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int x;
x=x+30;
cout << x;
the output will be 33, why is it so?
I didn't even declare x as 3.
Can someone guides me? Thanks!
Using an uninitialized variable is undefined behavior. You got 33 due to an unreliable sequence of implementation quirks. The program is free to produce any value at all, fail to compile, or hire an assassin to stab you.
In C++, variables are given space (memory allocation) by default equal to the size of the variable, but they are not given values by default.
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While debugging I found in "else if" part the if(temp->parent==temp1) statement is not checking true or false. Control directly jumps to the Send() function. Please let me know where it is going wrong.
else if(I_Send(my_rank,global_parent,&dest,num_procs))
{
if(temp->parent==temp1)
{
fix_node[my_rank]==temp;
}
Send(fix_node[my_rank],L,sz_vec[fix_node[my_rank]->node_num],fix_node[my_rank],dest,temp1);
temp1=temp1->parent;
if(temp1!=NULL)
local_parent=temp1->node_num;
}
The code inside the if body has no effect...
fix_node[my_rank]==temp;
I think you meant to do an assignment (=) instead of comparison (==)
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I need to write a program that will perform operations on float numbers higher than 10^100.
I can't use any arbitrary precision mathematics libraries that are not included in GCC package by default.
I have NO idea how how to go about it.
Can you point me in the right direction?
You can create a class that can store larger numbers. 12345678 equals to 1234 * 10e4 + 5678.
For large numbers I use string buffers and do manual computation on it. It is much overhead and slow but you get infinite precision.
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return this->
what is that mean in C++
..
using namespace std;
IOM ConfigurationManager::getIOM(int iomId) {
return this->IOMs[iomId];
..
the relevant part of the whole code is above.
The code that I wrote is from a huge project which was waiting for someone to finish. I am not good at C++ but I need to learn more not to lose that job. Anyway, the project is full of "return this->...." which I thought unnecessary, that's why I asked is there smt special that we should use that notation
This piece of code simply means that the IOM at index iomId in the IOMs array in the ConfigurationManager object is returned. Note that the this->IOMs is the same as IOMs in this case, thus it seems the this is only there for clarity.
this is a pointer to the current object. The -> operator allow you to access a member inside a pointer to an object.
Thus return this->IOMs[iomID] returns the IOM object in the current ConfigurationManager at index iomID.
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I have a 2500 line and 76.8 kb c++ console program. I learned inline function but heard about inline function makes a trouble in huge programs. Is it true? This program is huge or not. It can be a trouble in the future. What should i do or what is your suggestion for me.
Note:Program include lots of functions.
Thanks!
Is it true?
You can check out the advantage and disadvantages of Inline Functions and justify it
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In C/C++, I was wondering which is faster?
int a;
int b = a + a; // this
int b = 2 * a; // or this?
Also, is important the datatype? What about long? what about the number of times we add up?
(what about...)
long a;
long b = a + a + a +a;
long b = 4 *a;
Trust your optimizing compiler. It knows how to optimize for a specific CPU/architecture in ways that you will only be able to guess. Without reference to a specific architecture, there is no meaning to statements like "is x faster than y?", because it all depends on a huge number of factors.
And as always with performance questions, measuring is going to answer the question more completely than us offering semi-informed opinions and guesses.