C :: Array Of Functions Declaration / Definition And Call
Aug 3, 2013
i am using c language to program PIC micro controllers, i am making a multi compilation unit project in order to organize my code better.
I want to create an array of functions and be able to call it from anyplace in the code
what i have done so far gplib.c
Code:
typedef void (*out)(int8);
void OUT_A(int8 weight){output_A(weight);}
void OUT_B(int8 weight){output_B(weight);}
void OUT_C(int8 weight){output_C(weight);}
void OUT_D(int8 weight){output_D(weight);}
void OUT_E(int8 weight){output_E(weight);}
out output_port[5+1] = {OUT_A, OUT_B, OUT_C, OUT_D, OUT_E};
how to declare them in gplib.h and how to call them anywhere in the code.
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May 11, 2013
I read that Memory is allocated during definition of a variable and not during declaration. Declaration is something like,
Code: int x;
And definition is assigning some value to it. This is what my professor taught. My doubt is if memory is not allocated during declaration, then how the compiler successfully compiles and runs the following, which i had already tried.
Code:
#include<stdio.h>
#include<conio.h>
int main() {
int c;
int *p=&c;
printf("%x",p);
getch();
return 0;
}
The variable c is only declared. But the program outputs a memory address. Shouldn't it show an error?
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Dec 17, 2013
is possible to combine structures declaration and definition in programming language?
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Jan 11, 2014
Why I take warning on this code :
Code:
#include<stdio.h>
extern int v = 0; // Declaration and definition of an external
int main(void)
[code]...
Is there any error? Why I take a warning: 'v' initialized and declared 'extern'|||=== Build finished: 0 errors, 1 warnings ===| ???
and what is the meaning of :An extern declaration that initializes a variable serves as a definition of the variable. This rule prevents multiple extern declarations from initializing a variable in different ways.
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May 12, 2013
I am just learning using class template but I keep getting error unable to match function definition to an existing declaration
template <typename T>
class Homework {
private:
string name;
public:
template <typename T>
void SetName(T val);
[Code] ....
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Apr 13, 2013
I've written the following code and keep getting the errors:
Error1error C2244: 'Supermarket<temp>::operator =' : unable to match function definition to an existing declaration
Error2error C2244: 'Supermarket<temp>::setName' : unable to match function definition to an existing declaration
Error3error C2244: 'Supermarket<temp>::setArea' : unable to match function definition to an existing declaration
#ifndef SUPERMARKET_H
#define SUPERMARKET_H
#include<string>
#include<iostream>
using namespace std;
[Code] .....
I moved the files to the .h file, and now I'm getting
Error2error LNK1120: 1 unresolved externals
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Jan 3, 2014
#include "stdafx.h"
#include <iostream>
#include <math.h>
using namespace std;
class Calc {
[Code] ....
when i built it, it showed the following errors:
1>------ Build started: Project: rough, Configuration: Debug Win32 ------
1> rough.cpp
1>e:c programs
ough
ough
ough.cpp(17): error C3872: '0xa0': this character is not allowed in an identifier
1>e:c programs
[Code] ....
Need sorting out the errors!!!
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Dec 24, 2014
We had few functions which were written in Java, and we are now moving to C# .Net.
Instead of re-writing the code in .net, I want to know if there is any possibility to use those functions in .Net as is. (calling java functions).
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May 26, 2013
Here is a working C++ program and its output that reads the names of a certain number of functions whose names are written in a disk file that provides the control parameters in a near-real time fashion. Based on this information, the program calls those functions whose names were given in this text file as parameters. The method I have used is to build a map of functions that connects the names of the functions to the actual functions. Once this map is created, then it is very easy to iterate in such a way that only those selected functions are called.
So far this is working well, and it makes the logic of the code easier because ultimately there will be a large inventory of functions (probably hundreds of functions), and this way of pre-building a map of functions avoids writing hundreds of if statements in the code. Of course, pre-building this reusable map in the background is still equivalent to writing that many if statements, but at least it makes the code very compact and much more automatic, since it is done only once.
But I now have a related question: In this case (when the selected subset of functions to call is given as incoming data as in this example), does C++ make it possible to avoid using maps of functions, by directly applying the string variable that holds the name of the function in order to call the original function immediately For instance, if a string variable s = "MyFunction", then is there a more direct way of using this string as if it were the actual function whose name is spelled exactly in that way? This would make the code even more compact.
Here is the sample test code for the map of functions, and its output:
First of all here is the text file "FileForNamesOfFunctions.TXT" that contains the part of the "data", which is the set of functions select from from the inventory and only call these:
Code:
function2
function3
function5 And here is the C++ code that uses this "data":
Code:
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
[Code] ....
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Sep 27, 2014
This week we are learning to use templates, and I don't understand how to call my member functions with my template based class. I tried the standard convention of calling member functions, but I keep getting an error saying name following"::" must be a class or namespace name. I'm thinking my problem lies with my typename T, but I am unsure. Line 16 is where I am getting tripped up.
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
template<class T>
T Set
{
public:
[Code]...
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Sep 14, 2014
I want this programming to call functions choose between a customer type and call the relevent function to calculate the final price but it is not calling the functions.
#include <iostream>
using namespace std;
double amount;
double studendOrPensioner(int&choice, double &origPrice);
double OtherCustomers(int&choice,double& origPrice);
[Code]...
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Jan 7, 2013
I would like to know the difference between the following two forms of array declaration:
(1)double myArray[3] = {1.0, 2.0, 3.0};
(2)array<double,3> myArray = {1.0, 2.0, 3.0};
If I say the second one allows to use different functions like .begin(), am I right? Is there any other difference between these two declaration?
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May 3, 2013
At the moment im trying out with pointing to an array of functions. I got this working as following:
typedef void (* functionPtr) ();
functionPtr functions[2][2]={{do11,do12}, {do21,do22}};
void do11(){DEBUG_PRINTLN("11");}
void do12(){DEBUG_PRINTLN("12");}
void do21(){DEBUG_PRINTLN("21");}
void do22(){DEBUG_PRINTLN("22");}
void loop(){
A=0;
B=1;
functions[A][b]();
}
But now I'm trying to use this to point to a function inside a class so instead of do11, i want to be able to point to Basic.Do11. Somehow this doesnt work and I keep on getting this message:
error: argument of type 'void (Basic::)()' does not match 'void (*)()'
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Jan 24, 2014
I want to understand the ways in which arrays can be declared and used. What each of the following do or what's the difference between them and what would be the length of each:-
1 - char ary1[50];
2 - char ary2[50] = {'H','e','l','l','o'};
3 - char ary3[50] = {'H','e','l','l','o',' '};
4 - char ary4[50] = {' '};
5 - char ary5[50] = {' ','H','e','l','l','o'};
6 - char ary6[50] = {' ','H','e','l','l','o',' '};
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Jan 19, 2014
I have a little program that does some statistical processing on text files. The program has thrown a segmentation fault with an input file that is larger that I have used before. I didn't write this tool, so I went searching for the problem. Data from the input file is dumped into a 2D array and the program fails at the declaration of that array.
Code : double A[cont][Nr_col_split];
The vales for cont and Nr_col_split and determined from the input file and in this case, cont=807 and Nr_col_split=350. I assume that these values are just too large and not enough memory can be allocated, or something like that. Do I need to use reserve or similar to set aside enough memory? I will have input files that are quite a bit bigger than this one, so perhaps there needs to be a different solution for storing the input file data.
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May 5, 2014
I was going through a code where i found the definition of int array[63] in one of the source files. But i also found the declaration as extern int array[66] in another source file. This is clearly wrong, but my doubt is how the compiler compiled it. It should have thrown error. In case if it compiles then what will be the behavior of the system? Will it be normal or some undefined behavior?
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Jul 14, 2014
I have some files:
file1: 1000x500 array of numbers
file2: 2000x600
file3: 300x5000
...
I would like to automatically declare array variables of myarray1, myarray2, myarray3... that reads the numbers from files:
Code:
for (i1=0; i1<nrows; i1++)
{
for (i2=0; i2<ncolumns; i2++)
{
fscanf(filename, "%lf", &y);
myarrayX[i1][i2]=y;
}
}
nrows and ncolumns can be passed from a config file. Also I can cat all files into a single filename. However, the difficult part is:
How to declare different myarrayX automatically ? (A workaround is to declare a huge 3d array but I do not want to do this).
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Jan 30, 2013
I am attempting to declare an array of pointers dynamically based on user input. I am not sure if A) I'm implementing the syntax of declaring a dynamic array correcntly and B) if my code is set up correctly to print otherwise.
int array_size;
cout << "Please enter the size of the array: " << endl;
cin >> array_size;
if(array_size >= 8) {
cout << "Invalid array size, please enter a valid integer size";
cin >> array_size;
[Code] .....
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Mar 28, 2013
I'm having trouble declaring and initializing a two-dimensional array using the C++11 standard conventions. I would like to know how to do it in C++11 style as know how to use the old style.
the exception im getting is:
c++11_array_exp.cpp:37:3: error: too many initializers for ‘std::array<std::array<std::basic_string<char>, 6ul>, 22ul>’
you can find my code here:
[URL]
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Jan 23, 2014
Here's my program: - Program which inputs a string from user, reverses it and displays it.
#include <iostream>
using namespace std;
void string_reverse (char [], const int);
int main() {
const int arraysize = 10;
char string[arraysize];
[Code] ....
In the string_reverse function, I have declared temp character type array but on line 38, the
compiler is throwing 3 errors: -
error C2057: expected constant expression
error C2466: cannot allocate an array of constant size 0
error C2133: 'temp' : unknown size
I have declared a constant integer arraysize in line 35. Now I have no clue why is this happening because I think as I have declared it as a constant integer variable, this should not happen.
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Feb 2, 2015
I'm writing code to create an array of integer and let user input choice to display, replace, add new element, etc.I created a header file in the header file there's a function:
Code:
int display_one_element(int* array, int num_of_elements, int position) {
if(num_of_elements < position || position < 0) {
printf("Position out of bound.
");
return 1;
}
return array[position-1];
}
in main I write a function call:
Code:
display_one_element(array, *p_num_elements, position);
My code seems to work fine but there's an error message right next to my function call:
1.too many arguments provided to function like macro invocation
2.Expression result unused
I tried to move the function from header file to c source file. but other functions in the header file works fine and this doesn't work with the error message.
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May 3, 2013
Your program will declare a 2-D array of dimensions 20 x 20. The array will be of type "character".
Functions: You will create several functions for this program.
1) One function will take the address of the array and initialize all cells to ' ' (a blank space).
If the 2-D array is odd, then you will create functions that make:
2) a triangle using '*', OR
3) a diamond using '*', OR
4) a bulls-eye using '*'. <=== this one is worth BONUS POINTS!! and is therefore optional.
If the 2-D array is even, then you will create functions that make:
5) checkerboard #1 using '*', OR
6) checkerboard #2 using '*', OR
7) a GIANT checkerboard using '*'. <=== this one is worth BONUS POINTS!! and therefore is optional.
These functions will be called from main, and return nothing. Your program will keep asking the user if they want a different kind of 2-D array and different shape. If not, then quit.
Here is what I have so far. I have only been able to get the triangle work. I have not attempted the bullseye or giant checkerboard as they are for extra credit and I can't get the main program to work.
#include <cstdlib>
#include <iostream>
void clear(char pattern[20][20]);
void triangle(char pattern[20][20], int size);
void diamond(char pattern[20][20], int size);
// void bullseye (char pattern[20][20], int size);
[code]....
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Jan 22, 2015
I want to declare a global array and then use it in a few functions. When I want to assign any number to that array I face with this error:
Code:
a.c:11:6: error: expected expression before ']' token
n[]={1,2,3,4,5};
^
The code is:
#include <stdio.h>
int n[5]; // I need to define the array here to be global
int main () {
n[]={1,2,3,4,5};
[Code] .....
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Sep 5, 2014
What "int values" is supposed to mean as parameters to these functions? I'm not sure what do with them. Also how to input values into the array via functions. I was trying to but I just don't understand how to connect a user's input to a function to then enter into an array.
// input reads “values” integers from the user to place in the array data. It prompts the user for each value individually with the ordinal position of the value.
void input (int data [size], int values);
// Places the sum of corresponding values from arrays a and b and places the results in array s. The first “values” integers in the array are processed.
void do_sums (int a [size], int b [size], int s [size], int values);
[Code]...
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Mar 9, 2015
I keep getting an unresolved external symbol error in the double GetHighest function. Ive looked over the code many times and can figure out why its giving me this error.
//Question 1
// Copy source code below and save to a .cpp file (say lab11_01.cpp) and write statements to print what is indicated in the source code.
//In this question, you will implement code for finding the highest value in an array, and you do this in a function.
//This program gets a series of test scores and calculates and display the highest score.
#include <iostream>
#include <iostream>
#include <iomanip>
using namespace std;
// Function prototypes
void getTestScores(double[], int);
double getHighest(const double[], int);
[Code] ....
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Oct 4, 2014
Trying to make a program that stores a sequence of integers in an array by using functions. This is my code so far:
# include <iostream>
using namespace std;
int Sequence_Length(int seq_length)
{
[Code]....
I get an error in the main, not completely sure how to "call" functions to the main..
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