Deallocate memory to singleton class which access database ?

Qt embedded developer

@jsulm Okay thanks. but still i am getting below errors:

"src\SqliteManagerBGSync.cpp", line 27: Error: #260-D: explicit type is missing ("int" assumed)
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #252: reference variable "kv" requires an initializer
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #65: expected a ";"
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #29: expected an expression
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #65: expected a ";"
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 28: Error: #153: expression must have class type
delete kv.second;

KroMignon

@Qt-embedded-developer said in Deallocate memory to singleton class which access database ?:

Okay thanks. but still i am getting below errors:

Do your compiler support C++11 and did you enable C++11 support (eg. add CONFIG += c++11 in your PRO file)?

Qt embedded developer

@KroMignon Hi i am not using qt . and sorry i can not enable C++ 11 because my compiler not support it. i can access map like std::map .

J.Hilk

@Qt-embedded-developer

SqliteManagerBGSync();
cleanup();

both are missing the return type, and also make sure to fix them in the *.cpp file as well!

Qt embedded developer

@J-Hilk i have changed it . i have used void, But still i am getting as below mentioned error:

"src\SqliteManagerBGSync.cpp", line 27: Error: #260-D: explicit type is missing ("int" assumed)
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #252: reference variable "kv" requires an initializer
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #65: expected a ";"
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #29: expected an expression
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 27: Error: #65: expected a ";"
for (const auto& kv : sqliteManagerMap) {
^
"src\SqliteManagerBGSync.cpp", line 28: Error: #153: expression must have class type
delete kv.second;

jsulm

@Qt-embedded-developer As @KroMignon already asked you: do you have a C++11 capable compiler? And is C++11 activated?

Qt embedded developer

@jsulm no i have not. So what i have to change in below function:

SqliteManagerBGSync::cleanup()
{
for (const auto& kv : sqliteManagerMap) {
    delete kv.second;
}
sqliteManagerMap.clear();

}

KroMignon

@Qt-embedded-developer said in Deallocate memory to singleton class which access database ?:

Hi i am not using qt . and sorry i can not enable C++ 11. i can access map like std::map .

The problem is not std::map<>() but the way you iterate through the map: for (const auto& kv : sqliteManagerMap) requires at least C++11 support enabled! (cf. https://en.cppreference.com/w/cpp/container/map)

I don't know which kind of C++ compiler you are using, for GCC for example enabling C++11 is done with -std=c++11 or -std=gnu++11

jsulm

@Qt-embedded-developer Then you can't use auto, write the type instead of auto

Qt embedded developer

@KroMignon i can not enable it like that because any change like that not allowed in my device.

J.Hilk

@Qt-embedded-developer than do a normal for(x; x<y; ++x) loop

Qt embedded developer

@J-Hilk ,@jsulm ,@jsulm ,@KroMignon Thanks for enormous support.

i have written like it below and now its not show any error:

void SqliteManagerBGSync::cleanup()
{
for (short int i =0 ; i<sizeof(sqliteManagerMap);i++)
{
    delete sqliteManagerMap[i];
}
sqliteManagerMap.clear();

}

J.Hilk

@Qt-embedded-developer
using sizeof is almost certainly wrong here.

std::map has a size() function, please use that.
https://en.cppreference.com/w/cpp/container/map/size

KroMignon

@Qt-embedded-developer said in Deallocate memory to singleton class which access database ?:

i can not enable it like that because any change like that not allowed in my device.

As @jsulm already wrote before, replace auto with the corresponding type:

for(std::map<int,SqliteManagerBGSync*>::iterator it = sqliteManagerMap::begin(); it != sqliteManagerMap::end(); ++it)
{
...
}

J.Hilk

@KroMignon ~~IIRC range based for loops is a c++11 feature in itself 🤔~~

never mind, I think need a break!

KroMignon

@J-Hilk said in Deallocate memory to singleton class which access database ?:

IIRC range based for loops is a c++11 feature in itself 🤔

Are you sure? I don't believe that std::map<>::iterator support is comming with C++11.

jsulm

@KroMignon I think @J-Hilk misunderstood your code: you are not using range based loop

Qt embedded developer

@KroMignon Here inside for loop i need to write

for(std::map<int,SqliteManagerBGSync*>::iterator it = sqliteManagerMap::begin(); it != sqliteManagerMap::end(); ++it)
{
delete it;
}

or what i need to write to deallocate memory ?

jsulm

@Qt-embedded-developer said in Deallocate memory to singleton class which access database ?:

delete it;

delete it->second;

of course

KroMignon

@Qt-embedded-developer said in Deallocate memory to singleton class which access database ?:

or what i need to write to deallocate ?

Please, take time to read std::map<> documentation.
You are using a map iterator, so it is a container object which gives you access to key and value.

delete it do not make sense!

You want to delete the pointer hold in the value part: delete it->second