• 0

Dynamic Array in C++ (Please help me I don't understand some code line, somebody please explain them for me)


Question

This is a function to insert A Number at A Position in a dynamic array ;

1/ I don't understand from the line "moveCount". What is moveCount for , and, Why move count = size - index;

2/ what in the function "memmove" in c++

3/ could you please explain the codes from the line "ARROW" to the end ?

Thank you so much for helping me ( I am just a stupid child trying to mess around with code :) )

Untitled.png

Edited by crop_duster

1 answer to this question

Recommended Posts

  • 0

The moveCount var is basically getting the size of the array minus the index of where you want to insert the new value within the array (the function name is DynamicArray::insertAt after all), the if statement makes sure it is an array and if, it's not using memmove to increase the size allocated.

 

http://www.cplusplus.com/reference/cstring/memmove/

 

  Quote

memmove

void * memmove ( void * destination, const void * source, size_t num );

Move block of memory

Copies the values of num bytes from the location pointed by source to the memory block pointed by destination. Copying takes place as if an intermediate buffer were used, allowing the destination and source to overlap.

The underlying type of the objects pointed by both the source and destination pointers are irrelevant for this function; The result is a binary copy of the data.

The function does not check for any terminating null character in source - it always copies exactly num bytes.

To avoid overflows, the size of the arrays pointed by both the destination and source parameters, shall be at least numbytes.

 

Parameters

destination

Pointer to the destination array where the content is to be copied, type-casted to a pointer of type void*.

source

Pointer to the source of data to be copied, type-casted to a pointer of type const void*.

num

Number of bytes to copy.
size_t is an unsigned integral type.

Expand  

 

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • I think the flub is slightly funny, albeit minor. What will be funnier is the people buying some utterly terrible Chinese Android phone for $500 (that's with a huge profit margin worked in). That said, I've bemoaned this before: I miss the days when Neowin was about Microsoft products and technologies and didn't host articles that would get people riled up politically. It used to be a friendlier place where people were only bitches about insignificant things related to Microsoft.
    • AMD thinks Ryzen Threadripper 9000 wipes the floor with Intel by Sayan Sen At Computex 2025 earlier this year, AMD revealed its new Zen 5-based Ryzen Threadripper 9000 series with up to 96 cores, comprising the PRO 9000WX series and 9000 series chips. At the time though the company did not share performance numbers but given the specs, we had a fairly good idea of their capability. For those who may not be familiar with Ryzen Threadripper, it is AMD's desktop CPU lineup meant for workstations and HEDT (high-end desktop) builds and is placed between the mainstream Ryzen and the server EPYC lineups. With the launch expected to happen next month, performance numbers for the Ryzen Threadripper 9000 are now out. Before diving into the performance details, AMD has also shared a recap of some of the platform details and the compatible sTR5 socket. These new premium chips support up to 8 channels of DDR5-6400 memory and up to 128 PCIe 5.0 lanes for I/O. AMD also promises over 7000 MT/s of DDR5 support with EXPO. The specs of the Ryzen Threadripper 9000 lineup are given below: Processor SKU Cores Threads Base Clock (GHz) Boost Clock (GHz) L3 Cache (MB) Memory Channels PCIe Lanes TDP (W) AMD Ryzen Threadripper PRO 9995WX 96 192 2.5 5.45 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper PRO 9985WX 64 128 3.2 5.4 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper PRO 9975WX 32 64 3.2 5.4 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper PRO 9965WX 24 48 3.2 5.4 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper PRO 9955WX 16 32 3.2 5.4 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper PRO 9945WX 12 24 3.2 5.4 384 8‑channel DDR5‑6400 ECC 128 PCIe Gen5 350 AMD Ryzen Threadripper 9980X 64 128 3.2 5.4 256 4‑channel DDR5‑6400 92 PCIe Gen5 350 AMD Ryzen Threadripper 9970X 32 64 3.2 5.4 256 4‑channel DDR5‑6400 92 PCIe Gen5 350 AMD Ryzen Threadripper 9960X 24 48 3.2 5.4 256 4‑channel DDR5‑6400 92 PCIe Gen5 350 AMD has compared the 96-core 9995WX against the previous-gen 7995WX (images below), also with the same core configuration, and the 64-core 9980X, against Intel's 60-core Xeon W9-3595X. While Xeon has generally been associated with Server CPUs, the Xeon W chips are designed to be used in workstations. AMD follows a similar naming, too, wherein the W in the WX is meant to indicate workstation, and the non-W Threadripper is for HEDT. AMD claims up to 26% faster throughput on the newer 96-core 9995WX compared to the 7995WX. Meanwhile, against the Intel Xeon w9-3595X, AMD expects utter dominance from its 9980X with up to 108% faster performance. Even the lowest gain, says the company, is 22% over the Intel chip, and that is still very significant. AMD also compared the AI performance of the 9995WX vs the Xeon w9-3595X. The company promises up to 49% faster LLM processing, but keep in mind that the figures given include a GPU as well. Besides AI, performance related to other creative and professional workloads was also shared. In Keyshot rendering, for example, AMD claims up to 119% gains over the Xeon SKU. And in Chaos V-Ray, the 9995WX is said to offer nearly 2.5 times the performance. AMD has not released pricing information for the Threadripper 9000 series.
    • Funk Microsoft - I would switch from PS5 as you have better deals but the Xbox interface (I tried One S and later on, even one X i hate the interface and considering all MS changes in Windows interface over the years.. I hope they have a good one coming ps5 has also weird interface I had to get used too. But considering the library of ps4 games I wanted to be playable for me… I got used and adapted
    • I loved Sonic CD so much. I think I must have almost worn out that disc!
  • Recent Achievements

    • First Post
      Ian_ earned a badge
      First Post
    • Explorer
      JaviAl went up a rank
      Explorer
    • Reacting Well
      Cole Multipass earned a badge
      Reacting Well
    • Reacting Well
      JLP earned a badge
      Reacting Well
    • Week One Done
      Rhydderch earned a badge
      Week One Done
  • Popular Contributors

    1. 1
      +primortal
      654
    2. 2
      ATLien_0
      267
    3. 3
      Michael Scrip
      218
    4. 4
      +FloatingFatMan
      188
    5. 5
      Steven P.
      146
  • Tell a friend

    Love Neowin? Tell a friend!