Program Forms
A program consists of one or more functions. One must be
named main(), and execution starts with it. The statements of a function are
enclosed between opening and closing braces:
Main() /*
function name*/
int m; /*
declaration statement */
for ( m = 1; m
< 5; m++)
printf(“%d
%d\n”, m, m + 1);
Programs may include preprocessor directives and more than
one function. Function definitions follow one another. Do not embed one
function definition within another function.
Execution starts at main() regardless of the function order. Functions
should declared, or prototyped, before they are used.
#define RANGE 15 /* preprocessor definition */
int odd(int);
/* ANSI prototype for odd() */
void main (void)
/* specify type, arguments */
{
int n;
for (n=1;
n< RANGE; n++)
printf(“%d
%d\n”, n, odd(n));
} /* end of
main() function */
int odd(int k)
/*odd() has int arg and an */
{
int j; /* declare local variables */
j=2*k+1;
return j;
} /* end of odd()
function */
In a function with arguments, the arguments are declared
before the body of the function, as marked by the opening brace, and local
variables are declared after the brace.
Statements
Simple Statements consists of an expression or
instruction followed by a semicolon:
float x; /*
declaration statement */
x=1.14; /*
assignment statement */
printf(“Friends!”); /* function call statement */
Structured Statements consist of a keyword followed
with a test statement within parentheses followed by simple statement.
If (variable == 12345)
y=m*x+b;
A compound statement, or block, consists of one or
more statements enclosed in braces. It counts as one statement and is used in
structured statements to allow the inclusion of more than one action in the
statement:
If (idnumber == 10007)
{
salary =
salary + bonus;
status++;
}
Variable Types
Simple variables come in two basic varieties: integer and
floating point.
Integer types
char
signed char
unsigned char
short
int
long
unsigned, unsigned int
unsigned short
unsigned long
Floating types
float
double
long double
Storage Classes
Declaring Variables
Simple Statements consists of an expression or
instruction followed by a semicolon:
float x; /*
declaration statement */
x=1.14; /*
assignment statement */
printf(“Friends!”); /* function call statement */h
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