Programming Tutorials

Statements in C

By: Ram in C Tutorials on 2008-07-31  

All the statements in C ends with a ";". The various statements in C are
1)      Declaration Statement
2)      Assignment Statement
3)      Output  Statement
4)      Input Statement
5)      Control Statement
6)      Loop Statement etc.

Declaration Statement:-

It is used to specify the data type of variables used in the program
Syntax:
Datatype Variable or variables separated by , ;
int b;
Here the variable b is int and it allots 2 bytes
int c,e;
Here the variables c and e are int and it allots 4 bytes
float n1,n2;
Here n1, and n2 are declared as float and hence allotted 4 bytes each

Assignment Statement:-

The assignment statement is used to assign a constant to a variable.
Syntax:
Constant;
or
Variable = Variable;
or
Expression;
Eg: (assigned to a constant)
a= 5;
b =10;
Eg: (assigned to a variable)
x=y;
a= 2*e;
Eg: (assigned to a expression)
y= c*d
s= 4*20

Output Statement:

The output statement displays the values and after printing the values it points on the same line.
Syntax:
printf("string format", variable or variables separated by ,);
Here the format means the data specification of the variable. Say, for example
 integer format
------------------
 Decimal %d
 Octal %o
 Hexadecimal %x
float format
--------------
Without exponent %f
With exponent %e
Char %c
printf("Hello World");
The output is Hello World 
printf("%d",x)
The output is the value of x 
printf("sum %d",s)
The output is sum value of s

Input Statement:

The input statement is used to read(accept) constant at the variable at the time of program execution.
Syntax:
scanf("format", & variable or &variables separated by comma,);
scanf("%d",&n);
It asks for the value of n
scanf("%d %d",&a,&b);
run 20
40 (ie.a=20 and b=40) 

Control Statement:

The control statement denotes the sequence of execution of the program. There are two types of control statements namely: conditional control statement and unconditional control statement.
(1)Conditional control statement:
Here, the control is transferred to any part of the program without checking for any condition.
1. --------------
2. goto end
3. -------------
4. end:
5. -------------
goto labelname
The control is transferred to the line where the label starts as shown above.
(2) Unconditional control statement:
Here, the condition is first checked and if it is true then the executes that particular part and if false, then another part is executed.
Eg:  if
     if else
     switch

Loop Statement:

Loop statements are mainly used in programs to do repeated calculations.
Eg: while
    do .while
    for
Syntax:
    while (conditions)
    {
       statements;
    }
Structure of a Program:
Documentation Section
(remarks- comments)
Link section
(to link with other programs)
Global declaration Section
(common declaration)
main()
{
Declaration statement;
Statement part;
}
Sub programs
--------------
---------------
Sample Program:
/* program to find area of a square*/
main()
{
int s,a;
printf("enter the side ");
scanf("%d",&s);
a=s*s
printf("Area of a square= %d",a);
}





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