I have just learned about how one can put functions and headers in different files from the main() function. I was wondering if there is a rule of thumb of when and when not to separate the two, or if it's merely preference. Is there perhaps an "industry standard" regarding this, for those who program in C for a living?
View 4 RepliesSo I have a rather large (for me) project, requiring me to have two .cpp files and a header. Anyway, both of the .cpp files #include the header file, but I recieve linker errors because the variables and functions in the header are declared and defined twice (once in each .cpp file). How am I supposed to do this?
View 8 Replies View RelatedI have a question regarding how GCC relates a header file and its binary file.
main.c
#include <math.h>
#include <stdio.h>
int main (void){
double x = sqrt (2.0);
printf ("The square root of 2.0 is %f
", x);
return 0;
}
we can compile it by running the line: gcc main.c -lm -o main
My question is: How GCC knows where is the definition of sqrt?
First I was thinking that there was and object file with the name math.o inside libm.a (that is GCC will look for an object file with the same name as the header file), but after running the next line I think my assumption was wrong as there is not such file in libm.a.
nm libm.a | grep math.o
nm: e_acos.o: no symbols
nm: k_cos.o: no symbols
nm: k_sin.o: no symbols
[Code] ....
Code:
struct magic {
char windowsheader[2];
} magicnumbers;
struct bmp {
unsigned int sizeofthefile;
short int applicationspecific1;
[Code] .....
When I run this program, seems like it is working,at least I am sure that it gives the right file size. But if I don't use struct magic and instead use:
Code:
struct bmp {
char windowsheader[2];
unsigned int sizeofthefile;
short int applicationspecific1;
short int applicationspecific2;
//same lines with above
} bitmap_header;
And if I don't use first fread:
Code:
fread(&magicnumbers,sizeof(magicnumbers),1,fp);
Then the values which structure "bmp"'s variables get become wrong. Of course I change the related printf to:
Code:
printf("
windowsheader:%d %d
",bitmap_header.windowsheader[0],bitmap_header.windowsheader[1]);
Why does the problem happen,what is the difference between them?Why do I have to use separate structs?
Assume a class named Dollars exists. Write the headers for member functions that overload the prefix and postfix ++ operators for that class.
View 1 Replies View RelatedI am trying to use a combination of windows batch scripts as well a C++ program to put users data into one single .CSV file. Right now, I have a batch file that will output data from the command line into multiple .txt files. These files are mac.txt, serialnumber.txt, computermodel.txt, and computer name.txt. What I want to do, is to have users run the batch file, which will in turn run the .exe C++ file which will concatenate all their data into one file, computerinfo.csv. The file format for this file would be to have the mac address, serialnumber, computer model, and computer name all in their own column.
My main issue is that these individual files don't have the format that I would like, but based on the command prompt functions, there isn't really any good format. For example, the mac.txt file has the following format:
Physical Address Transport Name
=================== ==========================================================
xx-xx-xx-xx-xx-xx DeviceTcpip_{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
yy-yy-yy-yy-yy-yy Media disconnected
zz-zz-zz-zz-zz-zz Media disconnected
but all I really want is xx-xx-xx-xx-xx-xx
The other files have other issues with format, but if I can figure out this one then the others should be a piece of cake.
Also, I want the output of this to all go in one row, and as other users run this file, they will go into new rows without touching the rows above.
I could do the assignment if all i had to do was create a function within one file, call it in the main class, and that would be done with it. no, my teacher wants us to have our main program, a header and a separate class file and create functions in it in which we can then use in the main file.
This is the main file:
#include <iostream>
#include "call.h"
using namespace std;
int main() {
int length; //holds the length of the call in minutes
int hour; //holds the hour od the day(0-23 military time)
[Code] .....
I have a big big problem with class template
//file Array.h
#ifndef ARRAY_H_
#define ARRAY_H_
template <class T> class Array {
[Code] .....
I've tried many ways:
1. put #include<Array.cpp> at the end of file Array.h
2. Change Array.cpp to Array.hpp,...
But dont work at all
I have tried to separate class template into two files.
So I have 2 seperate base classes, (note that I removed the variables and functions that do not relate to the topic) Object.h
class Object{
public:
Object();
~Object();
[Code].....
The error I get is saying I am calling a function declared with one calling convention with a function pointer declared with a different calling convention and this makes perfect sense because for some reason, the function pointer is pointed at the virtual function Object::update but I can't figure out why and how to make it point at the virtual function Drawable::getImage.
Also, the virtual update function is called in a different place just before this and works correctly.
I am struggling to enable friendship between two classes in separate header files for a banking program.
I am attempting to get the Person class to use variables from the Account class. Heres what I have so far.
ACCOUNT.h:
Code:
#include<iostream>
#include<fstream>
#include<cctype>
#include<iomanip>
#include <string>
#include <math.h>
#include <windows.h>
#include <vector>
#include "Person.h"
using namespace std;
class person;
[code].....
My question portion is attached. The code I have written is below.
#define _USE_MATH_DEFINES // for C++
#include <cmath>
#include <iostream>
#include <iomanip>
[Code].....
I currently have a running program "game.cpp" that runs a game of tic tack toe. I want to split the working functions into header files so that game.cpp isn't so cluttered. I have created two header files "displayBoard.h" and "gamePlay.h" but they wont compile because the functions are looking for variables that haven't been declared. First, here's the working code.
#include "displayBoard.h"
#include <iostream>
#include <limits> //This is required to catch invalid user input
class ticTacToe //A class to contain all our functions {
[Code] .....
I'm working on a code that reads a text file and follows the instructions written in that file. An example of the text file:
*sum
11 4 61 2
1 2 0 14
17 99 1 1
*subtract
5 6 7
1 1 1
45 6 9
I want to read the text file line by line, each time I find an instruction (that is, the keywords *sum or *subtract) I want to make a summation (in the case of *sum) of all the numbers in each of the following lines, and repeat until the next instruction appear. So the text file above should generate:
78
17
118
-8
-1
30
That is:
11 + 4 + 61 + 2 = 78
1 + 2 + 0 + 14 = 17
17 + 99 + 1 + 1 = 118
5 - 6 - 7 = -8
1 - 1 - 1 = -1
45 - 6 - 9 = 30
how can I implement a dictionary(I'm guessing a dictionary is the best way to go here) so that when I read the string *sum i can call a function that does the summation of the following lines.
the size of the text file may be big (several mb) and the number of different instructions to search for may be in the magnitude of hundreds.
In general, my problem is that I've been trying to reorganize the project I and my group are working on into separate project files. Everything was working perfectly fine before, but now I'm facing the wrath of undefined reference errors when I try to call my DLL functions.
I have them declared and included in the central header file here :
Code:
/* DLL functions */
typedef void ( * t_wait )( int milliseconds, const int frames_per_seconds );
typedef clock_t ( * ft_timer )( int command, t_timer * timer_object ); /* clock_t is usually defined as long */
typedef void ( * t_SDL_errorexit )( const char * message );
typedef SDL_Surface * ( * t_load_image )( char * image_path, unsigned is_transparent );
[Code]...
Then I have them imported here :
Code:
/* ******************************************************** */
/* ********* win_error( char *, bool ) ********* */
/* ******************************************************** */
/* - Displays a GUI for a windows specific error message, */
/* pass true to it to have it exit the program, pass false */
/* to have it continue */
/* ******************************************************** */
extern void win_error( char * message, bool is_exit )
{
/* Note : win_error uses the Win32 Api */
/* ********************************** */
char buffer[BUFSIZ] = { 0 }; /*
[code]...
This doesn't work, as my compiler sees it that I am trying to call invalid functions, whereas I have made sure to import the functions before calling. Obviously my compiler can't tell that, and is trying to protect me from calling them.
The source files are compiled as C++, but I'm using C-style code instead of true C++ code.
Obviously I'm using Windows style DLL linking, but if the only ways to share imported functions are non-standard, only post ways that will work on as low as Windows XP.
I have tried to statically link them before, but that led to a problem that I posted a while back. Which led me to dynamically linking, which was problem-free until I separated my code into separate files.
I'm trying to print a single linked list backward with functions/classes. I have created the main file and 3 header files. But I'm getting an error on one of the header files, linkedListIterator after adding #include "linkedListType.h". It says that "linkedLlistType.h" is calling itself. And when I try to run it, I get an error of "too many header files." I have tried changing the headers many times, but nothing seems to work.
.cpp file:
/*(Printing a single linked list backward) Include the functions reversePrint and recursiveReversePrint, as discussed in this chapter, in the class linkedListType. Also, write a program function to print a (single) linked list backward. (Use either the class unorderedLinkedList or the class orderedLinkedList to test your function.)*/
#include "linkedListType.h"
#include "orderedLinkedList.h"
#include "linkedListIterator.h"
#include <iostream>
using namespace std;
struct nodeType
[Code] ....
header files:
[URL] .... (error in this header file)
[URL] ....
I am currently working on data abstraction. I was able to write a class (a simple clock, see Malik's C++ book, Chapter 12 for reference). As you can imagine, I am quite new to programming and C++.
Well, now I created a header file clock.h that includes the class definition and function prototypes as well as a implementation.cpp file with the implementation details of the class.
I managed to include all this in my program.cpp and compile it (using dev c++). Everything works exactly as I want it to.
So now my question is, how can I create ... I am not sure how it is called ... a header, but without revealing to the user how the functions are implemented. Basically the user should get a file (the object code of the header + implementation.cpp?) and simply #include it into his own program.
So instead of giving the original header + implementation.cpp to the user I want to hide how my class does its stuff and instead just provide some file that can be included and then used in a program (I will write a documentation how to use the class).
I am not sure how all this is called, I am sure there is some name for it...
I want to read/write the excel sheet using C++. how to add the excel library or include the headers ?
Inot possible than is there any other way to work on Excel using C++.
I am testing HTTP Headers and I have an strange problem. When I get the response of the server, it is the correct one the first time. If I use a for loop to send more than one request and get more than one response, this response seems to be overlapped with the previous ones. To a better explanation of the problem I attach the code I am using and the output generated:
TCPSocket.h
-----------
#ifndef _TCPSOCKET_H_
#define _TCPSOCKET_H_
class TCPSocket {
private:
int localSocket;
[Code] .....
So, a bigger loop, a bigger the response of the server. However, I know the response of the server is always the same.
I want to include boost directory. What must be in the Additional Include Directories input?
I tried
C:C++boost_1_55_0libsaccumulatorsexample;$(BOOST_ROOT);%(AdditionalIncludeDirectories)
But I am still getting error "Cannot open include file: 'boost/libs/accumulators/lambda/lambda.hpp': No such file or directory" when I include
Code:
#include <boost/libs/accumulators/lambda/lambda.hpp>
The file is placed out side of boost directory of sure.
On my program I use a counter to count to 10, then i ask for a string, in this case "yes" or "no", during the count, i want to keep the user from putting inputs in, due to the fact that if they put both "yes" and "no" before the program reads the string.
Code:
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <stdbool.h>
#include <time.h>
#include <string.h>
}
[code]....
I 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;
}
# include <stdio.h>;
int main (void){
float judges[6];
int degree;
[Code].....
So I have a double array, where I'm inputting float numbers to certain points in an array. Sometimes, the numbers that are printed out are completely different from what I put in.Here is the part of the code:
Code: .
while( token != NULL ) {
num = atof(token);
test[j][i] = num;
printf( "
%s, i is %d, j is %d
", token,i,j );
printf( "number is %f
value test of i,j is %f
[code]....
Why the float num prints out fine, but when put into an array becomes garbage?I'm taking string values from a csv file and turning them into floats, but no problems seem to crop up there.I reset i when appropriate and increment j when needed, so I don't think my problems are from incorrect array values (though they might be)
I'm having a little problem where after reading a file I'm unable to update my struct with some particular info. It is actually a linkedlist. This is my struct:
Code:
struct node{
int id;
char name[50];
struct node *next;
}*head;
And in my Main function:
Code:
int main(){
int i, t_id, num;
struct node *temp;
char name[50], t_name[50], input_name[50], line[LINESIZE], *value;
struct node *head = NULL;
FILE * ifp = fopen("AssignmentOneInput.txt", "r");
[Code] .....
Basically in the while loop when I input something like this for updating numbers:
Code: temp->id = num; //These are numbers separated by a comma. or this:
Code: strcpy(temp->name,value); //These are names The program crashes
The first line of my input file is going to contain some number "T" which will represent the "combination length" of a list of random words. (In this case, they are Taco Bell items). The first number on the second line represents the number of unique items on the menu to get, and the second number on the second line represents the number of unique items that are supposed to be bought.
Basically the input will look like this: 2 3 2 taco burrito nacho
And the output looks like this: burritos nachos nacho taco burrito taco
This is what I have so far:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
int main(void){
int N, T, K;
char menu[N][20];
[Code] .....
What I am trying to get working right now is just to scan a file and put the strings into an array so then I can work on sorting the array. How can I add strings from a file into an array?
I am at a loss with an assignment. I am supposed to read from a text file, with an input of something like this: alphaproleone,stroke,42 1 and Store it into an array of structures and then output it with each word/number starting on a new line. My current code prints out only the first part, and the "a" in alphaproleone is the actual number "21".
#include <iostream>
#include <string>
#include<fstream>
#include<iomanip>
using namespace std;
typedef struct drugtype {
string name, target;
int effectiveness, toxicity;
[Code]...