[ابو بيشو]

Using “if” and “in case”
For sentences where it seems that both can apply, “if” and “in case” can therefore refer to completing actions at different times – “in case” actions are done in advance, while “if” actions only occur on a condition. Consider these examples:
 Call me if you need any help.
 Call me in case you need any help.
The first sentence tells you to call only when you need help, the second sentence tells you to call before you need help (and in this case may be to check whether or not you need help).
 We’ll proofread the report in case there are mistakes.
 We’ll proofread the report if there are mistakes.
The first sentence here says it will be done anyway, to find mistakes, but the “if” sentence tells us there will be no proofreading unless a mistake is found first.
Sometimes the difference can be subtle, such as when a precaution is already in place but will only be relevant if a condition occurs.
 She can give you advice, in case you need help.
 She can give you advice, if you need help.
The first sentence emphasises that she is prepared to give advice, as a precaution, while the second sentence shows she will give advice if it is needed. The two sentences are very similar, but have grammatically different meanings.

In case
We use in case to talk about taking precautions, doing something because something else might happen:
• During the drought, keep the bath filled with water - just in case it is needed.
• I've bought some candles in case there are more electricity cuts.
• In case I forget, remind me to check the tyre pressure before we load up the car.
In case or if?
When we use in case we are mostly describing future possible situations. When we use if we are talking about conditions that apply. Compare the following and note the differences in meaning.
• I'll fill up the car with petrol in case you need to go to Brighton. ( = I'll fill up now, because you might need it later.)
• I'll fill up the car with petrol if you need to go to Brighton. ( = Let me know if you need to go to Brighton and then I'll fill up with petrol.)
• Take the mobile phone with you in case the car breaks down.
If the car breaks down, give me a ring.
in case of
Note that in case of is a prepositional phrase used with a nounwhich is similar in meaning to an if-clause. Compare the following:
• In case of fire, exit from the building by the stairs. Do not attempt to use the lift.
• If there is a fire, leave the building via the stairs. Don't try to use the lift.
• In cases of difficulty, phone this help line.
If you experience any problems, phone this help line.

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