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Introduction To C Programming : Dennis Ritchie and Ken Thompson

What is C :

What is C :

  • The c programming language is a standardized programming language that was developed by Dennis Ritchie and Ken Thompson in the early 1970s at bells lab.
  • It is one of the Best and most widely used programming languages
  • It was designed to provide access to the low-level maps and to require less runtime support.

Steps involved in C languages :

Alphabets , digits , special symbols >>> constants, variables ,  keywords >>> instructions >>>  program

The C character set:

Alphabets  -  A ,B,....X,Y,Z
                       a,b,c.....y,z.
Digits -  0,1,2,3,4,5,6,7,8,9
Special symbols -  !, @ ,# ,%, ().../?$

Constants variables and keywords :

  • A constant is an entity that does not change it is also called literals.
  • A variable is an entity that may change and also called identifiers.
  • A keyword is a special word In this language that carries special meaning.

Types of c constants:

  Now C constants can be easily divided into two major categories : 

  ( A) Primary constants :
                                      An integer constant, Real constant, Character
  (B) Secondary constants :
                                     Array, Pointer, Structure, Union, Enum



C keywords:

  • There are only 32 keywords a label in C.
  • The keywords cannot be used as variable names.
  
There are only 32 keywords a label in C.

Begin with the first C program -
1. #include<stdio.h>
2. int main (void)
3. {
4. printf("hints4you");
5. return 0;
6. }

Line 1: #include<stdio.h>
Preprocessor
                              The C preprocessor is a macro preprocessor that transforms the program before it is compiled. 

There are few of the common uses of C preprocessor are :
  • Include header files
  • Macros
  • Conditional compilation
Header file : 
 
The header file is a file which contains a function declaration and macro definition which is to be shared between various source file. 

It has two types:
  • The files which the programmer writes.
  • The files which come with the compiler. 
Name                                 Description
<complex.h> :  A set of functions in this language for manipulating complex numbers 

<stype.h>  : Define the state of functions used to classify characters by their types or to convert between upper and lowercase in a way that is independent of the used character set. 

<errno.h> : For testing error codes in this language reported by library functions. 

<float.h> : Define macro constants find the implementation-specific properties of the floating-point library. 

<stdnoreturn.h> : For specifying non returning function .

<string.h>: Define string handling functions .

<tgmath.h>: Define type generic mathematical functions .

<threads.h>: Define functions for managing multiple Threads as well as mutexes and condition variables. 


<time.h> : Define date and time handling functions .

<uchar.h>: Types and functions for manipulating Unicode characters. 

<wctype.h>: Define the state of functions used to classify white characters by their types or to convert between upper and lowercase. 

Line 2: int main(void )
  • It is the starting point from where the execution of the C program begins.
  • The execution begins with the main ()function.
Line 3 and 6: {}
  • Used to define a scope or function and control statements always start and ends with curly brackets.
Line 4: print("hints4you");
  • The printer is a predefined standard library function to print the given string i.e. "hints4you" on standard output.
Line 5: return 0;
  • The return statement returns the value from main () and 0 indicates the successful termination.

Data types:

  • In the case of  C programming language data types are seriously declarations for memory locations or variables.
  • The C language provides the four basic arithmetic type specifiers char, int, float, double.
  • The modifiers signed, unsigned, short and long. 
The C language provides the four basic arithmetic type specifiers char, int, float, double.





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