{"id":3799,"date":"2019-10-19T00:01:18","date_gmt":"2019-10-19T07:01:18","guid":{"rendered":"https:\/\/c-for-dummies.com\/blog\/?p=3799"},"modified":"2019-10-26T08:43:39","modified_gmt":"2019-10-26T15:43:39","slug":"four-of-a-kind-three-of-a-kind-and-a-full-house-poker-vii","status":"publish","type":"post","link":"https:\/\/c-for-dummies.com\/blog\/?p=3799","title":{"rendered":"Four-of-a-Kind, Three-of-a-kind, and a Full House (Poker VII)"},"content":{"rendered":"

To effectively evaluate poker hands, the next sequence after a straight, straight flush, and flush draw (covered in last week’s Lesson<\/a>) is to evaluate four-of-a-kind, then three-of-a-kind, and (while you’re at it) a full house.
\n
\nAfter the hand of playing cards is sorted by value, the four-of-a-kind test has only two possible solutions: the first four cards all have the same value or the last four cards all have the same value. Here’s the fourkind()<\/em> function I wrote to test both conditions:<\/p>\n

\r\n\/* only two possible hand patterns for\r\n   four-of-a-kind *\/<\/span>\r\nint fourkind(struct playing_card p[])\r\n{\r\n    \/* test the first four cards *\/<\/span>\r\n    if( p[0].value==p[1].value && p[1].value==p[2].value && p[2].value==p[3].value )\r\n        return(TRUE);\r\n    \/* test the last four cards *\/<\/span>\r\n    if( p[1].value==p[2].value && p[2].value==p[3].value && p[3].value==p[4].value )\r\n        return(TRUE);\r\n\r\n    return(FALSE);\r\n}<\/pre>\n
The if<\/em> statements are logically complex but serve the task of identifying the two possible patterns for a four-of-a-kind draw. When all the card values compare positively, TRUE<\/code> is returned.<\/p>\n
I used a similar approach to evaluate a three-of-a-kind draw. In this pattern, the first three cards, middle three cards, or last three cards must have the same values to generate a true condition. Here is my threekind()<\/em> function:<\/p>\n
\r\n\/* three possible hand patterns for\r\n   three-of-a-kind *\/<\/span>\r\nint threekind(struct playing_card p[])\r\n{\r\n    \/* test the first three cards *\/<\/span>\r\n    if( p[0].value==p[1].value && p[1].value==p[2].value )\r\n        return(TRUE);\r\n    \/* test the next three cards *\/<\/span>\r\n    if( p[1].value==p[2].value && p[2].value==p[3].value )\r\n        return(TRUE);\r\n    \/* test the last three cards *\/<\/span>\r\n    if( p[2].value==p[3].value && p[3].value==p[4].value )\r\n        return(TRUE);\r\n\r\n    return(FALSE);\r\n}<\/pre>\n
Hand 1: 5♦ 5♠ 6♦ 9♦ 9♥
\nHand 2: 2♠ 4♠ 6♠ 10♠ K♠ - Flush
\nHand 3: 6♠ 7♣ 7♥ 9♥ J♦
\nHand 4: 4♥ 5♥ 6♥ 7♥ 8♥ - Straight Flush
\nHand 5: A♠ A♥ A♦ A♣ K♥ - Four-of-a-kind
\nHand 6: A♦ 4♣ 4♠ 4♥ 4♦ - Four-of-a-kind
\nHand 7: 5♠ 5♣ 5♦ 9♣ J♥ - Three-of-a-kind
\nHand 8: A♠ 9♥ 9♦ 9♣ Q♥ - Three-of-a-kind
\nHand 9: A♠ A♥ K♦ K♣ K♥ - Three-of-a-kind<\/code><\/p>\n
The next logical hand to evaluate is a full house, which is a combination three-of-a-kind and a pair. After much sweat and gnashing of teeth, I determined that a separate fullhouse()<\/em> function would be redundant to the threekind()<\/em> function. So I modified the threekind()<\/em> function to also detect a full house:<\/p>\n
\r\n\/* three possible hand patterns for\r\n   three-of-a-kind  - and full house *\/<\/span>\r\nint threekind(struct playing_card p[])\r\n{\r\n    \/* test the first three cards *\/<\/span>\r\n    if( p[0].value==p[1].value && p[1].value==p[2].value )\r\n    {\r\n        \/* also test for full house *\/<\/span>\r\n        if( p[3].value==p[4].value )\r\n            return(2);\r\n        else\r\n            return(1);\r\n    }\r\n\r\n    \/* test the next three cards *\/<\/span>\r\n    if( p[1].value==p[2].value && p[2].value==p[3].value )\r\n        return(TRUE);\r\n    \r\n    \/* test the last three cards *\/<\/span>\r\n    if( p[2].value==p[3].value && p[3].value==p[4].value )\r\n    {\r\n        \/* also test for a full house *\/<\/span>\r\n        if( p[0].value==p[1].value )\r\n            return(2);\r\n        else\r\n            return(1);\r\n    }\r\n\r\n    return(FALSE);\r\n}<\/pre>\n
With the cards in the hand sorted, only two arrangements are possible for a full house: a pair and three-of-a-kind or three-of-a-kind and a pair. The first and last if<\/em> tests in the threekind()<\/em> function check for both conditions.<\/p>\n
I also modified the return values from this function: FALSE<\/code>, or zero, means no pattern was found; 1 (TRUE<\/code>) means the function found a three-of-a-kind match; 2 is returned for a full house. Modifications were also made to the main()<\/em> function both to show sample full house draws in the hand[][]<\/code> array.<\/p>\n
Click here<\/a> to view the full code on Github. Here’s a sample run:<\/p>\n
Hand 1: 5♦ 5♠ 6♦ 9♦ 9♥
\nHand 2: 2♠ 4♠ 6♠ 10♠ K♠ - Flush
\nHand 3: 6♠ 7♣ 7♥ 9♥ J♦
\nHand 4: 4♥ 5♥ 6♥ 7♥ 8♥ - Straight Flush
\nHand 5: A♠ A♥ A♦ A♣ K♥ - Four-of-a-kind
\nHand 6: A♦ 4♣ 4♠ 4♥ 4♦ - Four-of-a-kind
\nHand 7: 5♠ 5♣ 5♦ 9♣ 9♥ - Full House
\nHand 8: A♠ 9♥ 9♦ 9♣ Q♥ - Three-of-a-kind
\nHand 9: A♠ A♥ K♦ K♣ K♥ - Full House<\/code><\/p>\n
In next week’s Lesson<\/a> I add the final function, pairs()<\/em>, which checks for one or two pairs.<\/p>\n","protected":false},"excerpt":{"rendered":"
The tests for my poker program proceed, identifying a few high-ranking hands. Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-3799","post","type-post","status-publish","format-standard","hentry","category-main"],"_links":{"self":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3799","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3799"}],"version-history":[{"count":6,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3799\/revisions"}],"predecessor-version":[{"id":3825,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/3799\/revisions\/3825"}],"wp:attachment":[{"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3799"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3799"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c-for-dummies.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3799"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
After coding these two functions, I ran some tests. I updated the playing_card<\/em> hand[][]<\/code> array to add some positives for four-of-a-kind and three-of-a-kind draws, as well as keeping some of the positive matches for straights and flushes. You can view the full code for this draft on Github<\/a>. Here’s sample output:<\/p>\n