c - 在 C 中写入数组的数组并显示数组的数组中的单独实体

Question

我正在编写一个基本上有 10 条街道的代码，在每条街道中，用户都会被要求提供房屋数量以及每间房屋中的 child 数量。但是，当我尝试显示街道数量时，房屋数量有效，但房屋中的 child 数量却不起作用。我还想知道如何添加街道上 child 的数量，例如街道 1 总共有 10 个 child (我真的不知道如何执行这部分)。我认为问题出在我的 for 循环中，但我不完全确定问题是什么。代码如下所示:

int main()
{

int i=0;
int j=0;
int streets[10];
int houses=0;
int KidsInStreets[houses];
for (i=0;i<10;i++)
{
    printf("How many houses are there in street %d:\n", i+1);
    scanf("%d",&houses);
    for (j=0;j<houses;j++)
    {
        printf("How many kids are there in house number %d, in street number %d:\n", j+1, i+1);
        scanf("%d", &KidsInStreets[j]);
    }
}
for (i=0;i<10;i++)
{
    for (j=0;j<houses;j++)
    {
        printf("Street:%d House:%d Kids:%d\n", i+1, j+1, KidsInStreets[j]);//Kids in street output and houses output have bugs, such as all the houses in the street need to be displayed, and the kids thing is just not working
    }
}
return 0;

}

Answer 1

一个问题是，当您执行 int KidsInStreets[houses]; 时，houses 为零。但真正的问题是，您只有一个数组，但每条街道都需要一个数组。

尝试如下:

int* streets[10];   // Notice *
int houses=0;
for (i=0;i<10;i++)
{
    printf("How many houses are there in street %d:\n", i+1);
    scanf("%d",&houses);
    streets[i] = malloc(houses * sizeof(int)); // Allocate array
    for (j=0;j<houses;j++)
    {
        printf("How many kids are there in house number %d, in street number %d:\n", j+1, i+1);
        scanf("%d", &streets[i][j]);
    }
}

但问题是，现在你不知道每条街道有多少栋房子。所以您需要保存该信息。为此，您可以创建一个结构体或一个额外的数组。

额外的数组不是那么优雅，但非常简单:

int* streets[10];   // Notice *
int houses_in_street[10];
int houses=0;
for (i=0;i<10;i++)
{
    printf("How many houses are there in street %d:\n", i+1);
    scanf("%d",&houses);
    streets[i] = malloc(houses * sizeof(int)); // Allocate array
    houses_in_street[i] = houses;
    for (j=0;j<houses;j++)
    {
        printf("How many kids are there in house number %d, in street number %d:\n", j+1, i+1);
        scanf("%d", &streets[i][j]);
    }
}


for (i=0;i<10;i++)
{
    for (j=0;j<houses_in_street[i];j++)
    {
        printf("Street:%d House:%d Kids:%d\n", i+1, j+1, streets[i][j]);
    }
}

更好的解决方案是这样的结构:

struct street {
    int number;
    int houses;
    int* kids_in_house;
};

// use it like
struct street streets[10];