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 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'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] .....
So I know that I can call a program by system("prog.exe"), but what do I add in when I want to pass a parameter?
View 2 Replies View Related I know there has to be a system call for a pause function. I simply want the program to pause for a few seconds before executing the next line of code. I do NOT want the user to enter a keypress, just pause the output or code execution for a few seconds.
system (pause); waits for keypress right? I just want it to wait 3 seconds before proceeding. I know it should take an argument for milliseconds right? Also, this is for a homework assignment I have already completed, just doll'in it up a bit for extra credit...maybe...
how to invoke a UNIX command within a program
I found this:
dd if=/dev/urandom of=myrandom bs=100 count=1
and I found this:
dd if=/dev/zero of=mytestfile.out bs=1 count=0 seek=1G
I want to call this command, by using the command line and typing Generate or something to that effect.
Basically, I want to be able to build random size files, content isn't important to me at this time.
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 know there has to be a system call to pause (not system("pause") execution of a program for a few seconds. I would like to give the illusion that my program is 'thinking' rather than just spit out the result as soon as the user has hit the enter key.
View 5 Replies View RelatedI 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.
I have written a program which uses a pid to check if the process is currently running and return a value based on the system call result.But the program core dumps
Code:
#include <stdio.h>
#include <string.h
int main( argc, argv )
int argc;
char * argv[];
{
int p_pid = 99;
char buff[1000];
}
[code]....
What is the mistake in this code and is it portable in both unix/linux , is the method secure (grepping for program name )?
I 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;
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]....
I am writing a program that minicks the library reserve system at my university and the problem is that when i run the code and reserve a room i am to keep track of the amount of times the room has been visited. To do this i set up a array roomcount and I count up by one every time i assign a room, The bug lies with when you reserve a room, then run option three, it will show that the previous visits is at 1, which is good. but then if i leave the room(option 2) and then run option 3 again to view the status of the rooms, the previous visits is set back to 0, which is not good. Ive been staring at this for hours and asked numerous people by we can't seem to figure out why the roomcount variable resets.
#include <stdio.h>
#include <math.h>
int main (void) {
int choice;
int roomchoice;
int i = 0;
[Code] .....
Im building a banking system. in my create_account it asks for account address and phone number as well as other questions. When I go to my Show account info (balance inquiry) I notice its not getting the right address as well as phone number. its showing "garbage".
Code:
/********************************************************************
* Vincent Dotts 09/29/2014 ch11.cpp *
* This program serves as a customer banking system *
*****************************HISTORY*********************************
* WHO DATE Discription *
*********************************************************************
* VD 09/30/2013 Created program *
********************************************************************/
#include<iostream>
#include<fstream>
[Code] .....
I am trying to generate a couple of vectors, but the exact number of vectors that will be needed can only be determined at runtime. Therefore I had the idea to use a macro call and text substitution in order to declare the necessary number of vectors. Unfortunately, the arguments of a macro call are always (as far as I know) considered text only. So, the loop in my example below in which I am trying to generate the following code:
vector<int> vector0;
vector<int> vector1;
vector<int> vector2;
vector<int> vector3;
does not work.
#include <iostream>
#include <vector>
using namespace std;
#define declareVec(vecno) vector<int> vector##vecno;
[Code]......
I get an an error message 'vector0' was not declared in this scope.
I also tried to initialize a string or char with the content "0" and then pass this string or char to the macro call, but this did not work either.
Is there any way in which I could use the content of an integer variable or any other variable as arguments for a macro call?
What is Function call Overhead and Function Call Stack?
View 2 Replies View RelatedThis is my code , i should Assign value val to interval [keyBegin, keyEnd).
#include <assert.h>
#include <map>
#include <limits>
void assign( K const& keyBegin, K const& keyEnd, const V& val ) {
if(!(keyBegin<keyEnd))
[Code] .....
I have array of pointers and when i tried to assign values dynamically all array items have the same value which is last value.
char* list[];
int DynamicDemo(void)
{
[Code].....
I am having some difficulties knowing how to assign city to the list.
Code:
class DestinationList
{
private:
int num;
// number of objects in the list
Destination list[MAX_CITIES];
// array of destinations
public:
[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 RelatedWhy would you ever assign a pointer to an existing array?Take this link for example. URL....I understand that pointers use dynamic memory allocation so they are much more flexible then a built in array, but if you already have an existing array, don't you already have static memory allocation for that array? Why bother assigning a pointer? Regardless of the pointer, doesn't the program still allocate static memory to the array anyway?
View 3 Replies View RelatedI have a silverlight app that uses TextBox XAML controls.
In the c++ code-behind, IXRTextBoxPtr types are associated with these textboxes using "FindName" like this:
FindName(L"ColNum3", &m_pColNum3);
(where ColNum3 corresponds with the XAML CODE like this: )
Then, the code assigns the pointer like this:
std::wstring wsTransfer; // gets the wstring from imput
const WCHAR * wpszInput;
wpszInput = wsTransfer.c_str();
m_pColNum3->SetText(wpszInput);
but the display does not show the text data.
What am I missing? What steps am I missing to have this text modification display on the screen?
Below assignation? It is a bit confusing.
myString = ""myInteger"is";
I am making a game Pong, and have been struggling with the collision aspect between the baal hitting off the paddle. I have created a Class, to draw a rectangle, to work with collision however I dont know how to assign the rectangle to the images of the ball and paddle.
#include "stdafx.h"
#include <iostream>
#include <time.h>
#include <vector>
#include <cmath>
#include "gwin.h"
const int NUMBEROFBALLS = 1;
[Code] .....
