C++ :: Segfault At Declaration Of 2D Array
Jan 19, 2014
I have a little program that does some statistical processing on text files. The program has thrown a segmentation fault with an input file that is larger that I have used before. I didn't write this tool, so I went searching for the problem. Data from the input file is dumped into a 2D array and the program fails at the declaration of that array.
Code : double A[cont][Nr_col_split];
The vales for cont and Nr_col_split and determined from the input file and in this case, cont=807 and Nr_col_split=350. I assume that these values are just too large and not enough memory can be allocated, or something like that. Do I need to use reserve or similar to set aside enough memory? I will have input files that are quite a bit bigger than this one, so perhaps there needs to be a different solution for storing the input file data.
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Nov 2, 2013
I wrote a program to detect if a graph is tree or not. Initially it was using static memory. Later I changed it to use memory dynamically using malloc().My problem is that, my program it works great for case when graph is not tree but fails if it is.
Code:
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
int main()
}
[code]....
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May 22, 2013
I am trying to send a packet across a client/server communication. I am getting a seg fault (while running the program(It compiles fine)) when I try to read the neighbor file, You should be able to see this below the comment /***** Read neighbor file***/ :
Code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
}
[code]....
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Mar 18, 2014
The program I'm working on is a very basic relational database. I've isolated my problem for simplicity. I get a segfault right here when I try to access db->relationCount. I tried printing db->relationCount from within loadDB and that worked,
[code]
loadDB(db, configFile);
printf("%d",db->relationCount);
fflush(stdout);
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Jan 7, 2013
I would like to know the difference between the following two forms of array declaration:
(1)double myArray[3] = {1.0, 2.0, 3.0};
(2)array<double,3> myArray = {1.0, 2.0, 3.0};
If I say the second one allows to use different functions like .begin(), am I right? Is there any other difference between these two declaration?
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Jan 24, 2014
I want to understand the ways in which arrays can be declared and used. What each of the following do or what's the difference between them and what would be the length of each:-
1 - char ary1[50];
2 - char ary2[50] = {'H','e','l','l','o'};
3 - char ary3[50] = {'H','e','l','l','o',' '};
4 - char ary4[50] = {' '};
5 - char ary5[50] = {' ','H','e','l','l','o'};
6 - char ary6[50] = {' ','H','e','l','l','o',' '};
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Jan 6, 2013
I'm currently programming a server which uses multiple threads- I have a class for one map in the game. Each map has a thread for timed events(tile regeneration, NPC regeneration, etc.), and a thread for handling NPCs(movement, combat, etc.). A basic structure of the class looks like this:
class Region {
public:
/* game values are here, they are public so
they can be accessed from outside of the class
inside of packet-handling functions and such */
int value;
void *Function();
[Code] ....
The program crashes when I use a member of the same class the function is located in- in the context I have shown about it would crash on "value++".
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May 5, 2014
I was going through a code where i found the definition of int array[63] in one of the source files. But i also found the declaration as extern int array[66] in another source file. This is clearly wrong, but my doubt is how the compiler compiled it. It should have thrown error. In case if it compiles then what will be the behavior of the system? Will it be normal or some undefined behavior?
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Jul 14, 2014
I have some files:
file1: 1000x500 array of numbers
file2: 2000x600
file3: 300x5000
...
I would like to automatically declare array variables of myarray1, myarray2, myarray3... that reads the numbers from files:
Code:
for (i1=0; i1<nrows; i1++)
{
for (i2=0; i2<ncolumns; i2++)
{
fscanf(filename, "%lf", &y);
myarrayX[i1][i2]=y;
}
}
nrows and ncolumns can be passed from a config file. Also I can cat all files into a single filename. However, the difficult part is:
How to declare different myarrayX automatically ? (A workaround is to declare a huge 3d array but I do not want to do this).
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Jan 30, 2013
I am attempting to declare an array of pointers dynamically based on user input. I am not sure if A) I'm implementing the syntax of declaring a dynamic array correcntly and B) if my code is set up correctly to print otherwise.
int array_size;
cout << "Please enter the size of the array: " << endl;
cin >> array_size;
if(array_size >= 8) {
cout << "Invalid array size, please enter a valid integer size";
cin >> array_size;
[Code] .....
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Mar 28, 2013
I'm having trouble declaring and initializing a two-dimensional array using the C++11 standard conventions. I would like to know how to do it in C++11 style as know how to use the old style.
the exception im getting is:
c++11_array_exp.cpp:37:3: error: too many initializers for ‘std::array<std::array<std::basic_string<char>, 6ul>, 22ul>’
you can find my code here:
[URL]
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Aug 3, 2013
i am using c language to program PIC micro controllers, i am making a multi compilation unit project in order to organize my code better.
I want to create an array of functions and be able to call it from anyplace in the code
what i have done so far gplib.c
Code:
typedef void (*out)(int8);
void OUT_A(int8 weight){output_A(weight);}
void OUT_B(int8 weight){output_B(weight);}
void OUT_C(int8 weight){output_C(weight);}
void OUT_D(int8 weight){output_D(weight);}
void OUT_E(int8 weight){output_E(weight);}
out output_port[5+1] = {OUT_A, OUT_B, OUT_C, OUT_D, OUT_E};
how to declare them in gplib.h and how to call them anywhere in the code.
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Jan 23, 2014
Here's my program: - Program which inputs a string from user, reverses it and displays it.
#include <iostream>
using namespace std;
void string_reverse (char [], const int);
int main() {
const int arraysize = 10;
char string[arraysize];
[Code] ....
In the string_reverse function, I have declared temp character type array but on line 38, the
compiler is throwing 3 errors: -
error C2057: expected constant expression
error C2466: cannot allocate an array of constant size 0
error C2133: 'temp' : unknown size
I have declared a constant integer arraysize in line 35. Now I have no clue why is this happening because I think as I have declared it as a constant integer variable, this should not happen.
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May 19, 2013
I'm trying to store an array of vectors using a double pointer as a 2D array, but after the first "vector" (column) has been filled, I get a segfault. I correctly included all the libraries needed, and declared all the variables; I am using this function to allocate the space for the array:
double **vec_array(int rows,int clms)
/*allocates a double matrix with -rows- rows and -clms- columns */
{
int i;
double **m;
[Code].....
I get no error while compiling, but when I run the program I get a segfault right after having read the first vector: switching on the check I get in my output just the components of the first vector and then the segfault:
Terminal:
$ ./myprog input_data.dat
0.000000 0.512468 -0.152468
Segmentation fault (core dumped)
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Oct 11, 2014
I am trying to make a menu program and was wondering if there is a way to declare something more than once without using a different word.
ex.
#include <iostream>
using namespace std;
double grams, ounces, inches, feet, meters; //units to convert
int choice; //menu choice
int main() {
cout << "Welcome to Measurement Converter" << endl;
[Code] .....
I dont really know how to explain it but im trying to use int choice to make choose a program from a simple list.
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Mar 16, 2013
Can we use using declaration within name space scope? is it safe to use it?
I think we can use using declaration for class scope and function scope only.
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Aug 31, 2013
I am trying to understand the behavior of following code. Basically how does printf() prints the value rather than address.
Does initializing value to a pointer during declaration makes a difference when assigned from a variable?
Code:
1 #include <stdio.h>
2
3 int main() {
4 const char *var1 = 'A';
5 int *vint = 10;
[Code] ....
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May 11, 2013
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?
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Feb 17, 2013
I've included <cstddef> into a project of mine in favour of <stddef.h>. When I tried to compile my project, I get 50+ errors stating that types such as "::size_t", "::div_t" and "::abort( )" have not been declared even though <cstddef> includes <stddef.h>.
I've tried searching both the global namespace and the standard namespace, but neither way works. At this moment in time, I don't have any compiler options enabled that may affect the way identifiers are defined, C++11 isn't enabled (which doesn't affect the <cstddef> header anyway), the project is a C++ project, and I've tried using the plain old <stddef.h> header, but the problems still persist.
I'm using GNU's C++ compiler ("__GNUG__" is defined).
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Jan 20, 2013
What is the difference between:
const int testFunction() &
int testFunction() const
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Jul 25, 2013
I have recently found this article: URL.....In their example, by declaring variables in other order, they saved 8 bytes. However, shouldn't compiler take care of it? Is it true, and should I declare variables more carefully?
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Oct 4, 2014
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?
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Jan 24, 2014
I've got some problems with the declaration of a bitset container in my class
I've got a class A and want to have a bitset container in it, whose size just get's defined when running an instance of this class:
#include <bitset>
class A {
bitset <n> bc;
A(int n) : n(n) {};
};
Something like that.
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Aug 2, 2014
#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()'|
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Dec 20, 2013
Code:
struct foo {
char label[64];
int state;
} bar[3] = { };
Will the above code ALWAYS initialize to 0 all objects:
bar[0].label
bar[0].state
bar[1].label
bar[1].state
bar[2].label
bar[2].state
Using gcc and g++, it does in my testing But was wondering if it can be unsafe under some circumstances.
I even tried without = { } and it is still initialized to 0 for all objects!
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Feb 28, 2015
I want to access the body of the Add() of a list in c# to see how it works, but it only just gives me the declaration.
[DebuggerTypeProxy(typeof (Mscorlib_CollectionDebugView<>))]
[DebuggerDisplay("Count = {Count}")]
[Serializable]
public class List<T> : IList<T>, ICollection<T>, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>, IEnumerable<T>, IEnumerable {
public void Add(T item); // thats all. I tried go to declaration but still gives me this line of code. This is from metadata in Visual studio.
}
How this thing work. It just a declaration not a definition yet its still doing something. How is that possible.
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