perlfunc
gods
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substr - get or alter a portion of a stirng
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substr
<FONT SIZE=-1>EXPR,OFFSET,LEN,REPLACEMENT</FONT>
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substr
<FONT SIZE=-1>EXPR,OFFSET,LEN</FONT>
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substr
<FONT SIZE=-1>EXPR,OFFSET</FONT>
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Extracts a substring out of
<FONT SIZE=-1>EXPR</FONT> and returns it. First character is at offset <CODE>0</CODE>, or whatever you've set <CODE>$[</CODE> to (but don't do that). If
<FONT SIZE=-1>OFFSET</FONT> is negative (or more precisely, less than <CODE>$[</CODE>), starts that far from the end of the string. If
<FONT SIZE=-1>LEN</FONT> is omitted, returns everything to the end of the string. If
<FONT SIZE=-1>LEN</FONT> is negative, leaves that many characters off the end of the string.
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If you specify a substring that is partly outside the string, the part
within the string is returned. If the substring is totally outside the
string a warning is produced.
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You can use the [perlfunc:substr|substr()] function as an lvalue, in which case
<FONT SIZE=-1>EXPR</FONT> must be an lvalue. If you assign something shorter than
<FONT SIZE=-1>LEN,</FONT> the string will shrink, and if you assign something longer than
<FONT SIZE=-1>LEN,</FONT> the string will grow to accommodate it. To keep the string the same length you may need to pad or chop your value using
[perlfunc:sprintf|sprintf()].
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An alternative to using [perlfunc:substr|substr()] as an lvalue is to specify the replacement string as the 4th argument. This allows you to replace parts of the
<FONT SIZE=-1>EXPR</FONT> and return what was there before in one operation.
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