C++ :: For Loop To Find Vector Length
Jul 21, 2013
Ok my assignment has me doing vector math with some canned code provided for me by the instructor This is the header file to the class I'm working with and the .cpp file as far as I've gotten it.
#pragma once
#include "Scalar.h"
class Vector2D {
public:
Vector2D();
Vector2D( const Vector2D& ) ;// copy constructor
Vector2D( Scalar element[2] ) ; // initialize with an array
[Code] ....
I'm having trouble seeing which data members I'm multiplying together and what the initial state, continuing state, and after loop action I'm supposed to be using in the for loop.
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Jan 29, 2015
I need to be able to find every possible permutation using all possible values of a char. But I have to make it be able to form permutations from a length of 1 to variable N. For example, if N=3, I need it to be able to come up with
0x00
0x01
.......
0x00 0x00
0x01 0x01
.......
0xff 0xff 0xfe
0xff 0xff 0xff
How could I do this. (I would like to avoid recursion, since N might be as large as 50 or 60 and using recursion would most likely cause a stack overflow)
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Jul 6, 2014
int t;
string a;
cin>>t;
getline(cin,a);
int len=a.length();
cout<<a<<" "<<len;
[code].....
why is the length 0?what can I do to get the correct length of the input string?
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Dec 15, 2014
I am stuck here.
printf(" Enter a line of Morse Code for decrypting");
scanf("%s",phr);
len=strlen(phr);
for(a=0;a<36;a++) {
if(strcmp(phr, morse[a])==0)
printf("%c", alpha[a]);
};printf(" ");
The output :
[output] Enter line to encrypt:
..... -.... --...
converting...
5 [/output]
It should read all code, including null. between coded letter one space, between coded word three spaces.
The output should be:
[output]
56 7 [/output]
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Sep 25, 2014
I am working on a c-programm. In this program I have to convert the amount of money I read on two variables into the corret format. I got Euros and cents on 2 ints. But now I want to add both of those variables in a String (char array). Also i want to find out the length of the new char array.
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Jul 24, 2014
I'm trying to find vertical paths of length n through a 2D grid of numbers. Paths may connect orthogonally or diagonally. An example grid and an example possible path looks like this:
//Grid
0 1 2 3 4 5 6 7
0 2 4 6 4 1 3 4 5
1 5 3 5 8 6 6 6 6
2 3 4 2 1 1 2 5 3
3 3 2 3 3 1 3 4 5
4 3 6 1 1 5 2 5 4
5 2 5 4 2 4 5 6 2
6 6 6 1 1 5 1 4 5
7 1 5 6 4 2 4 2 3
A example possible path of length n = 3 is running from (3,2) to (3,4) - All 1s ...An example of n = 4 is the run of 3s (1,1) (0,2) (0,3), (0,4)
What is an efficient algorithm for solving this kind of problem? I would like to solve (ideally) millions of grids, giving a list for each grid of all possible paths of length for n = 3-6.
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Feb 13, 2015
I have a question about finding the length of first sentence in an input string.
For example, let the input string be: dream in code. community learning
The length of first sentence is 13 (blanks are included). My question is how to create conditions for multiple punctuation signs (!,?)? If while loop goes like:
while((str[i]!='.')||(str[i]!='!')||(str[i]!='?'))
it gives me an error for infinite loop.
Code:
#include<stdio.h>
int main() {
char str[100];int i=0,br=0;
printf("enter a string:");
gets(str);
[Code] ....
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Jan 5, 2013
When I use vectory.push_back(obj), if the length is out of reserved bound, it will deallocate the whole vector and reallocate a big piece of memory. From my understanding I think c++ only allocates 1 more place for the new obj. This is quite inefficient. Is there a way to set the step length whenever the size is out of bound? e.g. 50 more spaces.
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Jul 10, 2013
The error is unclear but suggests Its received a bad pointer from another heap. It references dbgheap.c line 1322 and assertion failure
I have two string vector functions the first is called from the main function, the second is called from the first.
Their purpose is to receive a string of text and numbers in a semi-specific format, which the main body of the code reads from a text file, and delaminates the data as to return the first variable in the string as the variable name and the second as the variable value. Along the way it filters out a lot of the unwanted whitespace and punctuation.
E.g "{ VariableNameA 123 }" would be returned as "VariableNameA" And "123"
The code works perfectly for most of the lines in the text file but fails on one particular line where the first variable is 25 characters long. Basically it works for anything 22 characters or less. There are never more than 4 elements in the vector and each element is never intended to be longer than 25 characters.
It fails trying to return from the second split function to the first split function.
Is there a limit to the size of each vector element? I'm struggling to find a way round this without having to rewrite the whole thing.
vector<string> split(const string &s, char delim) {
vector<string> elems;
split(s, delim, elems);
return elems;
[Code] ....
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May 22, 2013
I am writing a raytracer, and currently I'm working on creating a bounding volume hierarchy to accelerate the process. To do this, I am first creating a vector that holds each of the objects in the scene, and passing this vector to the constructor for my BVH.
Code:
//in header
BVH_Node* bvh;
//in main raytrace function
[Code] .....
I am testing a scene that has only 2 objects, and so it goes to the size == 2 check. The first time it hits makeLeaf(), I segfault. I've used both gdb and valgrind, and of course it's a memory mapping error. gdb's backtrace tells me that the length of the vector I've passed in is -805305610 and the capacity is -21, and that it is inside my makeLeaf() function that the error occurs.
Here's the function:
Code:
BVH_Node* BVH_Node::makeLeaf(GeomObj* v){
BVH_Node* node;
node->obj = v;
node->isObj = true;
return node;
}
The segfault happens at
Code: node->obj = v;
If I run my raytracer without a BVH, the objList works perfectly.
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Jul 5, 2013
I have asked a related question before, and it was resolved successfully. In the past, when I wanted to use std::max_element in order to find the maximum element (or even sort by using std::sort) of a vector of structures according to one of the members of the structure, all I had to do was to insert a specially designed comparison function as the third argument of the function std::max::element. But the latter comparison function naturally accepts two arguments internally.
For instance, here is a test program that successfully finds the maximum according to just one member of the structure:
Code:
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
[Code] ....
And the output was this, as expected:
Maximum element S.a of vector<S> vec is at: 9
[I]max element of vec.a between slot 3 and slot 6 is: 6, and its index is: 6 vec[6].a = 6
[I]max element of vec.a between slot 4 and slot 7 is: 7, and its index is: 7 vec[7].a = 7
[I]max element of vec.a between slot 5 and slot 8 is: 8, and its index is: 8 vec[8].a = 8
[I]max element of vec.a between slot 6 and slot 9 is: 9, and its index is: 9 vec[9].a = 9
However, I now need to search and find an element of vector<myStruct> according to just one member of myStruct, instead of finding the maximum or sorting as before. This presents a problem because the function std::find does not accept such a comparison function as its third argument.
This was the description of the std::find function that I found: find - C++ Reference
Code:
template <class InputIterator, class T> InputIterator find (InputIterator first, InputIterator last, const T& val);
I could also find another function called std::find_if, but this only accepts a unary predicate like this: find_if - C++ Reference
Code:
template <class InputIterator, class UnaryPredicate> InputIterator find_if (InputIterator first, InputIterator last, UnaryPredicate pred);
And once again this is either inadequate of I don't see how to use it directly, because for the third argument I would like to insert a function that takes two arguments with a syntax like this:
Code:
int x=7;
std::vector<S>::iterator result;
result = std::find(vec.begin(), vec.end(), []( const (int x, const S & S_1) { return ( x == S_1.a ) ; } ) ;
Is there another std function that I can use to make search and find an element according to just one member of myStruct?
Or perhaps there is a clever way to pass two arguments to the unary predicate.
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Aug 10, 2013
For example let say there is vector [1,2,3,4,5,6,7,8,9] and let say there is int n
if i say n=3
I want to find all possible 3 combination
[1,2,3][1,2,4].....such and such
if i say n=4
[1,2,3,4][1,2,3,5]......
I want to know how you write the code depend on the input n. Is it call dynamic programming?
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Oct 15, 2013
So the program reads contents from a text file into a vector and then the user enters in a string that they want to search for. The program iterates through the vector to find the string and then saves that line to another vector to display later(incase there is more then 1 instance of the string found).
Here is what I have atm:
void doSearch(vector<string> &phonelist, string searcher, vector<string> &holdNumbers)
{
int i = 0;
string value;
[Code].....
I just get an R6010 error -abort() has been called.
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Feb 16, 2015
Im currently trying to find the mode of a vector through a map but am not sure how to do so besides the attempt ive made
void mode(vector<double>v)
{
map<double, int> map;
[Code]....
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Sep 4, 2013
I defined the following function to find out the iterator of a certain value in the vector. I defined it as such so if the value exist in the vector then return a iterator of it, if not then return a pointer pointing to nonsense.:
vector<tIndex_t>::iterator unlabelTit(const tIndex_t index) {
for(vector<tIndex_t>::iterator it=unlabelT.begin(); it<unlabelT.end(); it++) {
if(index==*it) return it;
} return NULL;
}
But looks this one is not accepted by compiler, saying I cannot do this kind of comparison like:
unlabelTit(i)!=NULL;
so I just delete the return NULL; and then the compiler giving me warning about no return statement before }.
a pointer pointing to nonsense? how to do that?
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Dec 14, 2014
I have this class I have been working with,
Code:
// objects to hold results, row id, and name
class result_holder {
public:
// initialize class members
result_holder() : row_id(0), row_value(0.0), row_name("") { }
[Code] ....
There are cases where I need to find an object based on the value of row_id and delete the object from the vector row_results. I could find the proper object by looping through the vector and testing against each member.
Code:
// id I am looking for
unsigned int id_to_delete = 12;
for(i=0; i<row_results.size(); i++) {
if(id_to_delete == row_results[i].row_id) {
delete row_results[i];
}
}
I have used find before to find the position in a vector with a specific value, but I don't know how to use find to locate a specific value for an object member.
Also, is delete what I need to get rid of the object or should I be using erase as in,
Code:
// id I am looking for
unsigned int id_to_delete = 12;
for(i=0; i<row_results.size(); i++) {
if(id_to_delete == row_results[i].row_id) {
row_results.erase(row_results.begin()+i);
}
}
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Sep 14, 2014
What i need it to do is ask the user for a number of cases. The user will input numbers and the program should add the inputs until zero or a negative number is entered and then out put the average of those inputs. The amount of cases is pretty much how many times an average will be done. so if the amount of cases is 4. and the inputs are 1,3,(1+3/2)0 then it should output 2. and that would be ONE case, next inputs are 5,6,4,0(5+6+4/3) the output is 5 and that is case two. etc.
Here is my code:
#include <iostream>
using namespace std;
double avgVal(int, int);
int main() {
int amountOfCases;
cin >> amountOfCases;
int* numbers = new int[amountOfCases];
int input=0;
[Code] ....
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Nov 18, 2013
I'm trying to sort my vector, find duplicate values using unique and erase them. Program can compile successfully but the duplicates are not removed.
output:
x: 3
y: 2
x: 6
y: 4
x: 3
y: 2
vector<Point2D> p2dvector;
void readData()
[Code].....
I also have operator== in my Point2D class which I understand it is required to use unique for vector.
bool operator==(const Point2D& lhs, const Point2D& rhs)
{
return lhs.x == rhs.y;
}
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Oct 12, 2014
Okay, so for an assignment I need to write a function called find() that returns a reference to a vector. So I have vector <int> & find(string & key); If I do this, I get the obvious warning warning: reference to local variable 'lineNum' returned [enabled by default].
If I do vector<int> & find(string & key) const; I get a huge error that starts out like
In member function 'std::vector<int>& index_table::find(std::string&) const':
indextable.cpp:74:30: error: no match for 'operator='
Am I using the const identifier incorrectly?
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Dec 31, 2012
I want to build a server which holds hundreds of thousands of active users in memory. To keep all the users organized i would like to store them in a Vector.
The problem is how i could quickly and easy find the object whenever i need it? All users will have a unique ID. Would it be possible to keep some form of a Vector Index on the unique id number?
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Mar 4, 2015
This program is to solve a word maze and find the number of words in the maze from a dictionary file.
The program runs, but stops by finding 1,2 and 3 letter words.
#include<iostream>
#include<vector>
#include<fstream>
#include<algorithm>
#include<string>
using namespace std;
int main() {
vector <string> dict,forward,reverse;
[Code] .....
I also tried to find words using the entire vector as a container, the synopsis code that also did not work is below
while(j<dict.size()) {
if(dict[j].size()>2) {
if (std::find(forward.begin(), forward.end(), dict[j]) != forward.end()) {
cout<<"found word "<<dict[j]<<endl;
[Code] ....
Attached File(s)
dumpling2.txt (2.54K)
Dictionary.txt (718.34K)
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Nov 25, 2013
how i can find the 5 without loop?
vector<int>i;
vector<int>j;
i.push_back(1);
i.push_back(2);
j.push_back(3);
j.push_back(4);
j.push_back(5);
[Code]...
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Mar 22, 2013
For a beginners C++ lab, I have a base class Employee and two derived classes HourlyEmployee and SalaryEmployee. In main, I have a vector defined as vector <Employee *> VEmp; It's then passed to a function to get the input, which works fine. But what I'm struggling with is another function with the header "printList(const vector <Employee *> & Ve)". It's supposed to loop through the vector and call the appropriate printPay function, which is a seperate print function inside each derived class. How do I loop through the vector and print it out? I was trying to do a for loop and something like "Ve[i].printPay();", but that doesn't work. So how would I do it?
Here's some snippets of the relevant code.
class Employee {
....
virtual void printPay() = 0;
};
class HourlyEmployee : public Employee {
[Code] ....
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Feb 14, 2013
i have a paradigm where a integer before gets enqueued to a queue, the loop of queues in a vector is searched and integer is enqueued to a queue which has minimum size among the queues. the following code shows the operation.
#include <vector>
#include <queue>
std::vector<std::queue<int> > q
int min_index = 0;
std::size_t size = q.size();
for( i=0; i<size; i++){ //accessing loop of queues
if(q[min_index].size() > q[i].size())
min_index = i; // Now q[min_index] is the shortest queue}
q[min_index].push(int)
next i am trying to extend my paradigm with that the condition the integers should be enqueued to the shortest queue until it becomes maximum size among the queues.
do{
q[min_index].push(int)
} while(q[min_index].size > queue sizes in the vector loop except this queue )
how to search the loop of queues of vector in the while ()
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Jul 12, 2014
How would I make a loop that would simultaneously compute both the max and min of a vector?
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Oct 13, 2014
Lets say that i have the coordinates of a 2D space (x and y), I want to store the coordinates as x and y in a vector to find the nearest neighbor of given points like i have:
#3.57 3.18#
#84.91 27.69
#93.40 4.62
#67.87 9.71
#75.77 82.35
#74.31 69.48
#39.22 31.71
#65.55 95.02
#17.12 3.44
#70.60 43.87
Each coordinates is like x y and it shows points 1 to 10 (like 3.57 3.18 is point 1 in 2D space ). My question is that how i add all x and y coordinates in vector? I started like this;
`struct point{
int x;
int y;
[Code] ....
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