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?
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.
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
If i declare 2 variables like this static int first, second; will both of them be declared static or will only first be declared static and second a regular variable?
#include<iostream> #include<conio.h> #include<string> using namespace std; class ir; class Bank_acc { private: string name,type,s; long int accno,temp,balance,in;
[Code]....
errors are:
|6|error: forward declaration of 'class ir'| |54|error: invalid use of incomplete type 'class ir'| |99|error: no matching function for call to 'ir::interest()'|
T minus 10 and counting T minus 9 and counting T minus 8 and counting T minus 7 and counting T minus 6 and counting T minus 5 and counting T minus 4 and counting T minus 3 and counting T minus 2 and counting T minus 1 and counting
Declare the following index before the while loop:
int index = 10;
Correctly code a while statement below using the variable index as defined above, to produce the output shown above.
So this is what my code looks like... I also have to convert this same loop into a do while and for loop. So if I can get this one right I think the others should come relatively easy.
while (int index >= 10) { cout << "T minus " << index; index--; }
im doing a program to store name, age, time and fitness. and i need to hold a table of 5 such records.can i do this?
#include <iostream> using namespace std; int name1, age1, time1, fitness1; int name2, age2, time2, fitness2; int name3, age3, time3, fitness3; int name4, age4, time4, fitness4; int name5, age5, time5, fitness5;
I wrote the following program to initialize a string after the variables is declared, but it isn't working. A warning is given by the compiler, and the execution of the program shows a strange string. How do I initialize variable word in a separate statement from its declaration?
I'm having to do a little c++ (coming from java) and don't understand the syntax of the following declaration
Code: SensorBase* const sensor(mSensors[i]);
It looks like it's declaring a const pointer to a SensorBase object but I don't understand how that applies to sensor(mSensors[i]) which looks like a function??
I am getting a compilation error from the code below. It is when i am naming a variable with my user defined type.
#include<iostream> #include<cstring> #include<cstdlib> using namespace std; class person {
[Code] .....
C:Dev-CppTRIAL.PASS.!!!.cpp In function `int main()': 66 C:Dev-CppTRIAL.PASS.!!!.cpp expected primary-expression before "p" 66 C:Dev-CppTRIAL.PASS.!!!.cpp expected `;' before "p" 74 C:Dev-CppTRIAL.PASS.!!!.cpp `p' undeclared (first use this function) (Each undeclared identifier is reported only once for each function it appears in.) 83 C:Dev-CppTRIAL.PASS.!!!.cpp `X' undeclared (first use this function)
I have an issue converting VC++6 code to VC++ 2010. The following template function definition is not allowed by the new compiler:
template <> void AFXAPI DelElems <CBrush*> ( CPen** objects, int count ) { for ( int i = 0; i < count; i++, objects++ ) if (*objects) delete *objects; }
All errors refer to the header of the template function:
- syntax error : '<' - syntax error : missing ';' before '<' - 'DelElems' : illegal use of type 'void' - unrecognizable template declaration/definition
I found way around this, but I would like to know why it shows multiple declarations.
My solution is to declare this class in function body(void LoadLevel()), just before the throw statement. But why can't I define it inside my namespace, but outside function?
how to get this bug to go away and I am stressing about it. The project im working on simulates packet sending and receiving along with ROT13 encryption of the packets. The error lies within the .cpp file anywhere that I used IPHost.
header file
#ifndef IPHOST_H #define IPHOST_H #include <string> #include <iostream> class IPHost { public: //Default constructor defaults to 0.0.0.0
[code]...
error message:
In function 'ZStorSt13_Ios_OpenmodeS_': line 11: multiple definition of 'IPHost::IPHost()' line 11: first defined here
**this error repeats for every line in the .cpp in which IPHost is used.
What is the best way to define const strings when there are separate header and source files?
For example, I have a header that only declare some enums. In that same header I would like to add string representations of those enums so that I can print them easily i.e string_representation[my_enum] for debug and error printing and so on.
If I define them in the header file, I will get a linker error for multiple definitions. If I remove the definition, then I can not define it in the source file.
I have observed that inline functions can not be prototyped. example:
.cpp file:
inline void whatever() { cout<< "this is inline"<< endl; }
.h file, prototype inline void whatever(); //would ask for a definition
Because of this, I have have just made functions that are used in only 1 .cpp file (ever) inlined, to make it more efficient (and it has demonstrated that it is more efficient). It's worked out fine so far, but what about the scope of the definition??
Since an inline function is like a templated function, in that it can't be prototyped, how are name conflicts resolved, and what is the best practice for writing inline functions??
Example of a conflict:
//in some arbitrary header... void do_somthing(); //in .cpp file that inlcudes the header... inline void do_somthing() { cout<< "I'm doing somthing!!"<< endl; } int main() { do_somthing(); //which one?? it compiles fine though!! return 0; }
vijay13@ubuntu:~/Downloads$ g++ -o test test.cpp -I /home/vijay13/Downloads/OGDF-snapshot/include/
I am getting following error:
vijay13@ubuntu:~/Downloads$ g++ -o test test.cpp -I /home/vijay13/Downloads/OGDF-snapshot/include/ /tmp/ccPE8nCu.o: In function `main': test.cpp:(.text+0x26): undefined reference to `ogdf::Graph::Graph()' ...................... so on
I changed the name of my Invoice class to 'Application' and then it generated errors such as follows
Error9'Invoice.Invoice' does not contain a definition for 'Documents' and no extension method 'Documents' accepting a first argument of type 'Invoice.Invoice' could be found (are you missing a using directive or an assembly reference?)c:userskeildocumentsvisual studio 2013projectsinvoiceinvoicewritefile.cs1840Invoice
Error3'Invoice.Invoice' does not contain a definition for 'Run'C:UsersKeilDocumentsVisual Studio 2013ProjectsInvoiceInvoiceProgram.cs1921Invoice
I have added my classes here, lso I have added the sln to this post.
using System; using System.Collections.Generic; using System.ComponentModel;
I'm working on a personal project, where I have a database (SQLite) and a dataGridView. Now This is what I have:
public Form1() { DataSet ds = new DataSet(); SqlConnection connection = new SqlConnection(@"Data Source=testingsql2.s3db"); SqlDataAdapter SQLda = new SqlDataAdapter("Select * from User", connection); SqlCommandBuilder SQLcb = new SqlCommandBuilder(SQLda); dataGridView1.Fill(ds, "User"); //Error here dataGridView1.DataSource = ds; dataGridView1.DataMember = "User"; }
I've marked where I get the error.
And the Error description: Error 1 'System.Windows.Forms.DataGridView' does not contain a definition for 'Fill' and no extension method 'Fill' accepting a first argument of type 'System.Windows.Forms.DataGridView' could be found (are you missing a using directive or an assembly reference?)
I am unable to understand how a move constructor works in this example of code. If someone could break down the process of what is taking place and explain to me on why to use a move constructor.
Code: class MyString { MyString(MyString&& MoveSource) { if( MoveSource.Buffer != NULL ) { Buffer = MoveSource.Buffer; // take ownership i.e. 'move' MoveSource.Buffer = NULL; // set the move source to NULL i.e. free it } } };
Example from "SamsTeachYourself: C++ in One Hour a Day"
