# A Better Poker Hand Evaluator in C++

Still working on my poker game simulation, and now I got to the hand evaluation part. I had written a small C program to do it a while ago, but taking a look at it now, well, all I can say is it was pretty awful. I didn’t sort the cards on that program, so evaluating all the possible hands was a mess…

I wrote a much cleaner version now (in C++) with sorting upfront. There you go:

``````class Card{
public:
int suit;
int rank;
};

int compareCards(const void *card1, const void *card2){
return (*(Card *)card1).rank - (*(Card *)card2).rank;
}

int evaluateHand(Card hand[]){
qsort(hand,5,sizeof(Card),compareCards);
int straight,flush,three,four,full,pairs;
int k;

straight = flush = three = four = full = pairs = 0;
k = 0;

/*checks for flush*/
while (k<4&&hand[k].suit==hand[k+1].suit)
k++;
if (k==4)
flush = 1;

/* checks for straight*/
k=0;
while (k<4&&hand[k].rank==hand[k+1].rank-1)
k++;
if (k==4)
straight = 1;

/* checks for fours */
for (int i=0;i<2;i++){
k = i;
while (k<i+3&&hand[k].rank==hand[k+1].rank)
k++;
if (k==i+3)
four = 1;
}

/*checks for threes and fullhouse*/
if (!four){
for (int i=0;i<3;i++){
k = i;
while (k<i+2&&hand[k].rank==hand[k+1].rank)
k++;
if (k==i+2){
three = 1;
if (i==0){
if (hand[3].rank==hand[4].rank)
full=1;
}
else if(i==1){
if (hand[0].rank==hand[4].rank)
full=1;
}
else{
if (hand[0].rank==hand[1].rank)
full=1;
}
}
}
}

if (straight&&flush)
return 9;
else if(four)
return 8;
else if(full)
return 7;
else if(flush)
return 6;
else if(straight)
return 5;
else if(three)
return 4;

/* checks for pairs*/
for (k=0;k<4;k++)
if (hand[k].rank==hand[k+1].rank)
pairs++;

if (pairs==2)
return 3;
else if(pairs)
return 2;
else
return 1;
}``````

## 4 thoughts on “A Better Poker Hand Evaluator in C++”

1. Stepan

Mike, who told you that? It’s called wheel straight or smthn.

Anyways there is much to hand evaluation than implemented here.

1. jim

I know this is old, but IMHO a better way is to first compute a histogram of suits and ranks. If one of the rank bins is 4 you’ve got 4 of a kind. If one is 3 and another 2 a boat. If a suit bin has 5 cards you have a flush. etc etc etc.

For straights, if hi card – lo card == 4 you’ve got a straight, special case being an ace high straight.

And yeah, A-5 and 10-A are both straights.