Within programs we very often want to execute a different section of code, depending upon various conditions within C the If statement is used to achieve this. The If statement consists of two parts namely

  if (relational expression)
    {
      operation;
      operation;
    }
  else 
    {
      operation;
      operation;
    }
 
The relational expression of the statement   is a logical expression i.e. A== 50, the expression is true if A indeed contains the integer 50. Other logical expressions are valid i.e. 

    == Equals
    > greater than
    < less than
    >= greater than or equal to
    <= less than or equal to
    != not equal to
 
e.g.
  if ( x== 3.142)
    {
      printf("I have found pi\n\r");
    }