The other documents in the group are: Closed Issues Listwhich contains the issues which the Committee has decided are not defects in the International Standard, including a brief rationale explaining the reason for the decision. Defect Reports Listwhich contains the issues that have been categorized by the Committee as Defect Reports, as well as other issues accepted by the Committee, along with their proposed resolutions.
WPbytes in sizeas compiled in the small model with Borland and Microsoft compilers with optimization on opt and off no opt. ASM ; Assembler subroutine to perform a bit checksum on the file ; opened on the passed-in handle.
Stores the result in the ; passed-in checksum variable. Returns 1 for success, 0 for error. Optimization makes code faster, but without proper design, optimization just creates fast slow code.
Well, then, how are we going to improve our design? Know the Territory Just why is Listing 1. The C library implements the read function by calling DOS to read the desired number of bytes. I figured this out by watching the code execute with a debugger, but you can buy library source code from both Microsoft and Borland.
That means that Listing 1. For starters, DOS functions are invoked with interrupts, and interrupts are among the slowest instructions of the x86 family CPUs. Then, DOS has to set up internally and branch to the desired function, expending more cycles in the process.
Finally, DOS has to search its own buffers to see if the desired byte has already been read, read it from the disk if not, store the byte in the specified location, and return. All of that takes a long time—far, far longer than the rest of the main loop in Listing 1.
In short, Listing 1. You can verify this for yourself by watching the code with a debugger or using a code profiler, but take my word for it: How can we speed up Listing 1.
It should be clear that we must somehow avoid invoking DOS for every byte in the file, and that means reading more than one byte at a time, then buffering the data and parceling it out for examination one byte at a time. The results confirm our theories splendidly, and validate our new design.
As shown in Table 1. To the casual observer, read and getc would seem slightly different but pretty much interchangeable, and yet in this application the performance difference between the two is about the same as that between a 4. Make sure you understand what really goes on when you insert a seemingly-innocuous function call into the time-critical portions of your code.
In other words, know the territory! Spend your time improving the performance of the code inside heavily-used loops and in the portions of your programs that directly affect response time. Let C do what it does well, and use assembly only when it makes a perceptible difference. Always Consider the Alternatives Listing 1.
Like readgetc calls DOS to read from the file; the speed improvement of Listing 1. Easier, yes, but not faster. Every invocation of getc involves pushing a parameter, executing a call to the C library function, getting the parameter in the C library codelooking up information about the desired stream, unbuffering the next byte from the stream, and returning to the calling code.
That takes a considerable amount of time, especially by contrast with simply maintaining a pointer to a buffer and whizzing through the data in the buffer inside a single loop.
There are four reasons that many programmers would give for not trying to improve on Listing 1.
The code is already fast enough.In the above program the data member radius is public so we are allowed to access it outside the class. Private: The class members declared as private can be accessed only by the functions inside the class.
What do you think this program will output? Let’s look at how this works. First, we instantiate a C class object. rBase is an A reference, which we set to reference the A portion of the C object.
Tip: You can modify the classpath from within BeanShell using the addClassPath() and setClassPath() commands.
base has three member variables: x, y and z which are public, protected and private member respectively. publicDerived inherits variables x and y as public and protected.
z is not inherited as it is a private member variable of base. Access modifiers in java or java access modifiers such as private, default, protected and public with examples applied on data member, method, constructor or class.
The protected access modifier is accessible within package and outside the package but through inheritance only. Access specifiers defines the access rights for the statements or functions that follows it until another access specifier or till the end of a class.
The three types of access specifiers are "private", "public", "protected".