Question

我有一个user_get_movement_index函数，提示用户输入0到8的位置作为井字游戏的一部分。

此移动索引传递给is_position_empty，在此确定移动索引是无效还是已经采用移动索引，两者都显示错误消息并返回false以触发user_get_movement_index的递归。

当输入两次相同的数字时，函数正确循环，并且当输入任何其他数字但是为0时，其行为与预期一致。

问题是当输入0时会导致无效位置错误消息的循环。我不明白它是如何从is_position_empty中循环的。如何在每个循环中不提示用户输入？为什么0导致这个循环？

是因为我们正在比较0＆lt; is_position_empty中的0是什么？

我是C新手和堆栈溢出所以请原谅我的格式化，理解和可怕的代码。

//--------------------------------------------------
// 05. FUNCTION my_getchar (IMPLEMENTED)
//--------------------------------------------------
char my_get_char() {
//1. We create the variable to be returned
char res = ' ';

//2. We create an extra variable to consume any other characters entered until a return is pressed
boolean line_consumed = False;
char dummy_char = ' ';

//3. We consume the first char entered, i.e., the one we are interested at
res = getchar();

//4. While still there are remaining characters
while (line_consumed == False) {
    //4.1. We consume the next character
    dummy_char = getchar();

    //4.2. If the new character is the end of line one, we can ensure we have consumed the entire line.
    if (dummy_char == '\n')
        line_consumed = True;
}

//5. We return res
return res;
}

//------------------------------------
//  06. FUNCTION is_position_empty 
//------------------------------------
boolean is_position_empty(game* g, int pos) {
//1. We create the variable to be returned
boolean res = False;

//2. We check if the index is a valid one and if the board is empty at that index.
//If it is valid and free, we return True. 
//Otherwise, we return False and write a warning message.
int row= pos/3;
int column = pos%3;

if (pos<0 || pos>8){
    printf("\t Invalid Position. Try again!\n\n");
    return res;
}
else if (g->board[row][column]=='X' || g->board[row][column]=='O'){
    printf("\t This postion is already busy. Try Again!\n\n");
    return res;
}
else{

    res=True;
    return res;
}

}

//---------------------------------------
//  07. FUNCTION user_get_movement_index 
//---------------------------------------
int user_get_movement_index(game* g) {

//2. We create a boolean variable to control that we have received a valid movement index. 
boolean validMove=False;

//3. We create a char variable to control the index we are receiving by keyboard.
char indexChar;
int indexInt;

//We print a message asking for a new movement. 
printf("         Enter a position 0 to 8: ");

//We call to my_get_char to get the index and we convert it to an integer. 
indexChar=my_get_char();
indexInt=indexChar-'0';

//We call to is_position_empty to check that the index is a valid one.
validMove=is_position_empty(g, indexInt);

  if (validMove==True)
      return indexInt;
  else
      return user_get_movement_index(g);
}

正确工作

循环

我的boolean定义如下：

enum Bool { False, True };
typedef enum Bool boolean;

当我将矩阵的所有元素初始化为“a”时，问题仍然存在。输入有效移动时，将调用process_movement函数，并将板的相应元素初始化为“X”或“O”。

char mark;

if (g->status==1)
    mark='X';
else
    mark='O';

int row = pos/3;
int column = pos%3;

g->board[row][column]=mark;

通过在is_position中添加一个额外的printf，我可以告诉整个函数是循环的，但它似乎没有退出is_position_empty，因为它返回到user_get_movement的函数中的printf没有被打印。这怎么可能？在user_get_movement中只有一个循环而在is_position_empty中只有一个循环，并且只有0的循环？

Answer 1

以下提议的代码：

缺少main()函数
缺少确定是否有获胜者以及谁赢了的功能
缺少game
没有任何意外的循环
避免因递归而导致的问题。功能

现在建议的代码：

#include <stdio.h>   // getchar()
#include <stdbool.h> // bool, true, false
#include <ctype.h>   // isdigit()

// prototypes
int my_get_char( void );
bool is_position_empty(game* g, int pos);
int user_get_movement_index(game* g);


//--------------------------------------------------
// 05. FUNCTION my_getchar (IMPLEMENTED)
//--------------------------------------------------
int my_get_char()
{
    //1. We create the variable to be returned

    //3. We consume the first char entered, i.e., the one we are interested at
    int res = getchar();

    //4. While still there are remaining characters
    while ( '\n' != getchar() );

    //5. We return res
    return res;
}


//------------------------------------
//  06. FUNCTION is_position_empty
//------------------------------------
bool is_position_empty(game* g, int pos)
{
    //2. We check if the index is a valid one and if the board is empty at that index.
    //If it is valid and free, we return True.
    //Otherwise, we return False and write a warning message.
    int row= pos/3; = 0
    int column = pos%3; = 0

    if (pos<0 || pos>8)
    {
        printf("\t Invalid Position. Try again!\n\n");
        return false;
    }

    else if (g->board[row][column]=='X' || g->board[row][column]=='O')
    {
        printf("\t This postion is already busy. Try Again!\n\n");
        return false;
    }

    return true;
}


//---------------------------------------
//  07. FUNCTION user_get_movement_index
//---------------------------------------
int user_get_movement_index(game* g)
{
    //3. We create a char variable to control the index we are receiving by keyboard.
    int indexInt;

    do
    {
        //We print a message asking for a new movement.
        printf("         Enter a position 0 to 8: ");

        //We call to my_get_char to get the index and we convert it to an integer.
        indexInt = my_get_char();
        if( isdigit( indexInt ) )
        {
            indexInt -= '0';
        }

        else
        {
            printf( "entry was not in the inclusive range: 0...8\n" );
            continue;
        }

        //We call to is_position_empty to check that the index is a valid one.
    } while( !is_position_empty(g, indexInt) );

    return indexInt;
}

输入零时的函数循环

1 个答案: