C++ :: Setting The Value Of A Pointer From Function
Feb 20, 2013
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()
{
I need to set a function to a variable of some kind. Then later in the program it needs to run the function that is set to the variable. The variable doesn't need to change after it is set to a function, it just needs to be able to be set to a function. So maybe I don't need a variable? What do I do? :3 Is this even possible? :o
Example: if (PosRampYes == 0) { SomeVariableOrSomething = FirstFunction(); } else { SomeVariableOrSomething = SecondFunction(); } //later: SomeVariableOrSomething; //so if PosRampYes is set to 0 then this line would run FirstFunction()
I am having problems with setting up a menu as a function. The point of the menu is to display a list of 4 options and the user is supposed to choose one option and then the program will run. I am having trouble understanding how to display the menu once I run it because it is not working.
#include <iostream> using namespace std; int menu(int ans); // function declaration for menu void draw_triangle(int size, char ch); //function declaration for triangle void draw_downtri( int size, char ch); // function declaration for upside-down triangle void draw_diamond(int size, char ch); //function declaration for diamond
Need setting up counters for this program which should
Given a file of text, assume that a "word" is 1 or more consecutive, non-whitespace characters a "sentence" is a series of words terminated by either a period, exclamation point, or question mark
Design a C++ program (using functions/passing parameters) that will
-interactively prompt for and read the name of an input file -interactively prompt for and read a string to search for -open the input file (using an input filestream variable) and with one pass through the file -count the number of "words" in the file -for each word, make sure all letters, except the first, are lower case - leave the first character unchanged -count the number of "sentences" in the file -count the number of letters in the file (A-Z,a-z) -count the number of consonants in the file (consonants are letters that are not vowels - the vowels are: a, e, i, o, u, A, E, I, O, and U) -count the number of nonwhitespace characters in the file that are NOT letters -count the number of times the search string is found in the file (must be an exact match) - search for matches AFTER upper case letters have been coverted to lower case
I'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.
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
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 []);
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
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
How this code work bcoz when pointer variable assigned in called function and how different values get as resultant output, ans 2 97 for below code. How the code wil execute so that i can validate ans
#include <stdio.h> int main() { int i = 97, *p = &i; foo(&i); printf("%d ", *p);
I am trying to use "remove_if" with a predicate function inside a class. The code intends to remove the grid cells which an agent cannot move into (from among all possible cells).
That code would work if it was not in a class and the predicate was not a member function. However, now I receive long error messages which I guess refer to incompatibility of remove_if template with the predicate parameter (one error includes : error C2064: term does not evaluate to a function taking 1 arguments).
i need to pass myboard.board (board is in the class Cboard and it is an array of int) to a function in a class called piece however this is troubling . i need to pass it as pointer os that i could change its value here under is my code.
I am trying to wright a program that takes student grade data from a command line file, calculates a final grade, and copies the final grades to an output file. So far I have two functions, one that creates a student structure by allocating memory for it and returning its address, and one that should take that address and fill it with data from a line from the input file. My ultimate goal is to use a linked list to connect all the structs, but for now I just want to get the functions working. When I run what I have so far, I get an error C2440 (using visual 2010) that says "cannot convert from 'cStudent *', to 'cStudent', and points to the line where I call my fill function. How should structure pointers be passed?
I'm trying to pass the pointer of a dynamic array into a template function, but it keeps telling me there is no matching function to call because the parameters I'm passing in are wrong. how to make the function accept the pointer.
//main int main() { srand(unsigned(time(NULL))); int size; int *list; int *listCopy;
I'm having a problem understanding something with pointers. I was trying to pass a pointer into a function in MSVC-2013, like
char* charptr; and then calling myfunct(charptr);
and then inside the function i would set charptr equal to another char ptr, simply like
charptr = anothercharptr;
But this actually caused a compile failure in MSVC, saying charptr is being used without being initialized. in Code::Blocks it just gives buggy output.
I solved this issue by calling the function like
myfunct(&charptr);
and declaring the function like myfunct(char**);
and then I had to dereference the charptr in the function when assigning it to another ptr, so *charptr = anothercharptr;
It seems like you should be able to just pass a ptr into a function and change its address to that of another pointer? My main question is really, what is the value of a pointer? I thought the value of a pointer was just the memory address it contains. But then I had to reference it to pass it into the function.
What is the difference between the value of the char* charptr written as either charptr and &charptr?