Segmentation Fault (code dumped)

Question

I create two files described below

csvreport.h

int flag = 0; //declared && defined

table.cpp

csvreport* csvreports;
csvreports->flag = 1;

it is showing segmentation fault (code dumped)
any one can give solution for it??

Please provide a mcve: http://stackoverflow.com/help/mcve – Jonas Nov 24 '16 at 08:43 — Jonas, Nov 24 '16 at 08:43

score 5 · Accepted Answer · answered Nov 24 '16 at 08:44

5

csvreport* csvreports; creates uninitialized pointer. Attempt to use uninitialized pointer results in undefined behavior.

Either create this variable on stack, without pointer:

csvreport csvreports;

or, in case if pointer needed - allocate it first:

csvreport* csvreports = new csvreport;
csvreports->flag = 1;

or use unique pointer via modern C++11 way:

auto csvreports = std::make_unique<csvreport>();
csvreports->flag = 1;

answered Nov 24 '16 at 08:44

Starl1ght

4,422
1
21
49

undefined reference to `CSVReports::CSVReports()' – Girdhari Lal Nov 24 '16 at 08:51
@GirdhariLal, my examples are assuming, that you have default constructor. If this is not a case - provide necessary arguments to constructor, or define default one. – Starl1ght Nov 24 '16 at 08:53

score 1 · Answer 2 · answered Nov 24 '16 at 08:44

1

You are trying to access the member of an object using a pointer that has been declared but not initialized to point to anything valid. That is cause for undefined behavior.

Allocate memory for the object first before attempting to access members of the type.

csvreport* csvreports = new csvreport; // or new csvreport[array_size]
csvreports->flag = 1;

answered Nov 24 '16 at 08:44

R Sahu

204,454
14
159
270

undefined reference to `CSVReports::CSVReports()' – Girdhari Lal Nov 24 '16 at 08:49
2

@GirdhariLal, that is an entirely different problem. Create another post for that, with a [mcve]. – R Sahu Nov 24 '16 at 08:50
I used your solution then it is showing this error: undefined reference to `CSVReports::CSVReports()' @R Sahu – Girdhari Lal Nov 24 '16 at 08:54
@GirdhariLal, I understand. I repeat. That is an entirely different problem. Create another post for that, with a [mcve]. – R Sahu Nov 24 '16 at 08:57

score 0 · Answer 3 · edited Nov 24 '16 at 13:12

0

In this code

csvreport* csvreports;
csvreports->flag = 1;

cvsreports is just declared as a pointer; no memory is allocated for it to point to.

edited Nov 24 '16 at 13:12

Toby Speight

27,591
48
66
103

answered Nov 24 '16 at 08:47

Mohan Kumar P

3,122
1
14
17

Segmentation Fault (code dumped)

3 Answers3