You have seen a basic structure of C program, so it will be
easy to understand other basic building blocks of the C programming language.
Tokens in C
A C program consists of various tokens and a token is either
a keyword, an identifier, a constant, a string literal, or a symbol. For
example, the following C statement consists of five tokens:
printf("Hello, World! \n");
The individual tokens are:
printf
(
"Hello, World! \n"
)
;
Semicolons ;
In C program, the semicolon is a statement terminator. That
is, each individual statement must be ended with a semicolon. It indicates the
end of one logical entity.
For example, following are two different statements:
printf("Hello, World! \n");
return 0;
Comments
Comments are like helping text in your C program and they
are ignored by the compiler. They start with /* and terminates with the
characters */ as shown below:
/* my first program in C */
You cannot have comments within comments and they do not
occur within a string or character literals.
Identifiers
A C identifier is a name used to identify a variable,
function, or any other user-defined item. An identifier starts with a letter A
to Z or a to z or an underscore _ followed by zero or more letters,
underscores, and digits (0 to 9).
C does not allow punctuation characters such as @, $, and %
within identifiers. C is a case sensitive programming language. Thus, Manpower and manpower are two different identifiers in C
Keywords
The following list shows the reserved words in C. These
reserved words may not be used as constant or variable or any other identifier
names.
auto
|
else
|
long
|
switch
|
break
|
enum
|
register
|
typedef
|
case
|
extern
|
return
|
union
|
char
|
float
|
short
|
unsigned
|
const
|
for
|
signed
|
void
|
continue
|
goto
|
sizeof
|
volatile
|
default
|
if
|
static
|
while
|
do
|
int
|
struct
|
_Packed
|
double
|
Whitespace in C
A line containing only whitespace, possibly with a comment,
is known as a blank line, and a C compiler totally ignores it.
Whitespace is the term used in C to describe blanks, tabs,
newline characters and comments. Whitespace separates one part of a statement
from another and enables the compiler to identify where one element in a
statement, such as int, ends and the next element begins. Therefore, in the
following statement:
int age;
There must be at least one whitespace character (usually a
space) between int and age for the compiler to be able to distinguish them. On
the other hand, in the following statement:
fruit = apples + oranges; // get the total fruit
No whitespace characters are necessary between fruit and =,
or between = and apples, although you are free to include some if you wish for
readability purpose.
|Footer Menu |
| Introduction | Basic Syntax | Data Types | Variables | Arrays | Constants and Literals |
| Decision Making | Functions | L values and R values | Loops | Nested if statements | Nested loops |
| Nested Switch Statements | Operators | Pointers | Scope Rules |
| Strings | Storage Classes | Structures | Switch Statement |
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