![\"cplusplus.jpg\"](\"http:\/\/bobbeaty.com\/wp\/wp-content\/uploads\/2007\/10\/cplusplus.jpg\" "\\"cplusplus.jpg\\"")
<\/p>\n<\/p>\n
I was working with exchange data today, and realized that the \"timestamp in microseconds since epoch\" wasn't really a great timestamp, and, in fact, the exchanges are using the reference point of midnight, and only to milliseconds. The problem was, I didn't have a simple method that could give me the time with respect to midnight. I didn't see anything that was really helpful on google either.<\/p>\n
Then it hit me... It was like a flash - like all great insights are: use the seconds in the response from gettimeofday()<\/tt> as the input to localtime_r()<\/tt> and then you have one time \"instant\" defined, but you can pick off the hours, minutes, and secons and then add in the milliseconds by dividing the microseconds.<\/p>\n
Like this:<\/p>\n
uint32_t<\/span> TransferStats::<\/span>msecSinceMidnight<\/span>(<\/span>)<\/span>\n {<\/span>\n \/*\n * This is really interesting. I need to get the msec since midnight,\n * and the cleanest way I could think to do this was to get the\n * timeval struct and then take the tv_sec component of it and pass\n * it to localtime_r to get the hour, min, sec parts of the time and\n * then piece it all together again. Kinda slick.\n *\/<\/span>\n \/\/ get the time now as the (sec + usec) since epoch<\/span>\n struct<\/span> timeval tv;<\/span>\n gettimeofday(<\/span>&<\/span>tv, NULL<\/span>)<\/span>;<\/span>\n \/\/ now take the seconds component and get the current hour, min, sec<\/span>\n struct<\/span> tm<\/span> now;<\/span>\n localtime_r(<\/span>&<\/span>tv.tv_sec<\/span>, &<\/span>now)<\/span>;<\/span>\n \/\/ now let's calculate the time since midnight...<\/span>\n return<\/span> (<\/span>tv.tv_usec<\/span>\/<\/span>1000<\/span> +<\/span> (<\/span>(<\/span>now.tm_hour<\/span> *<\/span> 60<\/span> +<\/span> now.tm_min<\/span>)<\/span> *<\/span> 60<\/span>\n +<\/span> now.tm_sec<\/span>)<\/span> *<\/span> 1000<\/span>)<\/span>;<\/span>\n }<\/span><\/pre>\n","protected":false},"excerpt":{"rendered":"I was working with exchange data today, and realized that the “timestamp in microseconds since epoch” wasn’t really a great timestamp, and, in fact, the exchanges are using the reference point of midnight, and only to milliseconds. The problem was, I didn’t have a simple method that could give me the time with respect to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-3796","post","type-post","status-publish","format-standard","hentry","category-coding"],"_links":{"self":[{"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/posts\/3796","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/comments?post=3796"}],"version-history":[{"count":1,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/posts\/3796\/revisions"}],"predecessor-version":[{"id":3797,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/posts\/3796\/revisions\/3797"}],"wp:attachment":[{"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/media?parent=3796"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/categories?post=3796"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bobbeaty.com\/wp\/wp-json\/wp\/v2\/tags?post=3796"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}