c - int 与 char[2] 错误的间接级别不同

Question

代码来自 Absolute beginner's guide to C，我得到这个错误 ./BlackJack.c<41> : warning C4047: '==' : 'int' differes in levels of indirection from 'char [2]'当我尝试在 Visual Studio 中编译它时。这是二十一点游戏的主要功能。

第 <41> 行是 if (ans == "H") {

main()
{
    int numCards; /* Equals 52 at the beginneing */
    int cards[52], playerPoints[2], dealerPoints[2], total[2]; 
    /* For user Hit/Stand or     Yes/No response */

    do { initCardsScreen(cards, playerPoints, dealerPoints, total, &numCards);
        dealerGetsCard(&numCards, cards, dealerPoints);
        printf("\n");
        playerGetsCard(&numCards, cards, playerPoints);
        playerGetsCard(&numCards, cards, playerPoints);
        do {
            ans = getAns("Hit or stand (H/S)? ");
            if (ans == "H") { 
                platerGetsCard(&numCards, cards, playerPoints); 
            }
        }
        while ( ans != 'S');
        totalIt(playerPoints, total, PLAYER);
        /* Player's total */
        do {
            dealerGetsCard(&numCards, cards, dealerPoints);
        } while (dealerPoints[ACEHIGH] < 17);
        /* 17: Dealer stop */
        totalIt(dealerPoints, total, DEALER);
        /* Dealer's total */
        findWinner(total);
        ans = getAns("\nPlay again (Y/N)? ");
    } while (ans == 'Y');
    return;
}

(更新):这是完整的代码。

#include <stdio.h>
#include <time.h>
#include <ctype.h>
#include <stdlib.h>

#define BELL '\a'
#define DEALER 0
#define PLAYER 1

#define ACELOW 0
#define ACEHIGH 1

int askedForName = 0;

/****************************
This program specific prototype
****************************/
void dispTitle(void);
void initCardsScreen(int cards[52], int playerPoints[2], int dealerPoints[2], int total[2], int * numCards);
int dealCard(int * numCards, int cards[52]);
void dispCard(int cardDrawn, int points[2]);
void totalIt(int points[2], int total[2], int who);
void dealerGetsCard(int *numCards, int cards[52], int dealerPoints[2]);
void playerGetsCard(int *numCards, int cards[52], int playerPoints[2]);
char getAns(char mesg[]);
char ans;
void findWinner(int total[2]);


main()
{
    int numCards; /* Equals 52 at the beginneing */
    int cards[52], playerPoints[2], dealerPoints[2], total[2]; /* For user Hit/Stand or Yes/No response */

    do { initCardsScreen(cards, playerPoints, dealerPoints, total, &numCards);
    dealerGetsCard(&numCards, cards, dealerPoints);
    printf("\n");
    playerGetsCard(&numCards, cards, playerPoints);
    playerGetsCard(&numCards, cards, playerPoints);
    do {
        char ans = getAns("Hit or stand (H/S)? ");
        if (ans == "H") { 
            playerGetsCard(&numCards, cards, playerPoints); 
        }
    }
    while ( ans != 'S');
    totalIt(playerPoints, total, PLAYER);
    /* Player's total */
    do {
        dealerGetsCard(&numCards, cards, dealerPoints);
    } while (dealerPoints[ACEHIGH] < 17);
    /* 17: Dealer stop */
    totalIt(dealerPoints, total, DEALER);
    /* Dealer's total */
    findWinner(total);
    ans = getAns("\nPlay again (Y/N)? ");
    } while (ans == 'Y');
    return;
}

void initCardsScreen(int cards[52], int playerPoints[2], int dealerPoints[2], int total[2], int *numCards)
{
    int sub, val=1; /* This function's Work variables */
    char firstName[15]; /* Holds user's first name */
    *numCards = 52; /* Holds running total of number of cards */

    for (sub = 0; sub <= 51; sub++) { /* Counts from 0 to 51 */
        val = (val == 14) ? 1 : val; /* If val is 14 reset to 1 */
        cards[sub] = val;
        val++; }
    for (sub = 0; sub <= 1; sub++) { /* Counts from 0 to 1 */
        playerPoints[sub] = dealerPoints[sub] = total[sub]=0; }
    dispTitle();
    if (askedForName ==0) { /* Name asked for nly once */
        printf("\nWhat is your first name? ");
        scanf_s(" %s", firstName);
        askedForName = 1; /* Don't ask prompt again */
        printf("Ok, %s, get ready for casino action!\n\n", firstName);
        getchar(); /* Discards newline. You can safely */
    }           /* ignore compiler warning here. */
    return;
}

/*** This function gets a card for the player and updates the player's points. ***/
void playerGetsCard(int *numCards, int cards[52], int playerPoints[2])
{
    int newCard;
    newCard = dealCard(numCards, cards);
    printf("You draw: ");
    dispCard(newCard, playerPoints);
}

/*** This function gets a card for the dealer and updates the dealer's poimts. ***/
void dealerGetsCard(int *numCards, int cards[52], int dealerPoints[2])
{
    int newCard;
    newCard = dealCard(numCards, cards);
    printf("The dealer draws: ");
    dispCard(newCard, dealerPoints);
}

/*** This function gets a card from the deck and stores it in either the dealer's or the player's hold of cards ***/
int dealCard(int * numCards, int cards[52])
{
    int cardDrawn, subDraw;
    time_t t; /* Gets time for a random value */
    srand((unsigned int)(time(&t)));  /* Seeds random-number generator */
    subDraw = (rand() % (*numCards)); /* From 0 to numcards */
    cardDrawn = cards[subDraw]; 
    cards[subDraw] = cards[*numCards -1]; /* Puts top card */
    (*numCards); /* in place of drawn one */
    return cardDrawn;
}

/*** Displays the last drawn card and updates points with it. ***/
void dispCard(int cardDrawn, int points[2])
{
    switch (cardDrawn) {
    case(11) : printf("%s\n", "Jack");
        points[ACELOW] += 10;
        points[ACEHIGH] += 10;
        break;
    case(12) : printf("%s\n", "Queen");
        points[ACELOW] += 10;
        points[ACEHIGH] += 10;
        break;
    case(13) : printf("%s\n", "King");
        points[ACELOW] += 10;
        points[ACEHIGH] += 10;
        break;
    default : points[ACELOW] += cardDrawn;
        if (cardDrawn == 1)
        { 
            printf("%s\n", "Ace");
            points[ACEHIGH] += 11;
        }
        else
        {
            points[ACEHIGH] += cardDrawn;
            printf("%d\n", cardDrawn); 
        }
    } return;
}

/*** Figure the total for player or dealer to see who won. This function takes into account the fact that Ace is either 1 or 11. ***/
void totalIt(int points[2], int total[2], int who)
{
    /* The following routine first looks to see if the total points counting Aces as 1 is equal to the total points couning Aces as 11. If so, 
    or if the total points counting Aces as 11 is more than 21, the program uses the total with Aces as 1 only */
    if ((points[ACELOW] == points[ACEHIGH]) || (points[ACEHIGH] > 21)) {
        total[who] = points[ACELOW]; /* Keeps all Aces as 1 */
    }
    else {
        total[who] = points[ACEHIGH]; /* Keeps all Aces as 11 */
    }
    if (who == PLAYER) /* Determines the message printed */ {
        printf("You have a total of %d\n\n", total[PLAYER]);
    }
    else {
        printf("The house stands with a total of %d\n\n", total[DEALER]);
    }
    return;
}

/*** Prints the winning player. ***/
void findWinner(int total[2])
{
    if (total[DEALER] == 21) {
        printf("The house wins.\n");
        return;
    }
    if ((total[DEALER] > 21) && (total[PLAYER] > 21)) { 
        printf("%s", "Nobody wins.\n");
        return;
    }
    if ((total[DEALER] >= total[PLAYER]) && (total[DEALER] < 21)) {
        printf("The house wins.\n");
        return;
    }
    if ((total[PLAYER] > 21) && (total[DEALER] < 21)) {
        printf("The house wins.\n");
        return;
    }
    printf("%s%c", "You win!\n", BELL);
    return;
}

/*** Gets the user's uppercase, single-character response. ***/
char getAns(char mesg[])
{
    char ans;
    printf("%s", mesg); /* Prints the prompt message passed */
    ans = getchar();
    getchar(); /* Discards newline. You can safely ignore compiler warning here. */
    return toupper(ans);
}

/*** Clears everything off the screen. ***/
void dispTitle(void)
{
    int i=0;
    while (i < 25) { /* Clears screen by printing 25 blank lines to 'push off' stuff that
                     might be left over on the screen before this program */
        printf("\n");
        i++;
    }
    printf("\n\n*Step right up to the Blackjack tables*\n\n");
    return;
}

Answer 1

请注意所有其他比较都是如何用单引号引起来的？

while (ans == 'Y')

在那里，您正在比较单个字符(这是一个数字，因此可以与另一个数字进行比较)。

另一方面，在失败的代码中，您使用了双引号。

ans == "H"

因此，您正在与一个字符串进行比较，它是一个字符数组。该数组有两个字符长以容纳 null terminator .