Common Mistakes in C : Decision Making Errors

Decision making : if-else,else if ladder Errors

Mistake 1 : Assignment Operator & Comparison Operators

1. Assignment Operator (=) is used for assigning value to variable
2. Comparison Operator (==) checks whether LHS and RHS entries are same or not
3. In if statement Use “==” instead of “=”

if(var = 10)
{
   //Statement 1
   //Statement 2
   //Statement 3
   //Statement n
}

instead of write this …..

if(var == 10)
{
   //Statement 1
   //Statement 2
   //Statement 3
   //Statement n
}

Mistake 2 : Use of Semicolon

1. Using Semicolon at the end of if statement
2. Don’t Use Semicolon.

if(var == 10);

Mistake 3 : Else without using if

1. Error Message : Misplaced Else
2. Else must have corresponding if

Statement1 ;
Statement2 ;
..
   else
     {
     Statement 3;
     Statement 4;
     .
     .
     }
}

Mistake 4 : Opening and Closing Braces

1. If multiple Statements within if must be wrapped in Pair of braces.
2. Error Message : Misplaced else
3. Statement1 and statement2 must be wrapped inside if
4. Here only Statement1 is the part of if

Statement1 ;
  if(condition)
Statement1 ;
Statement2 ;
else
{
Statement 3;
Statement 4;
}

Write it as -

if(condition)
     {
     Statement1 ;
     Statement2 ;
     }
   else
     {
     Statement 3;
     Statement 4;
     }