Written by Kousik :
Every programming language has a grammar. Different programming language has different grammar. So to learn C programming language we have to be familiar with that grammar which is related to C program. The grammar is nothing but CONSTANTS, VARIABLES, & their DATA TYPES.
Every programming language has a grammar. Different programming language has different grammar. So to learn C programming language we have to be familiar with that grammar which is related to C program. The grammar is nothing but CONSTANTS, VARIABLES, & their DATA TYPES.
CONSTANTS:
There are two types of C constants. One is PRIMARY and other is SECONDARY.
Primary constants are of three types.
1)
Integer Constant
2)
Real Constant
3)
Character Constant
Secondary constants are of several types.
1)
Array
2)
Pointer
3)
Structure
4)
Union
5)
Enum etc…
Now we have to primary constants first…
Integer Constants:
Characteristics: a) An integer constants must have at least one digit. It must not
have a decimal point.
b)
It can either positive or negative. If no sign proceeds then the integer
assumed to be positive.
c)
The range for integer constants is -2147483648 to +2147483647. The range of
integer constants is depend upon the compiler (visual studio, gcc , turbo c etc).
Example :
400, -421,+755 etc
Real Constants (Floating Point
Constants)
:
Real constants can be shown in two forms.
One is fractional form and other is exponential form.
Characteristics of Fractional form :
a)
A real constants must have at
least one digit . It must have a decimal point.
b)
It can be either positive or
negative. If no sign proceeds then the integer assumed to be positive.
c)
No blanks are allowed within a
real constant.
Example
: -69.35 , 12.00 , +39.355 etc
In exponential form the real is represented
in two major parts . The part coming
before ‘e’ is called ‘mantissa’ and the part coming after ‘e’ called ‘exponent’
.
Characteristics of exponential form:
a)
The word ‘e’ separate the
exponential part and the mantissa part of real constants.
b)
The mantissa part may have +ve
or –ve sign. . If no sign proceeds then the integer assumed to be positive.
c)
The exponent must have at least
one digit.
d)
Range = -3.4e38 to +3.4e38
Example: 3.2e-23, -0.45e+33 etc
Character
Constants:
Characteristics:
a)
A character constant can be a
single alphabet, single digit or a single special symbol enclosed with single
inverted commas.
b)
The maximum length of a
character constant is 1 character.
Example: ‘A’, ‘c’, ‘5’, ‘/’ etc
*Secondary constants will be discussed
later.
VARIABLE:
To store the data value in computer memory
we have to know about VARIABLES.
Variables names are names given to location in memory. These locations
can contain Integer, real, character constants .Type of variables are depending
upon the type of constants. For example an integer type of variable can holds
only the integer constants. The variable name is chosen by the programmer in
such a way that shows its nature in the program.
Example:
class, roll, count etc
Characteristics of variables:
a)
They must begin with a letter.
b)
A variable name is any
combination of 1 to 31 alphabets, digits or underscores. The length of
variables is depending upon the compiler.
c)
No special symbol other than an
underscore can be used in a variable name.
d)
Uppercase and lowercase are
very significant.
C KEYWORDS:
C compiler has some words whose meaning has already been explained.
There are 32 keywords available in C. Different keywords have different
meaning.
auto double int
struct
Break else long switch
case enum register typedef
char extern return
union
const float short unsigned
continue for signed
void
default goto sizeof
volatile
do if static while
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To know more about c keywords you can
follow LET UC C(by yashvant kanetkar) & ANSI C (by Balaguruswamy) .
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