CrazyEngineers
CrazyEngineers

  • 'Pre Processor' - What Is It?

    aarthivg

    aarthivg

    @aarthivg-HH344f
    Updated: Oct 26, 2024
    Views: 2.3K
    compiler does two jobs pre-processor and translator. what does pre processor do
    0
    Replies
Howdy guest!
Dear guest, you must be logged-in to participate on CrazyEngineers. We would love to have you as a member of our community. Consider creating an account or login.
Replies

  • Neeraj Sharma

    Member • Jun 11, 2012

    As far as I know, a program is passed to the pre-processor before it is executed or in other words before its processing begins. The pre-processor is involved in the task of linking the libraries. For example, consider a C program

    #include<stdio.h>
    int main()
    {
    printf("Hi there");
    }

    #include is a pre processor there which helps in including the header file in the program before the execution begins. If the header file is not included then printf will have no meaning in the program as the definition of printf is in stdio.h header file. Same is the case with including string.h for using string handling functions like strlen(), strcat() etc.
    Are you sure? This action cannot be undone.
    Cancel

  • aarthivg

    Member • Jun 11, 2012

    In the book written by Gilberg, It states that preprocessor reads the source code and prepares it for the translator. While preparing, it scans for the special code called preprocessor commands.
    #-Link-Snipped-#, this preprocessor command is what you say as, checking for header files, whether it is included in the program or it helps to include header file.
    Are you sure? This action cannot be undone.
    Cancel

  • lovejeet

    Member • Jun 12, 2012

    the main task of compiler is translation. that is, compiler is a type of translator which translates high level language into machine language. now, according to the gilberg in his book, the 1st phase of compiling is lexical analysis(there are seven such phases). the lexical analysis reads the source code, scans it and arranges it in tokens. so what preprocessor commands are the commands included in the program to include header file and other files or to define macros. correct me if i am wrong.
    Are you sure? This action cannot be undone.
    Cancel

  • aarthivg

    Member • Jun 12, 2012

    lovejeet
    the main task of compiler is translation. that is, compiler is a type of translator which translates high level language into machine language. now, according to the gilberg in his book, the 1st phase of compiling is lexical analysis(there are seven such phases). the lexical analysis reads the source code, scans it and arranges it in tokens. so what preprocessor commands are the commands included in the program to include header file and other files or to define macros. correct me if i am wrong.
    what is lexical analysis,tokens and macros?

    I have just started learning 'c' (only two days old😉 ). So please try to be in simple words😀
    Are you sure? This action cannot be undone.
    Cancel

  • Neeraj Sharma

    Member • Jun 12, 2012

    Lexical analysis divides the code in simple parts like c=a+b can be divided as a combination of tokens where c,=,a,+,b are called tokens or lexemes.

    Macro is another type of pre processor. As #include is used for including files, macro is used to have an alternate definition or kind of substitution .
    #define pre processor is used for defining a macro
    #define PI 3.14
    signifies that wherever you mention PI in your program, it will be replaced by 3.14 at the time of calculation.
    A compiler has following phases:
    Lexical Analysis, Syntax Analysis, Semantics Analysis, Intermediate Code generator, Code Optimizer, Code Generator.
    Are you sure? This action cannot be undone.
    Cancel
Home Channels Search Login Register