Q.Explain the basic structure of a C program. The textbook views a C program as a group of building blocks called functions and presents the general structure as follows:

Documentation Section  
Link Section  
Definition Section  
Global Declaration Section  
main() Function Section  
{  
    Declaration part  
    Executable part  
}  
Sub program Section  
    Function 1  
    Function 2  
    -    -  
    -    -    (user defined functions)  
    -    -  
    Function n  

A C program is organised as an ordered set of sections that begins with optional documentation and preprocessor directives and always contains exactly one main() function, where execution starts.

[!ANSWER]

The structure is: Documentation Section, Link Section, Definition Section and Global Declaration Section, then the compulsory main() function (holding a declaration part and an executable part), and finally an optional Sub-program Section of user-defined functions.

[!TLDR]

Every C program follows a fixed skeleton whose only compulsory part is the main() function; all other sections are optional but always appear in the same order.

A C program is built from functions, and to write a program we first create the functions and then put them together. The sections of the program, in order, are:

• Documentation Section: comment lines (giving the program name, author, purpose, date) that improve readability and are ignored by the compiler.
• Link Section: the preprocessor #include directives that link the program with header/library files such as stdio.h.
• Definition Section: the #define directives that define symbolic constants and macros.
• Global Declaration Section: declarations of variables and functions that must be available throughout the program (before main()).
• main() Function Section: the compulsory function where execution begins. Its body, enclosed in braces { and }, has two parts — a declaration part (declaring the variables used) and an executable part (the statements that perform the task).
• Sub-program Section: the user-defined functions (Function 1, Function 2 ... Function n) that are called from main() or from one another.

Only the main() function is mandatory; a valid program can contain just main(). The other sections are added as the program needs them. This layout is a standard Karnataka 2nd PUC Electronics C-programming question.

[!ANSWER]

A C program consists of the Documentation, Link, Definition and Global Declaration sections, followed by the mandatory main() function (with its declaration and executable parts) and an optional Sub-program section of user-defined functions; execution always starts at main().