When any memory Is dynamically allocated then that memory exists from the start of the program till the end of the program and gets released once program ends. Then why is it advised to delete that memory manually? And also if I create an object dynamically, then at the time when program ends why the destructor doesn't run for this dynamically created object?

Because not all programs are meant to run and stop. There are programs that run continuously and in such programs memory leaks can manifest themselves into "Out of Memory" issues. And destructors are run only for objects that go out of scope and objects in the global scope (when the program ends). For objects that are allocated dynamically, only the pointer to it goes out of scope and there is nothing to be done when a pointer goes out of scope except for freeing up the memory which the pointer occupies which is in most cases just a stack pointer reset. So destructors are not called. If your dynamically allocated object had locked an IPC mutex, then this muted will remain locked.

So if I know that I need an object till the end of program, I don't need to write delete statment?

Well technically yes. If you need an object till the end it wouldnt make sense to delete it earlier now would it?

So if I know that I need an object till the end of program, I don't need to write delete statment?

But if that object is acquiring some resources that need to be freed at the end of the program then you must call delete on it to run its destructor.

Those resources won't be deleted automatically when program ends??

What's an IPC mutex

I still can't understand it

No

I trieed int elapsed_time = (hour*60*60) +(min*60)+sec; but i dont get the results i want so is it possible to get the elapse time so i can use it for

Hi all new to programming any help for prerequisite tools for c programming & how to configure it on windows10

If you are new to C, start with Visual Studio Community Edition if you have the bandwidth for gigabytes of download. If not, download mingw package installer from msys2 website (this apparently offers the latest version of the compiler tools) and download an IDE like CodeBlocks or CLion (if you are a student) and configure it with the path to your mingw installation. Use one of these books : 1. Modern C by Jen Gustedt 2. Modern C by KN King 3. The C programming Language by Kernighan and Ritchie and fire away.

A silly question but what would i be missing if i use simple text editors like sublime, codeblocks or VS code instead of VS(full version)?

A silly question but what would i be missing if i use simple text editors like sublime, codeblocks or VS code instead of VS(full version)?

I recommend starting only with a text editor and compiling with the terminal

If anyone help For vscode installation it's helpful because organization is use it. For C specific

int main() { int arr[5] = {1,2,3,4,5}; for (int i=0; i!=5; i++) { std:: cout<<arr[i]; } return 0; } Is there any difference if I replace i!=5 with i<5 in the for loop ? Not asking in terms of output.

Theoretically,no difference.But i != 5 looks weird for loop.

I saw a solution, where it had vector<string> v(n); but he was doing this: mymap[v[j][i]]++; Now, I wanna know how come a 1D vector access [j][i]

The first index is on the vector which returns a string and the second index is on the string returned. So v[j] gets the string at index j and v[j][i] gets the i'th character from the string at index j in the vector.

i'm a bit confused :/

It is the equivalent of this code. string s = vec[j]; char c = s[i]; This is equivalent to char c = vec[j][i];

so originally, the vector contained strings right suppose it had: { "abcd" , "efgh", "ijkl" }; now, let's say, j = 1 then, s = efgh and let's say, i= 0 then, c = e Am I correct?

Yes

So we can use that for any "container" - the v[j][i] style?

If the container elements support indexing then yes. For ex: vector<vector<int>> vec = ....; You can do vec[i][j] to acces the j'th element in the i'th vector in vec.

yes ik that but this was an 1D vector

The first index applies to the vector. The second index applies to the element in the vector. There is nothing like a 2D vector. A vector is a sequence of elements. That is it. Now whether you can apply a second index depends on the type of the elements in the vector. If the element is a string, a deque or a vector or a std::array or any class that overloads operator[], then you can use a 2nd index. This can be extended further.

when we look at very low level ?

int main() { int arr[5] = {1,2,3,4,5}; for (int i=0; i!=5; i++) { std:: cout<<arr[i]; } return 0; } Is there any difference if I replace i!=5 with i<5 in the for loop ? Not asking in terms of output.

Basically no difference here. Personally, I prefer i!=5. It implies i=5 when the loop ends. While another implies i>=5.

C++ developers generally prefer != over < because it is what is used with iterators as well. Not all iterators support < but all iterators support !=.

int main() { int arr[5] = {1,2,3,4,5}; for (int i=0; i!=5; i++) { std:: cout<<arr[i]; } return 0; } Is there any difference if I replace i!=5 with i<5 in the for loop ? Not asking in terms of output.

I often use < rather than != because I get slightly baselessly worried that is it were to somehow miss that stage it'd run forever, never to be stopped again with !=

https://code.visualstudio.com/docs/languages/cpp This?

& how to setup vscode for user input , terminal output ,logs

If someone needs help in c ask me dm

Is there any C standard that provides the ability to size an array with a variable. Like this: #include <stdio.h> const int LENGTH = 5; int main() { int array[LENGTH] = { 10, 20, 30, 40, 50 }; }

Can you elaborate? Like, you can initialise the size with any variable (that has a value inputted or smth), and that's not a "global" variable as you declared

Edited Code

...yes and what do you wanna know?

Also you wrote int twice

Any c standard that allows this

Allows what? Global variables?

Any c standard that allows this

should work with c++ and constexpr, in c i've seen people use the preprocessor for this a lot

Yea. That way the code works fine in C

But in case of C, do we have any C standard that allows the same using const int LENGTH instead of #define LENGTH

do you want to determine the size at run-time?

I saw a video related to fixed and variable length arrays in youtube. I'm surprised why didn't his code produced error.

You mean dynamic allocation?