1.15 Executing a ' C ' Program.

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 Executing a ' C ' Program.

Executing a program written in C involves a series of steps. These are:

  1. Creating the C program.
  2. Compiling the C program.
  3. Linking the C program.
  4. Executing the C program.


1) Creating the C program: -

  • An editor like notepad, WordPad, or Editplus etc. are used to create or write a c program.
  • The code which we have written inside the editor is known as source code and should saved with “.c” extension.


2) Compiling the C program: -

  • After writing the source code in editor, which is ready for compilation process.
  • The source code is compiled by the compilers.
  • The compiler converts C source high level code to low level code as assembly source code.
  • Then assembler is ready to convert assembly source code to binary code, which code was well understandable by computer machine. i.e. object code.

 

3) Linking the C program: -

  • In this step, the object code of a C program is linked with libraries that are needed for execution of a program.
  • The linker is a program which is used to link the program with needed libraries.
  • It creates an executable file with “.exe” extension.


4) Executing the C program: -

  • Finally, the executable file is run by DOS command prompt or by any other related software.




Process involved in program execution, compilation, interpretation, loading, linking.

In C programming, the execution of a program involves several important steps:

  • writing, compiling, linking, loading, and execution.
  • These steps convert human-readable source code into machine-executable instructions.



1) Writing the Program (Source Code Creation): -

  • The programmer writes the C code using a text editor and saves it with a .c extension. 
  • This file is called the source file, which contains instructions in a high-level language that humans can understand.

 

2) Compilation: -

  • The compiler translates the source code into object code, which is a low-level machine-readable form.
  • During this step, syntax errors are checked and reported.
  • It creates an object file with a .o or .obj extension.

 

3) Linking: -

  • The linker combines the object file with required libraries (like standard input/output functions).
  • If you used printf( ) in your code, the linker ensures that the final executable includes the correct machine code for that function.
  • The linker outputs a complete executable file (e.g., program.exe on Windows).

 

4) Loading: -

  • The loader is a program, which is part of the operating system, that loads the executable file into main memory (RAM) before execution.
  • It allocates memory for the program's instructions and data, sets up the stack, and prepares the CPU to run the program.


5) Execution: -

  • The processor executes the machine code instructions from memory.
  • It follows the main( ) function and performs all logic and operations defined in the code.


6) Interpretation: -

  • C is a compiled language, not an interpreted one.
  • Compilation: Converts the entire program to machine code before execution.
  • Interpretation: Executes code line-by-line, translating at runtime (used in languages like Python).
  • C programs are not interpreted.







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