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When to use PNG or JPG in iPhone development?
...
PNG's are pixel perfect (non-lossy), and require very little extra CPU energy to display. However, large PNGs may take longer to read from storage than more compressed image formats, and thus be slower to display.
JPG's are smaller to store, but lossy (amount depends on compression level),...
What is the purpose of a stack? Why do we need it?
...It has very good locality of reference, a very important feature on modern CPUs that chew through data a lot faster than RAM can supply it and supports recursion. Language design is heavily influenced by having a stack, visible in support for local variables and scope limited to the method body. A...
小端模式 和 大端模式的决定因素 - C/C++ - 清泛网 - 专注C/C++及内核技术
...和 大端模式的决定因素小端模式 和 大端模式：几乎是由CPU决定的，而非OS或编译器。大端模式和小端模式的区别这里暂不讨论，这里讨论他们是由操作系统、CPU还是编译器决定的呢？
通常来讲，可能大多数人认为是操作系统...
Why is address zero used for the null pointer?
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@GMan - You are correct. On early CPUs, memory address zero was special and had hardware protection against access from running software (in some cases it was the start of the reset vector, and modifying it could prevent the CPU from resetting or starting up)...
Using Java with Nvidia GPUs (CUDA)
...of the matrix. In this case, one can expect that the GPU will outperform a CPU at a certain matrix size. Another example could be when many complex trigonometric computations (sine/cosine etc) are performed on "few" data elements.
As a rule of thumb: You can assume that reading/writing one data el...
Why does my application spend 24% of its life doing a null check?
...uting instructions, it is accessing memory. The execution core of a modern CPU is many times faster than the memory bus. A problem related to distance, the further an electrical signal has to travel, the harder it gets to get that signal delivered to the other end of the wire without it being corrup...
Virtual functions and performance - C++
...curious, so I went ahead and ran some timings on the 3GHz in-order PowerPC CPU we work with. The test I ran was to make a simple 4d vector class with get/set functions
class TestVec
{
float x,y,z,w;
public:
float GetX() { return x; }
float SetX(float to) { return x=to; } // and so on...
How can I check if a Perl array contains a particular value?
...grep, hash...
any: 0 wallclock secs ( 0.67 usr + 0.00 sys = 0.67 CPU) @ 149253.73/s (n=100000)
first: 1 wallclock secs ( 0.63 usr + 0.01 sys = 0.64 CPU) @ 156250.00/s (n=100000)
grep: 42 wallclock secs (41.95 usr + 0.08 sys = 42.03 CPU) @ 2379.25/s (n=100000)
hash: 0 ...
Stack Memory vs Heap Memory [duplicate]
...m C++.
Generally speaking, the stack is preferred as it is usually in the CPU cache, so operations involving objects stored on it tend to be faster. However the stack is a limited resource, and shouldn't be used for anything large. Running out of stack memory is called a Stack buffer overflow. It's...
了解 Boost Filesystem Library - C/C++ - 清泛网 - 专注C/C++及内核技术
...于处理文件系统操作的库，这一直是 C++ 语言存在的一个问题。过去，程序员必须使用本机 API 来解决此问题。通过本文您将了解一个提供安全、可移植且易用的 C++ 接口来促进文件系统操作的库：Boost Filesystem Library。
创建与...