How we can add two condition in one if function

Answer 1

I believe you are thinking of the and statement which is represented in c++ by the "&&"

If (firstCondition && secondCondition){
/*something will happen if both conditions are met*/
}

Answer 2

Use logical operators:
if((x>=3)&&(x<=8)) for example is true then x greater or equals 3 and less or equals 8

Answer 3

Well, you can always use &&. I'm not sure what you're asking here, though :)

Answer 4

You can use && if you want the two condition corect, or use || if you want either of the two condition is correct, :)