如何使用strcpy将字符串数组存储到结构中？

Question

I am making a small ANSI C application using GCC in Ubuntu, which requires the use of strcpy().

My header file:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define DECKSZ 52

typedef struct card {
    enum {ACE=1, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING} pips;
    enum {SPADES, CLUBS, HEARTS, DIAMONDS} suit;
    char cardName[20];
} card;

extern card deck[];

void initDeck(card[]);
void labelCards();
void shuffleDeck(card[]);
void swap(card*,card*);

My main file:

#include "CardOps.h"

card deck[DECKSZ];

void initDeck(card deck[]) {
    int counter;
    for (counter = 0; counter < DECKSZ; counter++) {
        deck[counter].pips = (const)((counter % 13) + 1);
        deck[counter].suit = (const)(counter / 13);
    }
}

void labelCards(card deck[]) {
    static const char *pipNames[] = {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Jack","Queen","King"};
    static const char *suitNames[] = {"Spades","Hearts","Diamonds","Clubs"};
    int i;
    for (i = 0; i < DECKSZ; i++) {
        strcpy(deck[i].cardName, pipNames[i]);
        /*strcpy(cardName, suits[i]);*/
    }
}

int displayCards(card deck[], int numCards) {
    int i, countCards;
    if (numCards > 52)
        countCards = 52;
    else
        countCards = numCards;
    for (i = 0; i < countCards; i++) {
        printf(deck[i].cardName);
    }
    return countCards;
}

void shuffleDeck(card deck[]) {
    int i, j;
    for (i = 0; i < DECKSZ; i++) {
        j = rand() % DECKSZ;
        swap(&deck[i], &deck[j]);
    }
}

void SortCards() {

}

void swap(card *c1, card *c2) {
    card temp;
    temp = *c1;
    *c1 = *c2;
    *c2 = temp;
}

int main(void) {
    initDeck(deck);
    /*labelCards(deck);*/
    displayCards(deck,52);
    shuffleDeck(deck);
    return EXIT_SUCCESS;
}

I am having trouble with getting strcpy() working within my labelCards() function. Would somebody please help me with strcpy()? Thanks!

Answer 1

I think you'd be better off using sprintf than strcpy . This is because sprintf returns an integer that tells you how many chars you wrote to the destination buffer. With that knowledge you know where to start writing when you want to write the suit.

 //copy the name into the buffer at cardname
int written = sprintf(deck[i].cardName, "%s" pipNames[i%13]);
 //copy the suit name into the same buffer, but advanced by however many chars we just wrote
sprintf(deck[i].cardName + written, "%s", suits[i/13]);

Now it will say things like FiveHearts, and AceClubs.... not optimal, but you can work from here.

Edit: user3386109 suggests an approach much smarter than mine:

sprintf(deck[i].cardName, "%s of %s", pipNames[i%13], suits[i/13] );

One sprintf is definitely better than the two I was doing. There are some cases where knowing how to continue writing where you left off with sprintf is valuable, but this is not one of them. I've also corrected the logic for the indices in pipNames and suits according to user3386109's amendments.

Answer 2

In:

void labelCards(card deck[]) {
    static const char *pipNames[] = {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Jack","Queen","King"};
    static const char *suitNames[] = {"Spades","Hearts","Diamonds","Clubs"};
    int i;
    for (i = 0; i < DECKSZ; i++) {
        strcpy(deck[i].cardName, pipNames[i]);
        /*strcpy(cardName, suits[i]);*/
    }
}

pipNames[i] accesses a non-existing array element when i > 12 .

You need to do pipNames[i % 13] as you do in initDeck . It feels like the labeling should be in initDeck function.