Im starting with C. Like I said in the title, how do I assign the value from a function to a variable? I mean I have this function:
Code:
int EnteroAleatorio(){
rand();
return rand();
}
and I would like to assign the value of EnteroAleatorio to a variable in my main function, but when I try to do it and compile, I got the next error: non-lvalue in assignment
I've been experimenting with pointers and am getting the below error.
'error: cannot convert 'int**' to 'int*' in assignment'
I thought it was ok to assign a variable address to another variable. Line 18 is where I get the error.
I am trying to show the progression of memory as I increment it as I have done on line 17 and again, I don't know why I don't see a progression through memory locations when output to the console on line 20.
Here's the code:
#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;
int main() {
int *tt = new int;
int *p = new int;
[Code] .....
I have to ask system (linux) for a value and then assign it to the variable.
Example:
unsigned char date[] = system("date");
Of course this is wrong, but illustrated what is my goal.
How to achieve this effect ? I've heard about POSIX but how to include and use it.
I am writing a math program, using variables of type double, and had initialized all variables to 0.0.
I now realize that not all results will be valid.
Is there a way to explicitly assign a variable of type double a non-numeric value, for example, "NaN", "Undefined", or "Unassigned" or something like that?
That way, when I read through the printout of results, I will realize the "NaN" results indicate a valid solution was not found. Whereas a 0.0 might not stand out.
I'd hate to have to go back and delete the initialization, and then re-assign 998 values just for the sake of 2 non-solutions.
What I'm trying to do is to assign the length of a string to an integer variable. This is what i tried, it did not work.
Code:
printf("Enter a string
");
fgets(test_pass, 30, stdin);
strcpy(x,(strlen(test_pass)));
printf("%d", x);
This was just a test, and it did not compile. How to do this?
i want to assign number of bits by a variable in bitset? how to do that? like bitset<4> foo; instead of 4 i want to use some variable and later on by user i want to assign it! boost library or any other library!
View 1 Replies View Relatedwhat I need is to get the first integer from a file and assign it to a variable and the others integers to an array. Example: Thats my file content 5 4 6 7 8 0 and that would be the code:
Code:
struct Array{
int n;
int *v;
}
[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 RelatedI am developing a program that will read a function (x^2+2x+4 or other function) and then comparing and start assigning variables. My idea is with an array:
int i,x;
char xs;
char function[20];
cin.getline(function, 20);
cout << "Your function is: ";
[Code] .....
Well this is my basically idea, but when the program detect an ^ this will be associate with the exp(x,n); well in general the user enter a function: x^3+3x^2+4x-8 give a value for x for example 3 and the program will convert in -- exp(3,3)+3*exp(3,2)+4*3-8 --, but I don't know how.
I try to use passing function as argument but I'm stuck. I have two questions: First, I try to call uppercase and open .txt in tfm Second, How can I read characters from in.txt as string and assign to char content[] ?
#include <stdio.h>
void tfm( char str_filename[], void(*pf_convertion)( char content[]));
void uppercase(char content[]); //converts all letters to uppercase
int main(){
puts("-------------------------------");
printf("tfm:
");
tfm("in.txt", uppercase);
[Code] ....
I am a newbie to C++ and VS ++. I have created a windows form application by dragging and dropping button, label..etc. i wish label text to be appeared as return value from a function. The function returns ' const char* '.how this returned string pointer can be used to display label text.?
View 9 Replies View RelatedI want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like
struct item {
int ID;
int special; // for function
};
item Key;
Key.special = UseKey(KEY_KING);
// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this
if(iCurrRoom == ROOM_KING)
Key.special;
else if(iCurrRoom == ROOM_DRAGON)
Fireball.special;
I'm trying to figure out what is wrong with this:
static_cast<int>((pow(x, counter+1)) % 10)
it says "more than one instance of overloaded function "pow" matches the argument list"
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 trying to call a function through a variable
The error
|error: no match for 'operator=' (operand types are 'std::string {aka std::basic_string<char>}' and 'void')|
|warning: statement has no effect [-Wunused-value]|
||=== Build failed: 1 error(s), 1 warning(s) (0 minute(s), 0 second(s)) ===|
#include <iostream>
#include <fstream>
[Code].....
#include<iostream>
#include<stdlib.h>
using namespace std;
int Name(),Minimum(),Maximum();
int main() {
int name=Name(),minimum= Minimum(),maximum= Maximum();
[Code] ...
There are error to let user to key in minimum and maximum values, i would like to know whats the problem?
Expected output: 20
But what I got is: 22
Why. While calling sub function it should take the global variable am I right
insert Code:
#include <iostream>
using namespace std;
int a=0;
void sub()
[Code] ....
I get an error when i try to compile this code. I tried to allocate memory in main function and that works. But why it doesn't work in function? I think that there is something wrong with function argument, but not sure.
Code:
#include <iostream>
#include <fstream>
using namespace std;
struct Word
[Code].....
I'm currently writing a poker game and am trying my best to avoid using global variables. I have a few variables in int main() which i was hoping to use to store the value of each players hand. I then created a function which calculates the value of the hand but cannot get this value back into the main function.
For example:
Code:
#include <iostream>
using namespace std;
void getValue(int value) {
value = 4;
[Code] ....
Is there any way i can get the value of value using this function? If not what can I do?
This code is for a program that allows you to play a guessing game or arithmetic game and shows your total score from both as you go along. The program works fine the only problem I'm having is with the score. Is there a way to call the score value from the outside function into main?
Code:
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
//prototype functions
void menu();
[Code] .....
So trying to pass the value of score from the outer function int guessGame() into the score print statement in choice 3 of the main function? Oh and the "17 -turn_count" was just part of the requirements of the assignment.
I am trying to make a function that allows me to allocate memory to a "mem" variable and setting each of its chunk's status to FREE. FREE is defined as 0. Below is my code of the function.
Code:
int allocate(mem *mm, int num_chunks, int chunk_size) {
int i;
mem *temp;
if((mm = (mem *) malloc((num_chunks + 1) * chunk_size)) == NULL){
perror("Failed to Malloc
[code]...
mem; If my function works the way it should, it should print out five 0 because that is how I set them in the function, but this is not the case. I've looked at my function for 2 hours, but I could not figure out any logical error. Now, I think my problem lies with my limited knowledge of pointer arithmetic. On the other hand, when I insert 1000 as the second argument into my function, it gives seg faults, which is not the case for smaller values like 5, 10, 15, etc.
I was wondering if one could write a function that could accept one or the other variable type.
Ex: I have 2 arrays, int** and double**, and a function
Code: void PGMWrite(double** Matrix, int Matrix_dimension){.....}
Is there any way to change the function to
Code: void PGMWrite(int** Matrix || double** Matrix, int Matrix_dimension){.....}
And then have some sort of type identifier in the function that picks the correct section via an if loop? If so how, and how would I identify in the function if the input it type double or int?
I need to keep a static variable in a member function of a class that I have many objects of. I've had some trouble with it, and when I read up I found that such variables are static across all instances. Is there any way around this?
View 3 Replies View RelatedI want to get a random number from this function but idk if I did this function right....
int random(int x) {
srand(static_cast<unsigned int>(time(0)));
int randomN = rand();
x = (randomN % 10) + 1;
return x;
}
So, one can do stuff like this using #defines:
#include <iostream>
#include <array>
#define x arr[0]
#define y arr[1]
#define z arr[2]
class Point {
[code]....
... that is, to be able to reference the same data by "member variables" as by referencing a stl container. But defines are the devil's work - adding in a "#define x arr[0]" is a dangerous statement. I'd really like some nice clean C++ method (C++11 or C++14 are just fine) to do this without defines, but so far I'm drawing a blank. If arr wasn't an STL container, if we just wanted a pointer-based array, I could do it this way:
class Point
{
...
float x __attribute__ ((aligned (sizeof(float))));
float y __attribute__ ((aligned (sizeof(float))));
float z __attribute__ ((aligned (sizeof(float))));
float*const arr = &x;
};
... but you obviously can't do that if arr is an STL container.
The best I've come up with is to make x, y, and z function pointers, but then you can't call them like p.x, you have to call them like *p.x(), it's not very clean and I'd expect some added overhead. One could go even uglier and make x, y, and z be instances of some custom class with overridden operators that reference arr[], but that seems like it'd be just getting ridiculous in terms of overhead (both coding and performance)
In a project I am working on, I have to initialize a window and pass it as a parameter to another constructor, but before the window is initialized, it is passed as a parameter thus causing an error. Here is some code :
Game::Game()
: mWindow(sf::VideoMode(640, 480), "SFML Application", sf::Style::Close)
, mWorld(mWindow) //<---- right here is where the mWindow variable needs to be passed
{
//...
}
Is there a way to make this work???