Mar 28, 2014
I'm trying to insert a structure into a binary file, then read it back out into a "temporary" structure and output some values.
#include <iostream>
#include <fstream>
using namespace std;
struct b_tree_node {
int num_keys; // number of keys in this node
int key_val[3]; // key values (0 to num_keys - 1)
int child[4]; // child file addresses (0 to num_keys)
[Code] ....
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Feb 11, 2014
math part.
The equation I need to use is: payment = [(rate * (1 + rate)^number payments ) / ((1 + rate)^number of payments -1)] * loan
Also, the value of rate in the above equation is (interest/12)/100. So 12% annual interest would be 1% monthly interest.
heres my code:
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
[Code].....
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May 21, 2014
I'm having trouble with getting a sine function to work. All variables are defined earlier in the same section. I have the code in a button (where I figured it would go) but I get the following error:
WindowsFormsApplication2.Math does not contain a definition for 'Sin'
For reference, I am using Microsoft Visual Studio Express 2013, and am coding a Windows Forms Application.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
[Code] ....
I've tried other functions as well (abs, sqrt, etc.) to no avail, as Math only seems to pop up with two options: Equals and ReferenceEquals.
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Aug 17, 2014
I have to create a program that read two numbers and the math operators +, -, * and /. After that I should print the operation required. But I tried to declare a <symbol> variable as char type, without sucess...
Here goes my script:
float num1, num2, result;
char symbol;
printf("Write two numbers:
");
[code]....
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Feb 17, 2013
I'm trying to make a function that lets me pass an index and a string and will insert the string at that index in the linked list...
Code:
typedef struct node {
char* value;
struct node* next;
} LinkedList;
void llAddAtIndex(LinkedList** ll, char* value, int index) {
[Code] .....
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Sep 3, 2013
Its a basic math function using the exponential growth formula which is correct but the computer is not outputting the right numbers.
Code:
#include <stdio.h>
#include <math.h>
int main() {
int blanketsquares, num1, num2, blanket,remainder;
[Code] .....
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Sep 7, 2014
I want to insert an element into binary tree using pointer passing through functions. In my program i have used three structure which are follows :-
Code:
struct tree{
int data1;
struct tree *leftptr;
struct tree *rightptr;
};
struct list{
struct tree **data;
struct list *node;
[Code]...
Here i think problem is in allocating memory to n2 . why i do this because i want to store the address of address of left and right pointers of tree and extract that address to get the address of left and right pointers. Is my method correct ?
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