C# if directive

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Can I write in code to set the variable to true or false depending on a button I pressed? See example below.

If not, what other ways are there to achieve similar effects? I have already marked the codes for different modes using directives and only want developers to have the option of switching the modes, but now I wish to give the user the option of switching between the modes. The choice of the mode will only be given at the start of the program, and user is not allowed to switch the mode. To switch the mode, he can only restart the program again.

If cannot use directives, what is the fastest way can I use? (note: the statements are all around the solution)

In pseduocode of what I wish to achieve:

void button_click(...){
    if(!CONDITION)
        CONDITION = true;
    else
        CONDITION = false;
}


...
#if CONDITION
   //mode X with addtional steps
#endif

You are using a preprocessor directive and trying to set it from code which defeats the purpose, even if it were to be possible (I'm pretty sure you can't). Why not use a regular boolean field as a flag ?

private bool Condition {get; set;}

C# preprocessor directives, Although the compiler doesn't have a separate preprocessor, the directives described in this section are processed as if there were one. In the C Programming Language, the #if directive allows for conditional compilation. The preprocessor evaluates an expression provided with the #if directive to determine if the subsequent code should be included in the compilation process.

This is not possible. The if statement is executed at run time, but preprocessor directives like #IF are executed at compile time. You need to decide at compile time how to build the code, and somewhere in your project (say in the project's properties) or at the top of the source file, set CONDITION to whatever you need it to be for that given build.

If this really needs to be a runtime decision, then you need to include all the possible code paths and decide at runtime which one to take.

if, #elif, #else, and #endif directives (C/C++), As folks already said, it is a pre-processor directive. Code inside the #if DEBUG #endif will get conditionally compiled, depending on whether  The #if directive, with the #elif, #else, and #endif directives, controls compilation of portions of a source file. If the expression you write (after the #if ) has a nonzero value, the line group immediately following the #if directive is kept in the translation unit.

If your asking if you can conditional compile something based upon a condition in your code the answer is no. The complier must know at compile time what to include in your assembly. You can almost certainly achieve what you are attempting with out conditional compilation however what are you attempting to do?

What is "#if" directive used for in c# and what "symbols" stand for , C# compiler does not have a separate preprocessor; however, the directives are processed as if there was one. In C# the preprocessor directives are used to  Although the compiler doesn't have a separate preprocessor, the directives described in this section are processed as if there were one. They are used to help in conditional compilation. Unlike C and C++ directives, you cannot use these directives to create macros. A preprocessor directive must be the only instruction on a line. See also. C#

The '#IF' directive is used for conditional compilation, which means it looks for tokens defined at compile time and literally compiles or does not compile particular code. This means the non-compiled code is not part of your program and cannot be used at runtime. You will need to modify your code to use normal flags rather than conditional compilation if you want to change behavior at runtime. That said, you may want to consider a deeper design review, as adding new branching functionality based on configuration flags can lead to messy code very quickly.

C# - Preprocessor Directives, C# If Preprocessing Directive: Elif and Endif. Use the if, elif, else and endif preprocessor directives for conditional compilation. If, Elif, Endif. The #if and #​endif  The '#IF' directive is used for conditional compilation, which means it looks for tokens defined at compile time and literally compiles or does not compile particular code. This means the non-compiled code is not part of your program and cannot be used at runtime.

These directives provide the ability to conditionally skip sections of source files, to report error and warning conditions, and to delineate distinct regions of source code You cannot change them at runtime.

C# If Preprocessing Directive: Elif and Endif, Used along with #if to create compound conditional directive. #if preprocessor-​expression code to compile #elif code to compile #endif. #endif  You can use the #if directive to create a conditional directive. Conditional directives are useful for testing a symbol or symbols to check if they evaluate to true. If they do evaluate to true, the compiler evaluates all the code between the #if and the next directive. Syntax for conditional directive is −.

C# Preprocessor directives, The #if directive compiles the code between the directives only if the specified symbol is defined. It is basically used to create a conditional directive. This means  A #region block must be terminated with a #endregion directive. A #region block cannot overlap with a #if block. However, a #region block can be nested in a #if block, and a #if block can be nested in a #region block. See also. C# Reference; C# Programming Guide; C# Preprocessor Directives; Related Articles

Preprocessor Directives in C# [Types and Uses with Example], The C# compiler does not have a separate preprocessor, yet the directives are processed as if there was one. There cannot be anything else in a line other than​  C#. using s = System.Text; using s.RegularExpressions; // Generates a compiler error. Create a using directive to use the types in a namespace without having to specify the namespace. A using directive does not give you access to any namespaces that are nested in the namespace you specify.

Preprocessor Directives in C#, #if, #else, #elif, #endif. These are conditional directives. The #if directive is always enclosed by the #endif directive,  C# If Preprocessing Directive: Elif and Endif. Use the if, elif, else and endif preprocessor directives for conditional compilation. If, Elif, Endif. The #if and #endif directives allow conditional compilation. Along with #elif and #else, these directives add conditions to parts of a source file.

Comments
  • Your question is not clear to me. You want to toggle a member boolean with a button?
  • Maybe the qn wasn't clear... i meant cos the if directives statements are throughout the entire solution which consists of many projects. So i want to find out if there is a shortcut for this to be implemented as a functionality for user by clicking on a button to togger the execution of these statements (not just one but many). Previously the choice to execute these statements or not are just the developer, now i would like the user to have the flexibility to do so as well
  • So what can i do now if i can't use directives? To add to every part of the code with these statements a bool check using a global variable?
  • i hv made more explanation in the qn
  • I don't mean 2 diff states, rather 2 diff modes. One mode just have more statements to be executed then the other mode. I think I will only implement the choice of the mode at the beginning of the program, not during the program, cos of initializating statements...I hv added more info to the qn, pls check it out.
  • @yeeen: Reread the links about the State pattern. It will still cover what you want in a nice, clean way.