C++ :: Forceful Type Cast Not Working
Mar 6, 2015
I am writing a program with FLTK and in event handling part wanted to send the address of the handler function to callback function. Type cast just does not work.
Code: btnOpenDB->callback(&FLUI::WndMain::DBOpenBtnClick_scb, reinterpret_cast<void*>(&WndMain::DBOpenBtnClick_cb));
I want to cast "a pointer to a class member function which accepts one argument" to a void pointer. After all it is just an address. So it is logically possible to cast it. Isn't it? Actually an static_cast should be enough!
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May 7, 2014
I have this program.
Code:
int test_variable;
int main() {
test_variable = (int)0x12;
}
Now my doubt is what is the advantage of type casting 0x12 to int. suppose if the test_variable data type is "char" then should i type cast to "char"?
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Aug 1, 2012
my array contains elements of integer type
how can i convert my array to long array
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Oct 22, 2013
I've created a function where you can choose any bounds for an array based list (positive or negative, as long as the first position is smaller than the last position). However for some reason when I call the print() function in my application program it doesn't do anything. My print function is technically correct (I still have work to do on the output) but I can't figure out why it wont show anything at all. Below is my header, implementation, and main program files, along with results from running the program.
Header File:
//safearrayType Header File
class safeArrayType {
public:
void print() const;
void insertAt(int location, const int& insertItem);
safeArrayType(int firstPlace=0, int maxPlace = 100);
[Code] ....
ResultsEnter the first bound of yourlist: -3(this was my input)
Enter the last bound of yourlist: 7(this was my input)
Press any key to continue...
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Oct 2, 2014
Is it possible to get the string representation of an int. So I mean if i have: 5, I want to get '5'.
I was searching in the internet and I found this solution:
Code:
int number = 5;
char c = number + '0'; which works fine for small numbers, but if I do:
Code: int i;
char c;
for(i =0; i < 10000; i++) {
c = i + '0';
printf("%c
", c);
}
At some point some strange sings like %&/)/)$%&) are appearing, But i really need this huge numbers as well .. Is there any other way to do this??
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Sep 29, 2013
How to cast an int to a string I came across this code:
#include <iostream>
#include <string>
int main(){
double f = 23.43;
std::string f_str = std::to_string(f);
std::cout << f_str << '
';
}
Unfortunately, using Dev C++ Version 5.4.2, I'm getting an error:
[Error] 'to_string is not a member of 'std'
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Dec 7, 2013
In my refference book I have got a example with a part saying to access the a[4][0] element of the array (named a) with pointer this can be written:
*((int*)a+4)
I wonder if the cast is really required. The book says it is required so that the pointer arithmetic can be done properly. However I am not sure about it. When I work with pointers defined by myself I don't use casts similar to this one. Is there a difference between a self defined pointer and array name?
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Mar 14, 2012
Code:
namespace ConsoleApplication1 {
class ImplicitlyConvertibleFromFoo {
public ImplicitlyConvertibleFromFoo(Foo foo) {
this.foo = foo;
}
Foo foo;
[code]....
Any way to easily convert arrays of user-defined types?
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Jun 20, 2013
Here is the code,
Code:
class B {
};
class D1:public B {
};
class D2:public D1 {
};
int main() {
B& b = dynamic_cast<B&>(*(new D2));
return 0;
}
D2 is actually grandchild of B, so D2 object reference can still be converted to B reference without any exception. Is it legal?
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Mar 18, 2013
The warning: :63:7: warning: passing argument 1 of fputc makes integer from pointer without a cast [enabled by default]
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/stat.h>
[Code]....
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Dec 15, 2013
Code:
#include <stdio.h>
#include <stdlib.h>
#define CLASS 4
#define STUDENT 11
#define GRADE 5
[Code] ....
Giving me that error on 75:10
avesub+=grade[k];
and 90:17
donkeypunch+=grade[j][k];
not sure exactly why
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Apr 18, 2014
I cannot get the following to compile. The problem is the printf on the last line. I understand that printf requires a char (or pointer to char). I understand that I can convert between datatypes by putting the target data type in parenthises in front of the variable. But how do I cast the integer into a character and then get it's pointer to pass into printf?
Following is my code. I compile with gcc temp.c -o temp.
Note that I have tried many attempts at that last line and this is just the one that I really, really think should work (or is at least the closest to the correct answer).
This code shown below, using printf("%s", &(char)nextChar); returns
temp.c:26: error: lvalue required as unary '&' operand
If I try to use printf("%s", *(char)nextChar); I get the error
temp.c:26: error: invalid type argument of 'unary *' (have 'int')
This line printf("%s", (char)nextChar); returns the obvious
format '%s' expects type 'char *', but argument 2 has type 'int'
Code:
#include <stdio.h>
int main() {
printf("hello, world
");
#if defined(SUNDIALS_EXTENDED_PRECISION)
[Code] ....
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Oct 10, 2014
Is it possible to handle situations where static cast fails. I have a sample code written belo:
typedef struct test {
int a;
int b;
} tester;
void setevent(void *in) {
tester *recv = static_cast<tester*>(in);
[Code] ....
In above code when setevent is called with the tester object, there is no issue, but if we pass random value it leads to seg fault. This is because static_cast is not type_safe, but can it be handled in any other way?
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Oct 10, 2013
Is there a difference between having static and dynamic cast in this scenario? The output is the same.
Code:
Base* pb = new Derived();
if(Derived* pd2 = static_cast<Derived*>(pb)) // true {
pd2->get_price(); // calls Base::get_price()
pd2->get_rate(); // calls Derived::get_rate()
[Code] ....
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Apr 10, 2015
I have a library function with a prototype:
Code:
void func(unsigned char* in);
I would like to pass a std::string to it, so I tried:
Code:
std::string temp = "Hello!";
func((unsigned char*)temp.c_str());
This works, but I thought it was good practice for type safety to use C++ style casting, yet reinterpret_cast does not work in this instance as it fails:
ERROR: reinterpret_cast can not cast away const or other type qualifiers
and const_cast fails with:
ERROR: a const_cast can only adjust type qualifiers, it cannot change the underlying type
So what is the correct method of casting here assuming I can not change the library interface, and my data is kept in an std::string?
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Jul 1, 2013
I've got two classes, which are both derived from the same two base classes. Here's a representation of the actual code:
Code: #include <vector>
class BaseClassA {
};
class BaseClassB {
};
class TestClassX
: public BaseClassA,
public BaseClassB
[code].....
Basically, I'd like to know if it is possible to cast directly from a BaseClassA pointer to a BaseClassB pointer, without casting to the child class first.
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Jan 23, 2014
int hash = 0;
char *strings[100];
if((int)strings[i] != 0)
if((int) strings[hash] != 0)
while((int) strings[hash] != 0)
if((int)strings[hash] != 0)
if((int)strings[hash] != 0)
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Oct 24, 2014
I programming currently something with OpenGL. Now I have written some wrapper classes, like Shader, Program .... All works fine, but I don't like to call Shader.GetHandle() every time I want to call a OpenGL function manually where I need the object handle/id. (GetHandle() returns the OpenGL ID of the object)
So now I wonder, is it possible to program it in C++ so, that I can put my objects to gl methods and c++ automatically pass the handle/id member to that function ? Is there maybe a operator that I can use for that?
For example:
The way I do it now:
Shader vertexShader();
glCompileShader(vertexShader.GetHandle());
The way I want to:
Shader vertexShader;
glCompileShader(vertexShader);
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Mar 6, 2015
Code:
#include<stdio.h>
print_int_ptr(int *a){
printf(" a %i
" ,a);
printf(" &a %i
" ,&a);
[Code] .....
I get that warning : passing arg 1 of `print_int_ptr' makes pointer from integer without a cast|
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Jan 18, 2015
Code:
#include <stdio.h>
int main(){
int a=15 ;
int b =20 ;
strcmp((a, "20") == 0) {
printf("Correct!");
[Code] .....
passing arg 1 of `strcmp' makes pointer from integer without a cast
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Mar 26, 2014
I am having some errors with pointers and passing arguments.
Code:
#include <stdlib.h>
#include <stdio.h>
#define MAX_FILE_LENGTH 20
typedef struct node_{
int value;
struct node_* next;
[Code]....
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Sep 21, 2013
I have a function that I want to exit gracefully when an "error" occurs in an input file. My function declaration is:
Code: BSTnode *buildTree(FILE *fp)
The few lines that are causing the problems are:
Code: if(regcomp(®ex, to_find, REG_EXTENDED | REG_NEWLINE) != 0) {
fprintf(stderr, "Failed to compile regex '%s'
", to_find);
return EXIT_FAILURE;
}
I know that if I just use "return" by itself the warning goes away but fails to exit when the error occurs. I also believe this may not be the correct use of stderr. But I need the program to exit when an error has occurred.
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Apr 25, 2013
I having a problem which I'm not able to resovle. I try to dereference a void pointer but I always get a C2440 error. It says: 'static_cast':void* cannot be converted in wqueue<T>. I tried different cast ways but I always get the same error. As far as I found out I should get the error if I try to dereference without cast but in my case I cast before and still get that error.
void *srumbler (void *arg) {
wqueue<workclas*> m_queue= static_cast<wqueue<workclass*>>(arg);
return NULL;
}
The according type wqueue in the header file:
template <typename T> class wqueue {
list<T> m_queue;
pthread_mutex_t m_mutex;
pthread_cond_t m_condv;
[Code] .....
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Feb 26, 2013
I have the next program: if I comment the assignation mNum=num; or mCh=ch the segmentation fault don't exist.
#include <vector>
class Base{
public:
[Code]....
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Jul 4, 2013
The log file gives me: In function ‘memFileAlloc’ assignment makes pointer from integer without a cast..When compiling the drivers for the Matrox card in the DL580. The offending code is:
STACK_LINKAGE MEMHANDLE memFileAlloc(
UINT32 dwSize,
const char* pszFileName,
int iLine) {
void* pvChunk;
#if MEMORY_STATS
[code]...
I think the offending line is:
pvChunk = ClientMemAlloc(dwSize + sizeof(UINT32), NULL)
because that's what the log file tells me.
The system is a 16 core HP DL580 G4 with 8g RAM, RAID 0, Mandrivalinux 11.0 and the display is a Matrox Parhelia 256PCIx.
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Dec 17, 2014
Following is my xml file called PropertyInfo.xml :-
<?xml version="1.0" encoding="utf-8" ?>
<PropertyInformation>
<locations>
<location name="Bombay">
[Code].....
In above LoadPropertyInfo() method, how to cast DataSet to List<Location> locations before returning "locations" ?
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