Control Structures / Statements In C Language
A program is nothing but the execution of sequence of one or more instructions. 
Quite often, it is desirable to alter the sequence of the statements in the program depending upon certain circumstances. (i.e., we have a number of situations where we may have to change the order of execution of statements based on certain conditions)  
    (Or)  
Repeat a group of statements until certain specified conditions are met. 
This involves a kind of decision making to see whether a particular condition has occurred or not and direct the computer to execute certain statements accordingly.
Based on application, it is necessary / essential

(i) To alter the flow of a program 
(ii) Test the logical conditions 
(iii) Control the flow of execution as per the selection these conditions can be placed in the program using decision-making statements.  

“C” SUPPORTS MAINLY THREE TYPES OF CONTROL STATEMENTS. 

1. Decision making statements
a) Simple if Statement
b) if – else Statement 
c) Nested if-else statement 
d) else – if Ladder 
e) switch statement  

2. Loop control statements
a) for Loop
b) while Loop
c) do-while Loop 
 
3. Unconditional control statements
a) goto Statement 
b) break Statement 
c) continue Statement  
d) return statement