IN CASE - UNLESS

IN CASE,  IN CASE OF,  UNLESS : how and when to use them.

• IN CASE
  
  In case expresses the possibility of something happening.
  It is used to express the idea of doing something to avoid a possible problem later on.
  It gives the reason for an action.
  
  
  • Take an umbrella in case it rains.
    = There is a possibility that it will rain, so it's a good idea to take an umbrella.
    
    
  • You'd better take a coat in case it gets cold later on.
    = It could get cold later on, so it might be safer to take a coat.
    
    
• IN CASE + 'of'
  
  In case of means 'if there is' or 'if (something) should happen'.
  
  
  • In case of emergency, call this number.
    = If there is an emergency, call this number.
    
    
  • In case of breakdown, please press the red button to call for assistance.
    = If the lift breaks down, please press the red button.
    
    
• UNLESS
  
  Unless means 'except if' or 'only if'.
  Unless replaces 'if' + a negative verb.
  
  
  • Sally won't come unless you invite Harry.
    Meaning:
    • Sally won't come except if you invite Harry.
    • Sally will only come if you invite Harry.
    • If you don't invite Harry, Sally won't come.
      
      
  • We will have a picnic unless it rains.
    Meaning:
    • We will have a picnic except if it rains.
    • If it doesn't rain we will have a picnic.
    • If it rains, we won't have a picnic.