{"id":1929,"date":"2016-02-28T10:22:48","date_gmt":"2016-02-28T15:22:48","guid":{"rendered":"http:\/\/bitpost.com\/news\/?p=1929"},"modified":"2016-02-28T10:58:21","modified_gmt":"2016-02-28T15:58:21","slug":"reliable-c-regular-expressions-in-10-minutes","status":"publish","type":"post","link":"https:\/\/bitpost.com\/news\/2016\/reliable-c-regular-expressions-in-10-minutes\/","title":{"rendered":"Reliable C++ regular expressions in 10 minutes"},"content":{"rendered":"

I gave myself an hour to add multi-line search-and-replace support in my code. \u00a0It took 3, and C++11 std::regex_replace() gave me a hard crash with inline replacement. \u00a0The syntax can be annoying (for example, using double escape), so for reference, here’s a jumpstart.<\/p>\n

Given:<\/p>\n

using namespace std;\r\nstring str = \"Lots of text to search\\nacross lines\";\r\nstring from = \"text[\\\\s\\\\S]*lines\";\r\nstring to = \"rainbows\";<\/code><\/pre>\n
Boost happily did the job:<\/p>\n
#include \r\n boost::regex reg;\r\n reg.assign(from);\r\n str = boost::regex_replace(str,reg,to,boost::match_default);<\/code><\/pre>\n
C++11 is even simpler, but it crashes with gcc 4.9.2 if you use the same string for source and target<\/strong>, like this:<\/p>\n
#include \r\n std::regex reg(from);\r\n str = std::regex_replace(str,reg,to);<\/code><\/pre>\n
You can fix that by using a swap string:<\/p>\n
#include \r\n regex reg(from);\r\n string newstr = regex_replace(str,reg,to);\r\n str = newstr;<\/code><\/pre>\n
But it isn’t\u00a0working across lines, with this particular syntax, and I’ve seen others complain that they couldn’t get multiline\u00a0syntax going. \u00a0I’ll stick with boost for now until this smooths out a little bit more. \u00a0Onwards.<\/p>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
I gave myself an hour to add multi-line search-and-replace support in my code. \u00a0It took 3, and C++11 std::regex_replace() gave me a hard crash with inline replacement. \u00a0The syntax can be annoying (for example, using double escape), so for reference, here’s a jumpstart. Given: using namespace std; string str = “Lots of text to search\\nacross […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_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},"jetpack_post_was_ever_published":false},"categories":[204,22,19],"tags":[190,55],"class_list":["post-1929","post","type-post","status-publish","format-standard","hentry","category-a-better-trader","category-cpp","category-opensource","tag-c11","tag-regex"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t