Constants in C: Constants are the terms that can't be changed during the execution of a program.
Examples: Integer Constants: 0, 1, 2, 3, 4, 5, 6, 7 . . . . . . .
Floating Constants: 0.0, 0.1, 0.2, 0.3, -0.4, 0.5, 5.1546, 2.5465, -1.02545 . . . . . . .
Character Constants: Character constants are the constant which use single quotation around
characters. For example: 'a', 'l', 'm', 'F' etc.
Variables in C: Variables are memory location in computer's memory to store data. To indicate the memory location, each variable should be given a unique name called identifier. Variable names are just the symbolic representation of a memory location. Examples of variable name: ABC, var_no, var_123, Var123, Count etc.
Basic Data Types in C:
Char: a single byte that can hold a character (‘a’, ’b’, ’c’, ’d’, ’e’ . . . . . . . )
Int: An Integer can hold 2 or 4 byte integers (0, 1, 2, 3, 4, 5, 6, 7 . . . . . . .)
Float: A float can hold 4 byte floating points (0.0, 0.1,0.2, 0.3, -0.4,0.5,5.1546, 2.5465, -1.02545 . . .)
Double: Double is same as float just the difference is it can hold up to 8 byte (0.0, 0.1, 0.2, 0.3, -0.4,
0.5, 5.1546, 2.5465, -1.02545 . . . . . . .)
Rules for writing variable name in C:
The first letter of a variable should be a letter, Variable name can be made up of both uppercase and lowercase letters, digits and underscore (_) only.Examples:
Declaration of Variable | ||
#include <stdio.h> void main(){ int a1, a2; int a_1; } | #include<stdio.h> void main ( ){ char b_1; double db; } | #include<stdio.h> void main(){ float a_1, b2, b3, b4; char jvh; } |
a1, a2 and a_1 are declared as integer now they can store integers. | b_1 and db are declared as char and do uble respectively now b_1 can store characters(fonts) and db can store fractioned numbers. | Here a_1, b2, b3, b4 can store floating points and jvh can store charac |
Initialization of Variable | ||
#include<stdio.h> void main ( ){ float b1 ; b1 = 2.302; double a; a = 7.202; } | #include<stdio.h> void main ( ){ char b_1 ; b_1 = ‘r’; int a; a = 7; } | #include <stdio.h> void main(){ int a1 = 5; int b1; b1 = 5; } |
B1 and a are declared and initialized. | Here b_1 is stores / initialize r And a store’s 7 .. | a1 is initialized during declaration and b1 firstly initialize then declare on second line. |
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