c - 功能有一半时间失败

Question

我为我的项目编写了一个随机路径生成器，当它工作时，它会按预期工作。然而它只是有时有效。

在我的主函数中，我有一个简单的 switch 语句来调用该项目的三个任务。

while(Continue)
{

switch(Example_number)
    {
    default: printf("No such program exists.\n");
             break;
    case 1:  path();
             break;
    case 2:  Caesar_cipher();
             break;
    case 3:  anagram();
             break;
    }

    printf("Would you like to test another?(Y/N)\n");
    scanf("\n%c",&ch);
    if(ch == 'Y' || ch == 'y')
    {
        NULL;
    }
    else
    {
        Continue = false;
    }
}

当您输入 1 时，它会调用此函数，该函数会创建一个数组并调用其他两个函数。

void path(void)
{
    //Creates the array walk.
    char walk[10][10] = {{'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'},
                         {'.','.','.','.','.','.','.','.','.','.'}};

//Creates a randomly generated path to travel along walk.
generate_path(walk);
print_array(walk);
}

生成路径的函数。

void generate_path(char walk[10][10])
{
int move_n = 0;
int row, column, i;
const char alph[] = {'B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
//Array that holds all previous data.
int move[3][25] = {0};
bool block = false;

//Allows for a random variable.
srand((unsigned) time(NULL));

row = rand() % 10;
column = rand() % 10;

while(!block)
{
    walk[row][column] = 'A';
    for(i = 0; i < 25; i++)
    {
        //goto comes here
        restart:
        move_n = rand() % move_dir;
        //If space is open continue the alph array one row below.
        if(move_n == 0 && walk[row+1][column] == '.' && row+1 < 10)
        {
            row += 1;
            move[0][i] = i;
            move[1][i] = row;
            move[2][i] = column;
            walk[row][column] = alph[i];
        }
        else if(move_n == 1 && walk[row][column+1] == '.' && column+1 < 10) //If space is open continue the alph array one column to the right. 
        {
            column += 1;
            move[0][i] = i;
            move[1][i] = row;
            move[2][i] = column;
            walk[row][column] = alph[i];
        }
        else if(move_n == 2 && walk[row-1][column] == '.' && row-1 >= 0) //If space is open continue the alph array one row above.
        {
            row -= 1;
            move[0][i] = i;
            move[1][i] = row;
            move[2][i] = column;
            walk[row][column] = alph[i];
        }
        else if(move_n == 3 && walk[row][column-1] == '.' && column-1 >= 0) //If space is open continue the alph array one column to the left.      
        {
            column -= 1;
            move[0][i] = i;
            move[1][i] = row;
            move[2][i] = column;
            walk[row][column] = alph[i];
        }
        else if((walk[row][column-1] == '.') || (walk[row-1][column] == '.') || (walk[row][column+1] == '.') || (walk[row+1][column] == '.')) 
        {
            if(i == 25)
                break;
            goto restart;
        }
        else
        {
            //Resets data to point such that the path can continue.
            row = move[1][i-1];
            column = move[2][i-1];
            i--;
            walk[row][column] = '.';
        }
    }
    block = true;
}
}

以及打印数组函数。

void print_array(char walk[10][10])
{
int i = 0;
int k = 0;
for(i = 0; i < 10; i++)
{
    for(k = 0; k < 10; k++)
    {
        printf(" %c", walk[i][k]); 
    }
    printf("\n");
}
}

但由于某种原因，在 switch 语句中输入 1 时，它有时只能起作用。每次调用任何其他函数都可以完美地工作。

Answer 1

您的问题很可能出在generate_path() 中的if 语句上。

您访问 walk[row+1][column]、walk[row][column+1] 等。row 和 column 是用 rand()%10 生成的。因此，在某个时刻，row 和 column 值可以是 0 或 9访问索引row-1 column+1等，它将访问数组边界之外，这可能会导致各种问题。