- SWITCH CASE IN TURBO C HOW TO
- SWITCH CASE IN TURBO C CODE
- SWITCH CASE IN TURBO C PLUS
- SWITCH CASE IN TURBO C FREE
But when i=500, just four comparisons are required.Īs we know, the prerequisite of binary search is that the input data is sorted. When i=1, it will pass through the first six comparisons and then reach default at LN1. Essentially, this is a binary search algorithm with the complexity of O(log n). The inorder traversal sequence for comparison nodes is 100, 200, 250, 500, 700, 750, 800, and 900 while the sequence for all leaves in the inorder traversal is exactly LN9, LN8, LN7, LN6, LN5, LN4, LN3, and LN2, as ordered in the previous table. The following shows the equivalent decision tree of above code, a Binary Search Tree that you may be familiar with:įor all internal nodes colored yellow in circle, we make the comparisons, while all leave nodes in oval represent the successful ending. Although this switch is implemented with ten if-then statements for nine conditions, it actually applies the binary search mechanism.
Surely, the compiler optimizes the code, because it first chooses 700 to compare, instead of the beginning case value 100 in the switch block. To simplify, we just make use of all the labels here by removing the leading "$" and the tailing Rewrite the snippet like this: At first, the condition value i is saved in both _i$ and tv64. Mov DWORD PTR tv64, eax cmp DWORD PTR tv64, 700 000002bcH jg SHORT DWORD PTR tv64, 700 000002bcH je SHORT DWORD PTR tv64, 250 000000faH jg SHORT DWORD PTR tv64, 250 000000faH je SHORT DWORD PTR tv64, 100 00000064H je SHORT DWORD PTR tv64, 200 000000c8H je SHORT SHORT DWORD PTR tv64, 500 000001f4H je SHORT SHORT DWORD PTR tv64, 750 000002eeH je SHORT DWORD PTR tv64, 800 00000320H je SHORT DWORD PTR tv64, 900 00000384H je SHORT SHORT logic is not too hard to understand.
SWITCH CASE IN TURBO C CODE
Next, how do we jump to these calling targets? Look at the following code:Ĭopy Code 5 : int i =1 mov DWORD PTR _i$, 1 6 : 7 : switch (i) mov eax, DWORD PTR _i$
SWITCH CASE IN TURBO C PLUS
Pretty neat, with eight cases plus one default, we can easily write this part into a list of nine rows, each corresponding to a target label, a C++ case, and a procedure name:īesides to we also have implement the break statement.
Our first example is switch1.cpp, a commonly used simple block as below:Ĭopy Code 8 : 20 : 21 : return 0 If you are learning Assembly Language Programming, this article might be a study material to read. As you can see shortly, all results here are based on reverse engineering, and so the article is never a comprehensive description of switch implementations in compilers. Thus, a general understanding of Intel (x86) assembly language is assumed. We'll analyze these examples by using the Microsoft Visual Studio IDE, since it can generate the corresponding assembly listing on compiling. This article discusses what happens when running a switch statement in Visual C++, with a few examples under different conditions.
SWITCH CASE IN TURBO C FREE
Every vendor is free to use any implementation as long as it fits the standard.
SWITCH CASE IN TURBO C HOW TO
The C/C++ standard defines the specification of language elements, but it doesn't say anything about how to implement the switch statement.