In the c programming language, a macro would generally look like. For example in the following program max is defined as 100. The result is that the arguments are scanned twice to expand macro calls. What is the advantages of macro over a function in c answers. Other nonstandard predefined macros describe the kind of cpu, with more. Once youve defined a macro, you cant redefine it to a different value without first removing the original definition.
A generalpurpose macro processor or general purpose preprocessor is a macro processor that is not tied to or integrated with a particular language or piece of software a macro processor is a program that copies a stream of text from one place to another, making a systematic set. Somehow i had the idea the merging took place during compilation. Often the difference between the two is also asked in c interviews. Arnold schwarzenegger this speech broke the internet and most inspiring speech it changed my life. Aug 11, 2015 here is implementation of macro processor in c. A macro is actually a miniature but complete computer program often generated with an application program such as a word processor that carries out a sequence of operations intended by the user or programmer. You request the use of a header file in your program with the c. A user turns on the recorder, calls up a menu, selects a variety of options, turns the recorder off and assigns a key. Since it can record both mouse actions and keyboard input for play back, we consider it to be a macro software.
A macro is a segment of code which is replaced by the value of macro. About command macros autocad lt 2019 autodesk knowledge. As an example, i modified the code used in example of the last section in this way. The c preprocessor offers the following operators to help create macros. Reading csvexcel files, sorting, filtering, groupby duration. Top 10 free macro automation software for computers to. One strange phenomenon when coding in c is usin g macr os. Macros are generally used to define constant values that are being used. By design, c provides constructs that map efficiently to typical machine instructions and has found lasting use in applications previously coded in assembly language. C is a highlevel and generalpurpose programming language that is ideal for developing firmware or portable applications. Expanded program macro processor a program with macro definitions and macro invocations a program without macro definitions assembler object program 4. Macro substitution is done by the c preprocessor, and basically replaces all occu. For more on the compilation process, please refer to the article.
Dear readers, these c programming interview questions have been designed specially to get you acquainted with the nature of questions you may encounter during your interview for the subject of c programming. Macros can be created with the word macro recorder, which stores repetitive keystrokes. Till now you might have got some idea about the acronym, abbreviation or meaning of macro. As per my experience good interviewers hardly plan to ask any particular question during your interview, normally questions start with. For those with computers set to use the english language, programs have traditionally been installed in the program files folder of the c. In this tutorial we intend to cover the basics of these two concepts along with working code samples. If the macro s definition is a function with one or more arguments, then the function. The c preprocessor is a macro processor that is used automatically by the c compiler to transform your program before actual compilation. Basic macro processor functions macro definition two new assembler directives macro mend a pattern or prototype for the macro instructiona pattern or prototype for the macro. In 1963, timothy hart proposed adding macros to lisp 1. The preprocessor examines the code before actual compilation of code begins and resolves all these directives before any code is actually generated by regular statements.
Ranked among the most widely used languages, c has a. How to use c macros and c inline functions with c code. C macros with programming examples for beginners and professionals covering concepts, control statements, objectlike macros, functionlike macros, c predefined macros, c predefined macros example, c array, c pointers, c structures, c union, c strings and more. C programmingpreprocessor directives and macros wikibooks. Using macros can be extremely unsafe and they hide a lot of pitfalls which a re v ery hard to find. A macro is a name given to a block of the code which can be substituted where. The c preprocessor is a macro preprocessor allows you to define macros that transforms your program before it is compiled. Xmacros are based on the property of nested macros and the ability to define macros inside other macros. Gcc preprocessor doesnt really care that input is a c program. It can be as simple as a command such as circle and include special characters such as cc. You can also use macros to enter words or phrases that you use frequently. In the mid1950s, when assembly language programming was commonly used to write programs for digital computers, the use of macro instructions was initiated for two main purposes. As a simple example, in the c programming language, this is a typical macro that is not a parameterized macro. It expands macros in parts of some directives that arent skipped as part of a conditional compilation.
In computer programmi n g, macr os are a tool that allows a developer to reuse code. A macro defines the action that should be performed when a user interface element is used. When the code above is run, we see the following output. Programs cannot define new preprocessing directives. Rdbuff a onepass macro processor th tthat can alternate between macro definition and macro expansions able to handle macros. Macro definition, very large in scale, scope, or capability. How to use c macros and c inline functions with c code examples. In more technical terms, a computer virus is a type of malicious code or program written to alter the way a computer operates and is designed to spread from one computer to another. A stored macro can then be accessed from a menu list or from the toolbar and run by simply clicking. Group of several keystrokes or computer instructions assigned to one or more keystrokes or mouse clicks, or embedded in a program. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs.
After substitution, the entire macro body, including the substituted arguments, is scanned again for macros to be expanded. A macro is a name given to a block of c statements as a preprocessor directive. Macro has two computerrelated definitions, both of which involve making your computer experience more efficient. Macro programming synonyms, macro programming pronunciation, macro programming translation, english dictionary definition of macro programming. A macr o is a name given to a block of c statements as a preprocessor directive. Here you will need to provide assembly program containing macro as input in macin. May 29, 2012 so in the code above, a value of 25 is given to the macro macro1. Jan 01, 2018 macro, example program for macro in assembly language in urdu hindi macro in assembly in hindi, example of macro in assembly language in hindi, assembly language macro, difference between macro. Being a preprocessor, the block of code is communicated to the compiler before entering into the actual coding main function. A macro short for macroinstruction, from greek long in computer science is a rule or pattern that specifies how a certain input sequence often a sequence of characters should be mapped to a replacement output sequence also often a sequence of characters according to a defined procedure. An excel macro is typically created by recording a sequence of keyboard and mouse actions using the macro recorder. As per my experience good interviewers hardly plan.
This sample macro, available for both macro express and macro express pro, demonstrates how to get the program files folder that is used for 32 bit applications. Whenever the name is used, it is replaced by the contents of the macro. The c preprocessor is a useful tool that allows programmers to work around the limitations of c. In graphical user interfaces, to close a window means to exit an application or file. They differ mostly in what they look like when they are used. Macro dollar is an old and simple automation software that was originally created around 10 years ago for paid to surf programs to click on advertisement bars installed on computers. Macro arguments are completely macroexpanded before they are substituted into a macro body, unless they are stringified or pasted with other tokens. And dealing with them is inevitable in c programming. The macro continuation operator \ is used to continue a macro that is too long for a single line. Interesting facts about macros and preprocessors in c. You may define any valid identifier as a macro, even if it is a c keyword.
A generalpurpose macro processor or general purpose preprocessor is a macro processor that is not tied to or integrated with a particular language or piece of software a macro processor is a program that copies a stream of text from one place to another, making a systematic set of replacements as it does so. If the macros definition is a function with one or more arguments, then the function. These transformations can be the inclusion of header file, macro expansions etc. This happens before the macro definition is even parsed. Originally intended for writing system software, c was developed at bell labs by dennis ritchie for the unix operating system in the early 1970s. A program routine that converts menu selections and keystrokes into a macro. You can also define macros whose use looks like a function call.
These transformations are lexical, meaning that the output of the preprocessor is still. Macros enable you to assign short names to source code blocks. Objectlike macros resemble data objects when used, functionlike macros resemble function calls. In graphical user interfaces, to close a window means to exit an application or file, thereby removing the window from the screen. The meaning of the macro is also explained earlier. In computer programming, macros are a tool that allows a developer to reuse code. Macros in c programming dont consider it as an outdated. Preprocessors are a way of making text processing with your c program. Thus, the same definition may appear more than once in a program. What difference is there in the macro security settings\trusted location settings between the computers on which the macros work and on those on which they dont. Macros are created either in documents or templates. This definition of macro is reflected inside the code and accordingly the code is compiled. Macro programming definition of macro programming by.
On compilation of the program, the a and b in the macro definition will be replaced by 10 and 20 respectively. It can also be created using visual basic because even a recorded macro is made up of visual basic code. A macro short for macroinstruction, from greek long in computer science is a rule or. A header file is a file containing c declarations and macro definitions.
The mapping process that instantiates transforms a macro use into a specific. The definition of macro is given above so check it out related information. For instance, in the c programming language, this is an example of a simple macro definition which incorporates arguments. It can be as simple as a command such as circle and include special characters such as c c. A macro is a name given to a block of the code which can be substituted where the code snippet is to be used for more than once. Macro processor algorithm andmacro processor algorithm and data structuresdata structures submacro definitions are only processed when an invocation of their supermacros are expanded see figure 4. A script that is executed within a microsoft word document that adds some automatic function for the user. Lets discuss different types of macros and predefined macros. However, you can redefine the macro with exactly the same definition.
It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs the c preprocessor provides four separate facilities that you can use as you see fit. It is called a macro processor because it allows you to define macros, which are. Often the difference between the two is also asked in c interviews in this tutorial we intend to cover the basics of these two concepts along with working code samples. You change one character in a macro definition and the whole code for all the messages may become totally different. A virus operates by inserting or attaching itself to a legitimate program or document that supports macros in order to execute its code. These lines are not program statements but directives for the preprocessor. The components that define this macro are explained in the following table. Now you can enter the name of the macro, and the word processor will perform all these commands at once. The c preprocessor modifies a source code file before handing it over to the compiler. Other nonstandard predefined macros describe the kind of cpu, with more or less specificity. When you use the macro name in your source file, the preprocessor replaces it with the source code block specified in the macro definition. The reason is, the preprocessor will replace all the macros in the program by its real definition prior to the compilation process of the program. For example, you could define a macro to contain all the keystrokes necessary to begin a letter your name, address, and a code that inserts the current date.
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