C Language Updates

C is an procedure oriented programming language. For any begginer the word program is new.

Program: Set of instructions to be followed by machine or computer.

Instruction Examples: Arithmetic instruction like 

a=b+c;

 Semi colon here indicates end of instruction.

Collecting different variety of instructions into one name and executing it on machine. That one common name is noting but a procedure, function or method.

A C program can have n number of methods.

First sample program:

#include 
int main()
{
   // printf() displays the string inside quotation
   printf("Hello, World!");//printf is a predefined library function
   return 0;
}

First Line of program includes the header file . #include  is a preprocessor command. This command tells compiler to include the contents of stdio.h (standard input and output) file in the program.
Header files in C contaions predefined function definitions. Example: printf(); 

main(): Function that starts the execution of program.

int: here it is return type of main()
A function can return any type of value.Here main is returning int so last line of program 
contains return statment having default int value 0. 

 After compiling  this program we get the filename.obj file. Linker performs linking and at the end we get filename.exe. This exe file is an executable file which is finally executed.

What is printf and from where it comes from in C code.? 

You must have used printf so many times in your Car programs but do you really know everything about printf? Let's see. 

What is the full form of printf? 

Printf function name is made of two words 'Print format'. Here format means format specifiers like%d %f etc. 

Printf and scanf functions are actually included in your code by line #include header file. This file contents only header of standard IO functions and respective stdio.c file contains function definitions. 

How to print Hex, Oct and Decimal number formats? 

printf("%x", 10) ; this will print small 'a' on screen which is hex value of number 10.

printf("%X", 10) ; this will print capital A' on screen. 

printf("%#x", 10) ; this will print small '0xa' with prefix 0x on screen. 

printf("%o", 10) ; this will print '12' on screen which is octal value of number 10 

printf("%5d", 10) ; this will print 3 spaces and then number 10 on screen because right alignment given in format i.e. "%5d".

For left alignment use "%-5d" Negative number it will print 10 and then 3 spaces. 

What if you want a variable number of spaces instead of a constant number in format specifiers then use the star as below. 

int s = 5;

printf("%*d",  s, 10); this will give s number of spaces before printing number 10.

%g - is used to print float number without trialling zero. For example. 

printf("%g", 10.2); this will print only 10.2 and not like%f prints 10.200000 always 6 trialling zeros. 

 %p - is used to print pointer values. That means addresses which are hex values. 

%u - is used to print unsigned numbers that means positive numbers. 

%i and %d are equivalent. 

%c - is for character and%s is for word. 

There are also many escape sequence characters which are commonly used but not known to all are:

To print% sign use double%% to avoid conflict with format specifiers and the actual per cent sign. 

Example

printf("i got %d%% in practicals\n", 100) ; this will print I got 100% in practicals

Similarly, to print double quotes use \" . 

Example 

printf("I love \"C\" Language\n", 100) ; this will print I love "C" Language. 

To print backslash use double backslash \\

To bring back cursor to start of the line use \r and to backspace or delete previously printed char on-screen use \b.

Using above \r and \b we can really create loading or progress bar effect on screen because we can display on same line different text with time delay. 

for(I = 0; I <= 100; I ++) 

{

     printf("loading.... %d\r") ;

     // some delay... 

}

This will print loading..... 0 till 100 on same line. 

There are so many such things you must explore to know what printf can do, isn't it? 

Lower order and higher-order bytes are the terms used while computing calculations in a programming language. Usually, numbers are written from left to right. The left is the most significant bit, and it is written first. 

For example, if we consider your paycheck, then you would be happier if the number the first digit increases instead of the last digit. This is what is referred to as "significance" of a digit. 

The bits present in computer memory are written usually with a base 2 (for binary, the base is considered as 2). So, the least significant bit is represented as one. The next bit is represented as two or 2'1 and the next one as 2'2'1 and so on..

For example, if we consider 2 bytes of memory, which represents a 16-bit number, then one byte will hold at least eight significant bits, and the other byte will hold the most significant 8 bits. 

The byte that contains the most significant 8 bits is called the higher-order byte and the one that contains the least significant bits is called the higher-order byte. 

The header file which is added to the program that one has written is basically what 'include stdio.h.' means. Stdio.h is known to contain the input and output operations like "printf" or "scanf" etc. "h" extension means the header file.

If you request to use a header file in the program by actually including it with the preprocessed C directive #include like you have seen the inclusion of stdio.h header file, which comes along with the compiler you are using.

If the header file is equal to that of copying the header file, it is advised not to do it because it would be inevitable to get an error and it's, of course, a bad idea to copy the content of the header file into its designated source files, as in if at all one has multiple source files in a written program.

In layman's terms, It's effortless .#include is what is known as a "preprocessor". As the name suggests, it is preprocessed before the code. These preprocessor statements are compiled before any other code in your script.
Hope this helps