{"id":2267,"date":"2011-08-31T21:01:53","date_gmt":"2011-09-01T01:01:53","guid":{"rendered":"http:\/\/www.gubatron.com\/blog\/?p=2267"},"modified":"2011-08-31T21:01:53","modified_gmt":"2011-09-01T01:01:53","slug":"nsis-strcontains-function-find-the-index-of-a-sub-string","status":"publish","type":"post","link":"https:\/\/www.gubatron.com\/blog\/nsis-strcontains-function-find-the-index-of-a-sub-string\/","title":{"rendered":"NSIS: StrContains function – Find the index of a sub string."},"content":{"rendered":"

Recently I was out of internet and I needed to implement a function that would search if a String was part of another String for an NSIS installer.
\nHere’s my rendition of such a function. Once I came back online I found out about StrStr<\/a>, but here’s another option that gives you as output the starting index on the bigger string (aka Haystack) if the smaller string (aka Needle) is found. Otherwise, it returns -1.<\/p>\n

[code]
\n; ————————————————
\n; StrContains
\n; Returns starting index of where a string is contained inside another string (case sensitive)
\n; Usage: !insertmacro StrContains ${HayStack} ${Needle} ${Output}
\n;
\n; Parameters:
\n; HayStack – The string that could contain the substring you’re looking for
\n; Needle – The string you are looking for
\n; Output – -1 if the needle is not in the haystack, or the offset where it exists.<\/p>\n

Var HaystackOffset ;current offset on haystack to copy NeedleLength characters into HayStackBuffer
\nVar HaystackLength ;size of the big string
\nVar MaxHaystackOffset ;maximum offset we can reach
\nVar NeedleLength ;length of string we’re looking for
\nVar HaystackBuffer ;substring we get on each iteration<\/p>\n

!macro StrContains Haystack Needle Output
\n ;we’ll be repeating this operation until we’ve reached
\n ;HayStackLength – NeedleLength<\/p>\n

;Get the lengths of the strings.
\n StrLen $HaystackLength ${Haystack}
\n StrLen $NeedleLength ${Needle}
\n StrCpy $HaystackOffset 0<\/p>\n

;Determine what’s the maximum offset we can use to search for the substring
\n IntOp $MaxHaystackOffset $HaystackLength – $NeedleLength
\n IntOp $MaxHaystackOffset $MaxHaystackOffset – 1<\/p>\n

;Make sure needle is not bigger than haystack
\n IntCmp $NeedleLength $HaystackLength LoopStart LoopStart DidNotFindIt<\/p>\n

DidNotFindIt:
\n StrCpy $HaystackOffset -1
\n Goto Finish<\/p>\n

;Start of substring comparison loop
\n LoopStart:
\n ;copy the substring to a buffer
\n StrCpy $HaystackBuffer ${Haystack} $NeedleLength $HaystackOffset<\/p>\n

;It’s pretty cool if you uncomment this.
\n ;MessageBox MB_ICONINFORMATION|MB_OK "[Loop] Buffer: [$HaystackBuffer] Offset: [$HaystackOffset]"<\/p>\n

;If we’re done, we return the current haystackoffset
\n StrCmpS $HaystackBuffer ${Needle} Finish FigureOutNextStep<\/p>\n

;Did we reach the end, or can we move a bit more
\n FigureOutNextStep:<\/p>\n

;Move offset 1 character to the right and see if we can keep going
\n IntOp $HaystackOffset $HaystackOffset + 1
\n IntCmp $HaystackOffset $MaxHaystackOffset LoopStart LoopStart DidNotFindIt <\/p>\n

Finish:
\n StrCpy ${Output} $HaystackOffset
\n!macroend
\n[\/code] <\/p>\n","protected":false},"excerpt":{"rendered":"

Recently I was out of internet and I needed to implement a function that would search if a String was part of another String for an NSIS installer. Here’s my rendition of such a function. Once I came back online I found out about StrStr, but here’s another option that gives you as output the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[15],"tags":[],"class_list":["post-2267","post","type-post","status-publish","format-standard","hentry","category-code"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5Unzf-Az","jetpack-related-posts":[{"id":2197,"url":"https:\/\/www.gubatron.com\/blog\/nsis-charat-function-macro\/","url_meta":{"origin":2267,"position":0},"title":"NSIS CharAt Macro","author":"gubatron","date":"March 21, 2011","format":false,"excerpt":"Lord knows why the NSIS folks didn't add a CharAt function to their API. In case you need it to parse a string, here's a Macro that makes StrCpy work like a CharAt function [bash] ;Get a character inside a string given an index. ;Usage: CharAt String Index Output !macro\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1269,"url":"https:\/\/www.gubatron.com\/blog\/how-to-make-a-quick-dirty-hexviewer-updated\/","url_meta":{"origin":2267,"position":1},"title":"How to make a Quick & Dirty HexViewer – Updated","author":"gubatron","date":"April 20, 2009","format":false,"excerpt":"After I received comments from ispak on Flickr I made a few fixes. ispak pointed out that it was a bad idea reading one byte at the time, also I had a gay ass try\/catch that didn't catch any exception :p So now I read 16 byte chunks, and I\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"HexViewer - r2","src":"https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=350%2C200 1x, https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=525%2C300 1.5x"},"classes":[]},{"id":2792,"url":"https:\/\/www.gubatron.com\/blog\/java-have-a-jtables-column-preferred-width-adjusted-to-perfectly-to-the-size-of-the-longest-string-in-the-model\/","url_meta":{"origin":2267,"position":2},"title":"Java: Have a JTable’s column preferred width adjusted perfectly to the size of the longest string in the model","author":"gubatron","date":"October 30, 2012","format":false,"excerpt":"Here's a utility method I've coded for FrostWire's partial download dialog. 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