The post decrement also requires an lvalue. The difference with predecrement is that predecrement returns an lvalue while post decrement returns an rvalue.

what i think is we are assigning only 1 byte in Heap and input is more than 1 byte so is this wrong ?

You are right.

even it prints good morning but it still is logical error ?

Its a out of range error, a type of logic error.

as a good programmer we should not use or play with unallocated memory

#include<stdio.h> #include<stdlib.h> int main() { char *ptr[2] ; for(int i=0; i<2; i++) { ptr[i] = (char *)malloc( 1 ); printf("Enter the %d string \n", i+1); scanf("%s", ptr[i] ); } for(int i=0; i<2; i++) printf("\n%s", ptr[i] )

It so happens that in this case the heap allocations for both the pointers happened in relatively far away locations. But assume that they had been allocated next to each other. In that case when you input the second string, you will overwrite the previous string you had input and the output would be jumbled up. It is precisely for this reason that it is Undefined Behavior.

so basically this we should not use or play with unallocated memory ?

so basically this we should not use or play with unallocated memory ?

#include<iostream> using namespace std; class node{ public: int data; node* next; node* prev; node(int val){ data=val; next=NULL; prev=NULL; } }; void insert(node* &head,int val){ node* n=new node(val); node* temp=head; if(head==NULL){ head=n; return; } else{ while(temp->next!=NULL){ temp=temp->next; } temp->next=n; n->prev=temp; } } void display(node* head){ node* temp=head; if(head==NULL){ cout<<"list is empty"<<endl; } else{ while(temp!=NULL){ cout<<temp->data<<"->"; temp=temp->next; } cout<<"NULL"<<endl; } } void alternatedel(node* &head){ node* temp=head; while(temp->next->next!=NULL && temp->next!=NULL){ temp->next=temp->next->next; temp->next->next->prev=temp; temp=temp->next->next; } temp->next=NULL; } int main(){ node* head=NULL; insert(head,1); insert(head,2); insert(head,3); insert(head,4); insert(head,5); insert(head,6); display(head); alternatedel(head); display(head); return 0; }

Your while loop condition should be while(temp!= NULL && temp->next != NULL && temp->next->next != NULL) Not sure if this is the only problem but this is definitely a problem

Your while loop condition should be while(temp!= NULL && temp->next != NULL && temp->next->next != NULL) Not sure if this is the only problem but this is definitely a problem

#include<iostream> using namespace std; class node{ public: int data; node* next; node* prev; node(int val){ data=val; next=NULL; prev=NULL; } }; void insert(node* &head,int val){ node* n=new node(val); node* temp=head; if(head==NULL){ head=n; return; } else{ while(temp->next!=NULL){ temp=temp->next; } temp->next=n; n->prev=temp; } } void display(node* head){ node* temp=head; if(head==NULL){ cout<<"list is empty"<<endl; } else{ while(temp!=NULL){ cout<<temp->data<<"->"; temp=temp->next; } cout<<"NULL"<<endl; } } void alternatedel(node* &head){ node* temp=head; while(temp->next->next!=NULL && temp->next!=NULL){ temp->next=temp->next->next; temp->next->next->prev=temp; temp=temp->next->next; } temp->next=NULL; } int main(){ node* head=NULL; insert(head,1); insert(head,2); insert(head,3); insert(head,4); insert(head,5); insert(head,6); display(head); alternatedel(head); display(head); return 0; }

While, Do while & For. 3 condition we can use.

Read my message again

#include<iostream> using namespace std; class node{ public: int data; node* next; node* prev; node(int val){ data=val; next=NULL; prev=NULL; } }; void insert(node* &head,int val){ node* n=new node(val); node* temp=head; if(head==NULL){ head=n; return; } else{ while(temp->next!=NULL){ temp=temp->next; } temp->next=n; n->prev=temp; } } void display(node* head){ node* temp=head; if(head==NULL){ cout<<"list is empty"<<endl; } else{ while(temp!=NULL){ cout<<temp->data<<"->"; temp=temp->next; } cout<<"NULL"<<endl; } } void alternatedel(node* &head){ node* temp=head; while(temp->next->next!=NULL && temp->next!=NULL){ temp->next=temp->next->next; temp->next->next->prev=temp; temp=temp->next->next; } temp->next=NULL; } int main(){ node* head=NULL; insert(head,1); insert(head,2); insert(head,3); insert(head,4); insert(head,5); insert(head,6); display(head); alternatedel(head); display(head); return 0; }

And dont use NULL in C++. Use nullptr or use 0 if you have a pre C++11 compiler

But that didn't created any problems before

And the last line in while loop should be temp = temp->next;

In which func?

I think there is some other mistake too

And the last line in while loop should be temp = temp->next;

But I think after the while loop ends you are in the last node that means the next of the last node should be null .

Sorry was away. Try this instead: https://pastebin.com/TLzsthrt (Simplified it further). I havent tested it. So see if it works and let me know.

that was completely wrong

You mean my function was wrong. Let me test it.

You mean my function was wrong. Let me test it.

Sorry was away. Try this instead: https://pastebin.com/TLzsthrt (Simplified it further). I havent tested it. So see if it works and let me know.

I mean my earlier code was completely wrong

This is the code btw : https://pastebin.com/TLzsthrt

Okay .thank you

Can anyone suggest me about what are the projects needed to be placed in a product based company I have no knowledge about what actually a project is.

If I have: int *mypointer; cout << &mypointer << endl; cout << mypointer << endl; What is the difference between these two?? The first gives you the address of the pointer, yes? What is the second?

The first one print the address of mypointer. The second print the adress of the object mypointer point to. You should initialize the pointer until you use it (particularly on local scope).

That makes sense so &mypointer prints the pointer to the pointer.

Nop. int *mypointer is a pointer to an object of type int. You can write pointer to a pointer as: type **mypointer;

template<typename T> concept Equal = requires(T a, T b) { { a == b } -> std::convertible_to<bool>; { a != b } -> std::convertible_to<bool>; };

I know that this is a definition of a concept but could someone explain to me the syntax of these two lines: { a == b } -> std::convertible_to<bool>; { a != b } -> std::convertible_to<bool>;

hello guys, i'm not able to open a .bat file using c language does anyone have any idea what it could be?

Does system("<name.bat>") not help?

broo, The syntax of the command is incorrect.

Can you share the code of the program? Also can you describe what "doesn't work" means in this case? Does it crash immediately? Or print something before crash?

It was a console based app. I compiled it on a 64bit and executed on a 32 bit computer.

It was a console based app. I compiled it on a 64bit and executed on a 32 bit computer.

This is the code btw : https://pastebin.com/TLzsthrt

You forgot to delete the discarded nodes. https://pastebin.com/qAzdTRSa

you need to add -m32 flag when you compile it.

The OP didnt do deletion in her program. So I didnt either. Just modified the OP's pointer code.

But I don't use gcc much due to using an ide. I use clion and it compiles the code for me. So how can I use the flag?

But I don't use gcc much due to using an ide. I use clion and it compiles the code for me. So how can I use the flag?

See this. https://www.jetbrains.com/help/clion/cmake-profile.html#compiler-flags

sorry i never use clion ide.

Why?