Cast Operator / type casting

Cast Operator / type casting

• Type casting is a way to convert a variable from one data type to another data type.
• Type casting can be achieved by using cast operator.
• It will convert variable or expressions value according to specified datatype.

  #include<stdio.h>
  main()
  {
    int a=3,b=2;
    float c;
    c=(float)a/b;
    printf("Result is %f",c);
  }

Result is 1.500000 
  

sizeof operator

• It is used to find memory size of variable or datatype.
• sizeof operator will return the size in integer format.
• The operand may be an expression/variable or it may be a datatype.

  #include<stdio.h>
  main()
  {
    int a=100;
    char b='a';
    printf("size of int %d",sizeof(a));
    printf("size of char %d",sizeof(b));
    printf("size of float %d",sizeof(float));
  }

size of int 2 or 4
size of char 1
size of float 4
  

Symbolic Constants

• A symbolic constant is a constant value which have some name .
• const keyword By using this keyword a constant can be define by using syntax.

  #include<stdio.h>
  const float pi=3.14;
  main()
  {
    int r;
    float a,c;
    printf("Enter Radius ");
    scanf("%d",&r);
    a=pi*r*r;
    c=2*pi*r;
    printf("Area is %f",a);
    printf("\nCircumference is %f",c);
  }

Enter Radius 5
Area is 78.500000
Circumference is 31.400002
  

enums

• Enumeration (or enum) is a user defined data type .
• It is mainly used to define series of integral constants.
• The enums make a program easy to read and maintain.
• For ex: enum week{ Mon, Tue, Wed, Thur, Fri, Sat, Sun } ;
• By default, const1 is 0, const2 is 1 and so on.
• You can change default values of enum elements during declaration (if necessary).
• For ex: enum days { FRI, SAT = 10, SUN };

• enum week{ Mon, Tue, Wed, Thur, Fri, Sat, Sun } ;  

    main()
    {
        printf("%d",Wed);
    } 

    Output : 2
    

• enum days { FRI, SAT = 10, SUN };

    main()
    {
        enum days day;
        day = SUN;
        printf("%d", day ) ;
    } 

    Output : 11
    

C program compilation process

• Source Code File
• This file contains our program.
• File extension is .c
• Preprocessing
• It processes all preprocessor commands such as #include, #define etc.
• File extension is .i
• Compilation
• The compiler converts preprocessed file into assembly code.
• File extension is .s
• Assemble
• The Assembler converts compiled assembly code into object code ( machine code).
• File extension is .obj or .o
• Linking
• The Linker links library functions object code with our programs object code.
• File extension is .exe

#define preprocessor

  #include<stdio.h>
  #define pi 3.14
  main()
  {
    int r;
    float a,c;
    printf("Enter Radius ");
    scanf("%d",&r);
    a=pi*r*r;
    c=2*pi*r;
    printf("Area is %f",a);
    printf("Circumference is %f",c);
  }

Enter Radius 2
Area is 12.560000
Circumference is 12.560000