Regular expression to match nine-digit numbers that start with a 1

I am trying to match 9-digit numbers that start with a 1

"/^1[0-9]{9}$/开发者_如何转开发"

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/^1\d{8}/

The first number 1 will be your first digit, so the quantifier should be 8.

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^(?=1)\d{9}$⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ ⁠ 

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The space is \s

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If you need 9 numbers starting with one then you only need to limit the repetition of the character class to eight (8):

"/^1[0-9]{8}$/"

In your sample you have "\ ". If you need to allow spaces use a space or \s for whitespace: [0-9 ] or [0-9\s].