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Why is the regex to match numbers from 1 to 10 commonly written as follows?
[1-9]|10 Instead of:
[1-10] Or this:
[1-(10)] 
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To match any number from 0 to 9 we use \d in regex. It will match any single digit number from 0 to 9. \d means [0-9] or match any number from 0 to 9. Instead of writing 0123456789 the shorthand version is [0-9] where [] is used for character range.
To match a character having special meaning in regex, you need to use a escape sequence prefix with a backslash ( \ ). E.g., \. matches "." ; regex \+ matches "+" ; and regex \( matches "(" . You also need to use regex \\ to match "\" (back-slash).
Basically (0+1)* mathes any sequence of ones and zeroes. So, in your example (0+1)*1(0+1)* should match any sequence that has 1. It would not match 000 , but it would match 010 , 1 , 111 etc. (0+1) means 0 OR 1.
Sometime a good drawing worth 1000 words...
Here are the three propositions in your question and the way a regex flavour would understand them:
Invalid regexp !! This regex is invalid because a range is opened (1-) with a digit but not closed with another digit (ends with ().
A range is usually bound with digits on both sides or letters on both sides.
Images generated with Debuggex
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