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For case 1:
Search using:
^([^_]*_)[^_]*
And replace by:
$1
For case 2:
Search using:
^((?:[^_]*_){2})[^_]*
And replace by:
$1
For case 3:
Search using:
^((?:[^_]*_){3})[^_]*
And replace by:
$1
0
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solved Regex Split String on Delimiter