Memory errors when calling variable

-1

I'm getting different errors that are always related to the memory (this current set throws memory violation exception) when I pass a pointer to a function.

I tried various implementations to solve the problem but nothing worked.

Here is the code:
In class:

class OpenFileDialog 
public:
 OpenFileDialog();
 ~OpenFileDialog();
 static bool BrowseFiles(wstring* fileName) OFN_FILEMUSTEXIST;
 if (GetOpenFileNameW(&ofn)) 
 return true;
 else 
 return false;
 
;

Method calling:

try 
 wstring fileName;
 if (OpenFileDialog::BrowseFiles(&fileName)) 
 A(fileName); // erros here
 else 
 A(_T("Failed"));
 
 catch (bad_alloc) 
 A(L"Bad allocation");

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

1

And what is A?

– Yksisarvinen
Nov 16 '18 at 10:00

Just a function that prints the passing variable in a messageBox. However, thats not the issue since. I used the function multiple times.

– Vinícius Gabriel
Nov 16 '18 at 10:02

The debugger stack trace is very important. GetOpenFileName() and friends are risky, they load shell extensions in your process. Programmer machines tend to have a lot of them, not always of the best quality. If one of them misbehaves then the debugger will see it.

– Hans Passant
Nov 16 '18 at 10:09

add a comment |

-1

class OpenFileDialog 
public:
 OpenFileDialog();
 ~OpenFileDialog();
 static bool BrowseFiles(wstring* fileName) OFN_FILEMUSTEXIST;
 if (GetOpenFileNameW(&ofn)) 
 return true;
 else 
 return false;
 
;

Method calling:

try 
 wstring fileName;
 if (OpenFileDialog::BrowseFiles(&fileName)) 
 A(fileName); // erros here
 else 
 A(_T("Failed"));
 
 catch (bad_alloc) 
 A(L"Bad allocation");

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

1

And what is A?

– Yksisarvinen
Nov 16 '18 at 10:00

Just a function that prints the passing variable in a messageBox. However, thats not the issue since. I used the function multiple times.

– Vinícius Gabriel
Nov 16 '18 at 10:02

The debugger stack trace is very important. GetOpenFileName() and friends are risky, they load shell extensions in your process. Programmer machines tend to have a lot of them, not always of the best quality. If one of them misbehaves then the debugger will see it.

– Hans Passant
Nov 16 '18 at 10:09

add a comment |

-1

class OpenFileDialog 
public:
 OpenFileDialog();
 ~OpenFileDialog();
 static bool BrowseFiles(wstring* fileName) OFN_FILEMUSTEXIST;
 if (GetOpenFileNameW(&ofn)) 
 return true;
 else 
 return false;
 
;

Method calling:

try 
 wstring fileName;
 if (OpenFileDialog::BrowseFiles(&fileName)) 
 A(fileName); // erros here
 else 
 A(_T("Failed"));
 
 catch (bad_alloc) 
 A(L"Bad allocation");

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

class OpenFileDialog 
public:
 OpenFileDialog();
 ~OpenFileDialog();
 static bool BrowseFiles(wstring* fileName) OFN_FILEMUSTEXIST;
 if (GetOpenFileNameW(&ofn)) 
 return true;
 else 
 return false;
 
;

Method calling:

try 
 wstring fileName;
 if (OpenFileDialog::BrowseFiles(&fileName)) 
 A(fileName); // erros here
 else 
 A(_T("Failed"));
 
 catch (bad_alloc) 
 A(L"Bad allocation");

c++ winapi

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

asked Nov 16 '18 at 9:58

Vinícius Gabriel

151110

1

And what is A?

– Yksisarvinen
Nov 16 '18 at 10:00

Just a function that prints the passing variable in a messageBox. However, thats not the issue since. I used the function multiple times.

– Vinícius Gabriel
Nov 16 '18 at 10:02

The debugger stack trace is very important. GetOpenFileName() and friends are risky, they load shell extensions in your process. Programmer machines tend to have a lot of them, not always of the best quality. If one of them misbehaves then the debugger will see it.

– Hans Passant
Nov 16 '18 at 10:09

add a comment |

1

And what is A?

– Yksisarvinen
Nov 16 '18 at 10:00

Just a function that prints the passing variable in a messageBox. However, thats not the issue since. I used the function multiple times.

– Vinícius Gabriel
Nov 16 '18 at 10:02

The debugger stack trace is very important. GetOpenFileName() and friends are risky, they load shell extensions in your process. Programmer machines tend to have a lot of them, not always of the best quality. If one of them misbehaves then the debugger will see it.

– Hans Passant
Nov 16 '18 at 10:09

And what is A?

– Yksisarvinen
Nov 16 '18 at 10:00

Just a function that prints the passing variable in a messageBox. However, thats not the issue since. I used the function multiple times.

– Vinícius Gabriel
Nov 16 '18 at 10:02

The debugger stack trace is very important. GetOpenFileName() and friends are risky, they load shell extensions in your process. Programmer machines tend to have a lot of them, not always of the best quality. If one of them misbehaves then the debugger will see it.

– Hans Passant
Nov 16 '18 at 10:09

add a comment |

1 Answer
1

active

oldest

votes

The cast LPWSTR((*fileName).c_str()) should be a hint that you do something wrong.

The string fileName is empty, it doesn't have any memory allocated for it. Calling c_str() will return a pointer to a constant string of zero characters.

So there are two errors: You try to write data to memory that doesn't exist; And even if it did it would be constant and not modifiable anyway. Both leading to undefined behavior.

You need to create a temporary array of characters, large enough to hold the longest path possible, and then initialize fileName to that string after GetOpenFileNameW succeeds.

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

add a comment |

Your Answer

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53335384%2fmemory-errors-when-calling-variable%23new-answer', 'question_page');

);

Post as a guest

Name

Required, but never shown

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

The cast LPWSTR((*fileName).c_str()) should be a hint that you do something wrong.

The string fileName is empty, it doesn't have any memory allocated for it. Calling c_str() will return a pointer to a constant string of zero characters.

So there are two errors: You try to write data to memory that doesn't exist; And even if it did it would be constant and not modifiable anyway. Both leading to undefined behavior.

You need to create a temporary array of characters, large enough to hold the longest path possible, and then initialize fileName to that string after GetOpenFileNameW succeeds.

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

add a comment |

The cast LPWSTR((*fileName).c_str()) should be a hint that you do something wrong.

The string fileName is empty, it doesn't have any memory allocated for it. Calling c_str() will return a pointer to a constant string of zero characters.

So there are two errors: You try to write data to memory that doesn't exist; And even if it did it would be constant and not modifiable anyway. Both leading to undefined behavior.

You need to create a temporary array of characters, large enough to hold the longest path possible, and then initialize fileName to that string after GetOpenFileNameW succeeds.

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

add a comment |

The cast LPWSTR((*fileName).c_str()) should be a hint that you do something wrong.

The string fileName is empty, it doesn't have any memory allocated for it. Calling c_str() will return a pointer to a constant string of zero characters.

So there are two errors: You try to write data to memory that doesn't exist; And even if it did it would be constant and not modifiable anyway. Both leading to undefined behavior.

You need to create a temporary array of characters, large enough to hold the longest path possible, and then initialize fileName to that string after GetOpenFileNameW succeeds.

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

The cast LPWSTR((*fileName).c_str()) should be a hint that you do something wrong.

The string fileName is empty, it doesn't have any memory allocated for it. Calling c_str() will return a pointer to a constant string of zero characters.

So there are two errors: You try to write data to memory that doesn't exist; And even if it did it would be constant and not modifiable anyway. Both leading to undefined behavior.

You need to create a temporary array of characters, large enough to hold the longest path possible, and then initialize fileName to that string after GetOpenFileNameW succeeds.

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

answered Nov 16 '18 at 10:04

Some programmer dude

304k25265426

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

add a comment |

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

SO users tend to post the last version of the code they tried. It was the only "memory error" cause he could think of. It ain't it.

– Hans Passant
Nov 16 '18 at 10:12

A temporary C-style character array is not needed. fileName->resize(MAX_PATH); ofn.lpstrFile = fileName->data();. This requires C++17 for non-const data(). C++11 allows for fileName->resize(MAX_PATH); ofn.lpstrFile = &fileName[0];. Valid, but less clean.

– zett42
Nov 16 '18 at 12:16

add a comment |

draft saved

draft discarded

Thanks for contributing an answer to Stack Overflow!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

搜尋此網誌

Myujth