Let's say i got $url = "image1/pic1.jpg", how can I put the first 5 character to another variable like $newurl?..
Dec 15, 1998, 6:16 PM
Novice (28 posts)
Dec 15, 1998, 6:16 PM
Post #3 of 4
Views: 3925
ok thanks alex, that's what I need. I'm familiar with C and VB but new to PERL. So let's make this clear.
substr(variable, starting char, length)
ins't it?
substr(variable, starting char, length)
ins't it?
Dec 15, 1998, 7:36 PM
Administrator (9387 posts)
Dec 15, 1998, 7:36 PM
Post #4 of 4
Views: 3918
Yes, but more then that is possible as well -- from the perl man pages:
substr EXPR,OFFSET,LEN
substr EXPR,OFFSET
Extracts a substring out of EXPR and returns it. First character is at offset , or whatever you've set $[ to (but don't do that). If OFFSET is negative (or more precisely, less than $[), starts that far from the end of the string. If LEN is omitted, returns everything to the end of the string. If LEN is negative, leaves that many characters off the end of the string.
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.
You can use the substr() function as an lvalue, in which case EXPR must be an lvalue. If you assign something shorter than LEN, the string will shrink, and if you assign something longer than LEN, the string will grow to accommodate it. To keep the string the same length you may need to pad or chop your value using sprintf().
An alternative to using substr() as an lvalue is to specify the replacement string as the 4th argument.
This allows you to replace parts of the EXPR and return what was there before in one operation.
Also, if you want to match a pattern rather then a fixed x characters, use regular expressions instead.
Hope that helps,
Alex
Quote:
substr EXPR,OFFSET,LEN,REPLACEMENT substr EXPR,OFFSET,LEN
substr EXPR,OFFSET
Extracts a substring out of EXPR and returns it. First character is at offset , or whatever you've set $[ to (but don't do that). If OFFSET is negative (or more precisely, less than $[), starts that far from the end of the string. If LEN is omitted, returns everything to the end of the string. If LEN is negative, leaves that many characters off the end of the string.
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.
You can use the substr() function as an lvalue, in which case EXPR must be an lvalue. If you assign something shorter than LEN, the string will shrink, and if you assign something longer than LEN, the string will grow to accommodate it. To keep the string the same length you may need to pad or chop your value using sprintf().
An alternative to using substr() as an lvalue is to specify the replacement string as the 4th argument.
This allows you to replace parts of the EXPR and return what was there before in one operation.
Also, if you want to match a pattern rather then a fixed x characters, use regular expressions instead.
Hope that helps,
Alex