variables and data types in C
variables
a variable is an entity that has a value and is known to the program by a name. a variable define Associates a memory location with the variable name. a variable can have only one value assigned to eat at any given time during the execution of program . its value may change during the execution of the program.
example
a=20.5;b=10;
here, A and B are variables.
variable names are identifier used to name variables. they are symbolic names given to memory location. A variable name consists sequence of a of letters and digits, the first character being a letter. the rules that apply to identify also apply to variable names.
example of valid variable name are:
a. abcl. stu-data
class. employee. 12MAX
examples of invalid variables names are:
a's- illegal character(')
Stu data- blank space are not allowed
2MAX- first character should be a letter
Class,mark- comma not allowed
basic data type :
the C language support the following basic data types:char - a single bird that can hold one character
int - an integer (non-decimal number) (2 bytes space)
float - a number with decimal value ( 4 bytes)
double - number with decimal value (8 bytes)
qualifiers:
a qualifiers alters the characteristics of the data types, such as its size or sign. in c u can apply qualifiers to above data type to get additional data types. the qualifiers that alter the size are 'short' and 'long'.short int - integer represented by a laser number of bits (usually 16)
long int - integer represented by a greater number of bits (usually 32)
long double - an extended decimal number.
the expect size of these data types depends on the compiler.
the sign qualifiers are "signed" and "unsigned"
- signed int
- signed long int
- unsigned short int
- unsigned int
- unsigned long int
- signed char
- unsigned char
normally qualified (short and long) cannot be applied to the data types 4 and plot and sign qualified (signed and unsigned) cannot be applied to float, double and long double.
operator function
operator function
operation("?") and(":")
Syntax= expression=exp1?exp2:exp3;
Example:
a=50
b=a>100?25:35 ;
hear the value of will be 35 because is less than 100 and condition is false.
operators in C
operator are symbols that act upon data. they represent a particular operation to do performed on the data. operators can be kal classified in the following categories:* arithmetic operators:
The arithmetic operator performs arithmetic operation on any built in data types.- operator. function
- + addition
- - subtraction
- × multiplication
- / exponentiation
- % modulus (remainder)
* special arithmetic operators
- ++ increment
- - - decrement
X++ OR ++X is equivalent to X=X+1
similarly
X-- OR --X is equivalent to X=X-1
relational operators these operators are used to compare two values on the basis of a certain condition.
*OPERATORS. FUNCTION
- < less than
- <= less than equal
- > greater than
- >= greater than equal
- != not equal to
- == equal to
logic operators:
these operators are used to perform logical operations.operator function
- && and
- || OR
- ! NOT
assigning operators:
this operator are used to assign value to variables.operator function
- = assign a value
- += add the value and assign it to the left
- -= subtract the value and assign it to the left
- *= multiply the value and assign it to the left
- /= divide the value and assign it to the left
- %= find the remainder and assign it to the left
ternary operators:
these operators are very powerful operator in C. in some cases it is equivalent to the "if"- else statement.operation("?") and(":")
Syntax= expression=exp1?exp2:exp3;
Example:
a=50
b=a>100?25:35 ;
hear the value of will be 35 because is less than 100 and condition is false.
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