What are the four steps to convert a C program into machine code?

The process of creating and running a program

• A program consists of a set of instructions written in a programming language.

• A programmer’s job is to write and test programs.

• The 4 steps to convert a 'C' program into machine language are:

  • Writing and Editing the Program
  • Compiling the Program
  • Link program
  • Execute program

Write and edit program

• Write using a text editor program.

• With a text editor, users can enter, change, and store character data.

• All special text editors are usually included with the compiler.

• After writing the program, save the file to disk.

• It is called the "source file".

• This file is the input to the compiler.

Compiler

• "Compiler" is a program that converts source programs into machine language software.

• The "C" compiler is divided into two separate programs.

  • Preprocessor
  • Translator

Let’s look at the preprocessor first-

Preprocessor

• The preprocessor reads the source code and then prepares it for the translator.

• Preprocessor commands start with the "#" symbol.

• They tell the preprocessor to find a special code base and replace it.

• The result of preprocessing is called "translation unit".

Translator

• The job of a translator is to convert a program into machine language.

• It reads translation units and generates "object modules".

• But it is not a fully executable file because it does not contain "C" and other functions.

Linker

• The "linker" assembles the I/O functions, some library functions and functions in the source program into the final execute program.

Execute the program

• The "loader" is the software that prepares the program for execution into memory.

• During execution, the program reads data from the user, processes the data and prepares output.

Example 1

The following example is to find the average of 3 numbers-

Real-time demonstration

#include<stdio.h>
int main(){
   int a,b,c,d; //declaring 4 variables
   float e;
   printf("Enter values of a,b,c:");
   scanf("%d,%d,%d",&a,&b,&c); //read 3 input values from keyboard
   d=a+b+c;
   e=d/3;
   printf("Average=%f",e); // printing the result
   return 0;
}

Output

Enter values of a,b,c :2,4,5
Average=3.000000

Example 2

The following is the calculation of the circumference of a circle-

Real-time demonstration

#include <stdio.h>
#define PI 3.1415 // defining PI value
main (){
   float c,r;
   printf("Enter radius of circle r=");
   scanf("%f",&r);
   c=2*PI*r;
   printf("Circumference of circle c=%f", c);
}

Output

Enter radius of circle r=5.6
Circumference of circle c=35.184799

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