c - 函数返回字符数组的C问题

Question

这是我正在处理的作业的头文件中的一个函数。

#ifndef CARDGAMES_H
#define CARDGAMES_H

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

typedef struct {
    char suit;
    char label;
    int value;
} card ;

//function prototypes (removed the majority of them, this is just a segment of header file)

void addToDeck(card deck[], card toAdd, int * deckLength);
void printDeck(card deck[], int deckLength);

card removeCard(card deck[], int * deckLength, int index);


*/
card removeCard(card deck[], int * deckLength, int index){
        card removed = deck[index];
        int x = *deckLength;
        deck[index] = deck[x];
        deck[x] = removed;
        x=x-1;
        *deckLength = x;
        return removed;

以下是我正在测试此功能的驱动程序的一部分......我的问题出现了。

printf("\tThe deck after adding the ten of hearts: \n");
    printDeck(deck, ncards);

        printf("Testing removeCard.\n");

    removeCard(deck, &ncards, 0);
    printf("\tThe deck after removing the first card: ");
    printDeck(deck, ncards);

下面是我运行编译后的程序后的输出：

     The deck after adding the ten of hearts: 
King of hearts
King of spades
King of diamonds
Queen of diamonds
ten of hearts
Testing removeCard.
    The deck after removing the first card: ten �?D
King of spades
King of diamonds
Queen of diamonds

这就像我想要的那样做。然而，红桃十没有正确打印。里面有??D？谁能解释我在这里出错的地方？

Answer 1

在 C 数组中从 0 开始，所以

    int x = *deckLength;
    deck[index] = deck[x];

是错的。数组的最后一个元素有arraySize - 1索引。

正确的代码应该是

card removeCard(card deck[], int * deckLength, int index){
        card removed = deck[index];
        int indexLast = *deckLength - 1;
        deck[index] = deck[indexLast];
        deck[indexLast] = removed;
        *deckLength -= 1;
        return removed;