What is the correct syntax? I tried something like
Code:
class myclass {
multimap<int, void(*)()> mm_fn;
...
void afunction();
...
void anotherfunction(int anint){
mm_fn.insert(pair<int,void(*)()>(anint,afunction));
}
}
and the compiler does not like it.
Goal: To allocate some memory as a char*, read in some binary data, re-interpret it as a float* and then free the memory.
My code looks like:
void someFunction(float* &result) {
char * tmp = new char[1000];
//...Fill the char buffer here...
result = (float*)tmp; //Reinterpret binary data as floats
[Code] ....
Is the cast back to char* necessary on the red line (or could I have validly left it as float*)? Would it be different if I had written char * tmp = (char*)malloc(sizeof(char)*1000); on the blue line (and correspondingly used free (char*)floatData on the red line?
is it possible to alter the Pair function to make it use 3 elements?
View 13 Replies View RelatedI'm trying to call a function via a function pointer, and this function pointer is inside a structure. The structure is being referenced via a structure pointer.
Code:
position = hash->(*funcHash)(idNmbr);
The function will return an int, which is what position is a type of. When I compile this code,
I get the error: error: expected identifier before ( token.
Is my syntax wrong? I'm not sure what would be throwing this error.
I am running some simulation, in which i need to control the iterator of a multimap, like
multimap<double, int> mapp;
......
int n=6;
for(int i=0; i<5; i++) {
for(auto it = mapp.begin()+i*n; it!=mapp.begin()+(i+1)*n; it++) {
......
However this way of controlling is not possible for multimap. Why and how the make it work? Do I need to overload the operator +?
I have a multimap with over 300k entries defined like so: std::multimap<std::string, std::string> filedata;
Using the following code and std::multimap::equal_range, I am able to successfully search for a word in the multimap and get needed data:
// Data with strings.
data = std::vector<std::string>();
// Get iterators to matched pairs.
std::pair <std::multimap<std::string, std::string>::iterator, std::multimap<std::string, std::string>::iterator> dat = filedata.equal_range(word);
// Go through each matched pair and get needed info.
for (std::multimap<std::string, std::string>::iterator iter = dat.first; iter != dat.second; iter++) {
data.push_back(iter->second);
}
Now, I would like to search the multimap using regular expressions (EX: std::regex("[a-z][a-e]h")). What is the fastest way to do this? Example code may look like:
std::pair <std::multimap<std::string, std::string>::iterator, std::multimap<std::string, std::string>::iterator> dat = filedata.equal_range_with_regex(std::regex("" + word + ""));. Pseudo-code / algorithms will be enough.
I understand multimaps are key ordered. I have no problems with ints but when I put my char arrays in they are not alphabetically ordered. I must use char array and not <string>. Is it possible to alphabetically order them with char*
39 int c;
40 User *user;
41 char nameH[200];
42 char line[200];
43 int ageH;
44 double wH;
[code]....
I have created a multimap for my road points. The key refers to the road number and the values are vec3 points that make up the road.
I am trying to iterate through the values of each key point and create a road segment at each point on the road (except the last), adjust the values to be on the road points and then store them in a std::vector.
The RoadSegment constructor creates 6 vec3 points and pushes them onto a std::vector.
I have a segmentation fault in the line marked in bold
[for(mapIt = it.first; mapIt != it.second; ++mapIt)]
When i take out the lines creating the new objects and pushing them onto the std::vector it works fine.
std::vector<glm::vec3>::iterator SegIt;
for(int i = 0; i < m_genRoads->getKeyValueData().size(); i++)
{
int numberDesired = m_genRoads->getMultimapData().count(i) - 1;
[Code]...
I have an assignment to create a grading system using multimap. It's not completed yet at the moment but whenever i try to compile it tells me "no match for 'operator[]' in lines 56,57,etc. I
#include <iostream>
#include <string>
#include <map>
using namespace std;
class Student {
public:
//--- Constructor
Student (int id = 0, double gpa = 0);
[Code]...
I am attempting to implement function pointers and I am having a bit of a problem.
See the code example below; what I want to be able to do is call a function pointer from another pointer.
I'll admit that I may not be explaining this 100% correct but I am trying to implement the code inside the main function below.
class MainObject;
class SecondaryObject;
class SecondaryObject {
public:
[Code]....
How would i write a functor for this code. The code is written to read data from a file and store in a multimap.
The data has numbered lines. E.g.:
1 This is a string
2 This is a string too
So the aim is to store each word in the line with the number and then to enter a word to search for the line numbers it appears on. I do not know how to go about and write a functor
#include<iostream>
#include<sstream>
#include<fstream>
#include<cstdlib>
#include<map>
using namespace std;
int main() {
multimap<int, string>myMap;
[Code] ....
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.
View 3 Replies View Relatedint main()
{
int a=0, c, d, N, K;
bool stopBool = 0;
[Code]....
This is supposed to find take a number N and K and find all numbers between 0 and N that equal K and cout the number of pairs that fit it but it doesn't work.
here is a piece of my code:
while(T--)
{
std::vector<std::pair<int, int> > *dragon;
std::vector<std::pair<int, int> > *villager;
[Code]....
I now wish to print the elements of the vector. How do I do it?
I have tried to implement a much simplified version of boost::compressed_pair.What follows is a partially specialized EBO_pair<T1, T2> class template, written in C++11.The first type T1 is constrained to not be empty.The second type T2 may or may not be empty.
#pragma once
#include <memory>
#include <type_traits>
#include <utility>
namespace dsa
}
[code]...
Edit: added non-member swap() function template.
I have an assigment to make program which deletes from sentence all words with character count which is equal to pair number , for example - [ I like C ] and the result of this program should be [I C] because the word like contains 4 characters which is pair and it should be removed.
So I started writing my program and I am stuck at this block of code -
#include <stdio.h>
#include <stdlib.h>
main () {
char text[100], blank[100];
int c=0,d=0,i,j;
gets(text);
[Code] ....
To explain what is happening - I go through all string and search for first ' ' space symbol and check its value. If it is pair then my program prints that it is not pair[because last character before space had not pair number of characters], but the hardest part comes in when i have two not pair words , because space takes one character and now when i check if i%2 == 1 the answer is false [0] for the second word .
int example (int [], int, *int,*int,*int,*int);
int main () {
My code will be here
example (int array[], int size, &a,&b,&c,&d); // Like this??? I try it didnt work
[Code] ....
Find all the prime numbers between a given pair of numbers. Numbers should be read in from an input file called "numbers.txt" and find all the prime numbers between them. Store the prime numbers in an array, then sort the array from greatest to least. Display the array before and after the sort.
I'm stuck on how to put the prime numbers into an array.
The input file has the numbers 1 & 100.
Here's what I have so far.
#include <iostream>
#include <fstream>
using namespace std;
int main() {
ifstream fin;
fin.open("numbers.txt");
[Code] .....
I tried to use pointer with a function but I guess I am missing out on something
Code:
#include<stdio.h>
int add(int *a,int *b){
int *c,*d;
*c = *c+1;
*d = *d-1;
[Code] ....
And this one too
Code:
#include<stdio.h>
void add(int *a){
int *c;
c = c+1;
[Code] ....
I was wondering what magic does a * pointer before function actually do? Today our programming teacher asked us to look into it and explain it in the next class!
#include<iostream>
using namespace std;
int *binary(int []);
[Code].....
How can we assign a pointer to a function? const char* function_name(), here what exactly does the pointer point to?
View 4 Replies View RelatedCode:
void dereference(int* a, int* b)
{
a=b;
}
int main(int argc, char **argv)
[Code] ....
Why isn't f and d the same after calling "dereference(f,d);"
As the title says, i'm using a function which returns a pointer to a struct:
the struct is the following:
Code:
typedef struct POINT
{
uint16_t x;
uint16_t y;
}
Coordinate; the function i'm using:
Code:
Coordinate * Read_XTP2046(void)
{static Coordinate screen;
//calculations to determine the coordinates
screen.x=(temp[1]+temp[2])/2;
screen.y=(temp[0]+temp[2])/2;
// and so on...
return &screen;}
The question is: how do i catch this pointer and make it into a Coordinate struct in which i can read the x and y.
In my main program i would do the following:
Code:
Coordinate cor;
cor = Read_XTP2046();
This does not work, as the function returns a pointer, but how to transform this pointer into a Coordinate struct.
I would like to initialize an arry containing function pointers with adresses of functions that have a variable number of arguments.
Below the code that works in principle. I would however get rid of the warning message during compilation pointing to the initialzation of the funtion pointers in the array. How do I need to cast the pointers to the functions ?
Code:
gcc func_ptr_init.c
func_ptr_init.c:28: warning: initialization from incompatible pointer type
func_ptr_init.c:32: warning: initialization from incompatible pointer type
Code:
#include<stdio.h>
unsigned char func1_ptr(unsigned int* if_desc, int* result_code) {
*if_desc = 1;
*result_code = 1;
return(0);
[Code] ....
I am trying to return a pointer from a method. Below is a sample of my code.
CSubnode * CTest::GetSubNode() {
return m_psubnode;//this is declared in CTest as CSunbnode * m_psubnode
}
//in another class
m_subnode = m_ptest->GetSubNode(); //m_subnode is declared as a pointer
Is this the correct why to return a pointer?
I declared a pointer in main with value 0, so I want to change its value so that it points to other variable from a function, I guess the function creates a copy of my pointer that's why whatever I do within function doesn't change the real direction of the pointer in main. I've been trying something like this:
#include <stdio.h>
void redirectionate(char *str, char *ptrCopy);
int main()
{
[Code]....