{"id":5963,"date":"2022-08-31T17:21:35","date_gmt":"2022-08-31T11:51:35","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/"},"modified":"2022-08-31T17:21:35","modified_gmt":"2022-08-31T11:51:35","slug":"solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/","title":{"rendered":"[Solved] How to do multiple value replacement in a multiple line at one time"},"content":{"rendered":"

[ad_1]
\n<\/p>\n

\n
\n
<\/div>\n
\n
\n

By now the question has assumed form. I take it that you want to change the number in { }<\/code> on a particular line in the file. The posted code got close and I’ll comment on basics and complete it.<\/p>\n

Since we now find the number inside { }<\/code> there is no need for the hard-coded $old_value<\/code>. In order to identify the desired line you need to match the $old_parameter<\/code> so the condition becomes if (\/$old_parameter\/)<\/code>. A comment on regex matching<\/a> follows, related only to what is used in the code. Please read documentation and books for more.<\/p>\n

Consider while (my $line = <$fh>)<\/code>. A line is read from the file via $fh<\/code> by the diamond operator <><\/code><\/em><\/a> and assigned to a variable $line<\/code>. If you leave out the variable and write only while (<$fh>)<\/code> then the line is assigned to a special variable called $_<\/code>. This variable is often used as a default in Perl. See General Variables<\/a>.<\/p>\n

To check whether a pattern is in a variable, to “match<\/em>” it, we say $var =~ m\/$patt\/<\/code>. This returns true or false in scalar context<\/em> while in list context<\/em> it returns the matches. See Extracting Matches<\/a>. A pattern is best placed into a variable by $patt = qr(...)<\/code>. Our line is in $_<\/code> so we need $_ =~ m\/$patt\/<\/code>, where m<\/code> may be omitted. Regex also allows a shortcut, since it works by default on $_<\/code>, and we may say \/$patt\/<\/code>. Thus if (\/...\/)<\/code>. <\/p>\n

Now consider substitution<\/a>. To find a pattern and replace it we say $var =~ s\/$patt\/$repl\/<\/code>. This changes $var<\/code> “in-place<\/em>“, meaning that after that statement $var<\/code> is changed. If the $patt<\/code> wasn’t found in $var<\/code> nothing happens to it. With our line in $_<\/code> we again need $_<\/code> instead of $var<\/code>, but the same shortcut works and we can say s\/$patt\/$repl\/<\/code>.<\/p>\n

Your code has this \u2013 but it doesn’t do anything with it. The result is never given by the program. An easy way is to print every line and the output can be redirected to a file. Or write lines to a file.<\/p>\n

Now for the needed regex. You want a number inside of { }<\/code>. According to the data you show it is the only such pattern in the line. Then this will do<\/p>\n

s\/ \\{ \\s* \\d+ \\s* \\} \/{$new_value}\/x;\n<\/code><\/pre>\n
The \/x<\/code> allows us to use spaces for readibilty. (Otherwise they would be looked for in the string!)  A digit is matched by \\d<\/code>, and +<\/code> means all that come together, but at least one. In a123b<\/code> it matches 123<\/code>, in a12b3c<\/code> it matches 12<\/code>. The {<\/code> and }<\/code> are escaped since they have a special meaning in a regex. The \\s*<\/code> allows for any number of spaces, or for none. <\/p>\n
The replacement side of the regex says to replace all that has been matched with {$new_value}<\/code>.  There we don’t have to escape {<\/code>, }<\/code>. If you need to capture<\/em> (remember) what has been matched place the pattern in between ()<\/code>. Here you can say<\/p>\n
s\/ (\\{ \\s*) (\\d+) (\\s* \\}) \/$1$new_value$3\/x;\n<\/code><\/pre>\n
and have the original spaces preserved. The first capture is stored in $1<\/code>, the second in $2<\/code>, etc. If the $new_value<\/code> changes during the loop you can compute it before the substitution.<\/p>\n
Please see the answer by Schwern and the technique offered in a comment by ikegami.<\/p>\n
Then we only need to print the line.  The full program<\/p>\n
use warnings 'all';\nuse strict;\n\nmy $old_parameter=\"stack overflow version\";\nmy $new_value = 20;\n\nmy $filename=\"input.txt\";\n\nopen my $fh, \"<\", $filename or die \"Can't open $filename: $!\";\n\nwhile ( <$fh> ) \n{\n    if (\/$old_parameter\/) \n    {\n        s\/\\{\\s* (\\d+) \\s*\\}\/{$new_value}\/x;\n    }\n    print;\n}\n<\/code><\/pre>\n
The print;<\/code> uses the same default, $_<\/code>, and means print $_;<\/code>.  It is after the condition so that all lines are printed, changed or not. A few other errors have been fixed. An amusing one is the following: your $old_parameter<\/code> has “stack overfolw<\/strong> version<\/em>” (misspelled) so it never<\/em> matches the line.<\/p>\n
Finally, please read through perlretut<\/a>, or better yet, through a nice chapter on regular expressions from a book or a tutorial that you are working with<\/em>.<\/p>\n<\/p><\/div>\n
<\/div>\n<\/div>\n
            6<\/span> <\/p><\/div>\n<\/div>\n
[ad_2]<\/p>\n
solved How to do multiple value replacement in a multiple line at one time <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] By now the question has assumed form. I take it that you want to change the number in { } on a particular line in the file. The posted code got close and I’ll comment on basics and complete it. Since we now find the number inside { } there is no need for … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[442],"class_list":["post-5963","post","type-post","status-publish","format-standard","hentry","category-solved","tag-perl"],"yoast_head":"\n[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] By now the question has assumed form. I take it that you want to change the number in { } on a particular line in the file. The posted code got close and I’ll comment on basics and complete it. Since we now find the number inside { } there is no need for ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-08-31T11:51:35+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/person\\\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] How to do multiple value replacement in a multiple line at one time\",\"datePublished\":\"2022-08-31T11:51:35+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/\"},\"wordCount\":592,\"publisher\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\"},\"keywords\":[\"perl\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/\",\"name\":\"[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#website\"},\"datePublished\":\"2022-08-31T11:51:35+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] How to do multiple value replacement in a multiple line at one time\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#website\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/jassweb.com\\\/wp-content\\\/uploads\\\/2021\\\/02\\\/jass-website-logo-1.png\",\"contentUrl\":\"https:\\\/\\\/jassweb.com\\\/wp-content\\\/uploads\\\/2021\\\/02\\\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/logo\\\/image\\\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/person\\\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"contentUrl\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\\\/\\\/jassweb.com\"],\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/author\\\/jaspritsinghghumangmail-com\\\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb","og_description":"[ad_1] By now the question has assumed form. I take it that you want to change the number in { } on a particular line in the file. The posted code got close and I’ll comment on basics and complete it. Since we now find the number inside { } there is no need for ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/","og_site_name":"JassWeb","article_published_time":"2022-08-31T11:51:35+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"3 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] How to do multiple value replacement in a multiple line at one time","datePublished":"2022-08-31T11:51:35+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/"},"wordCount":592,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["perl"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/","url":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/","name":"[Solved] How to do multiple value replacement in a multiple line at one time - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-08-31T11:51:35+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-how-to-do-multiple-value-replacement-in-a-multiple-line-at-one-time\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] How to do multiple value replacement in a multiple line at one time"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/5963","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=5963"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/5963\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=5963"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=5963"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=5963"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}