明解C语言入门篇（第8章练习题）

8.1

#define diff(x, y) ((x) - (y))

8.2

#define max(max(a, b), max(c, d)) ((max(a, b) > max(c, d)) ? (max(a, b)) : (max(c, d)))
#define max(max(max(a, b), c), d) ((max(max(a, b), c) > d) ? (max(max(a, b), c)) : (d))

8.3

#define swap(type, a, b) (int temp; temp = x; x = y; y = temp)

8.4

#include

#define NUMBER 5

void bsort(int a[], int n)
{
    int i, j;

    for (i = 0; i < n - 1; i++)
    {
        for (j = n - 1; j > i; j--)
        {
            if (a[j] > a[j - 1])
            {
                int temp = a[j];
                a[j] = a[j - 1];
                a[j - 1] = temp;
            }
        }
    }
}

int main(void)
{
    int i;
    int height[NUMBER];

    printf("请输入%d人的身高。\n", NUMBER);
    for (i = 0; i < NUMBER; i++)
    {
        printf("%2d号: ", i + 1);
        scanf("%d", &height[i]);
    }

    bsort(height, NUMBER);

    puts("按降序排列。");
    for (i = 0; i < NUMBER; i++)
    {
        printf("%2d号: %d\n", i + 1, height[i]);
    }

    return 0;
}

8.5

enum sex {man, woman};

enum time {spring, summer, autumn, winter};

8.6

#include

int main(void)
{
    int i, num;
    int sum = 1;

    printf("请输入一个整数: ");
    scanf("%d", &num);
    if (num > 0)
    {
        for (i = 1; i <= num; i++)
        {
            sum *= i;
        }
    }
    printf("%d的阶乘为%d。\n", num, sum);

    return 0;
}

8.7

#include

int combination(int n, int r)
{
    int c;

    if (r ==0 || n == r)
        c = 1;
    else if (r == 1)
        c = n;
    else
        c = combination(n - 1, r - 1) + combination(n - 1, r);

    return c;
}

int main(void)
{
    int n, r;

    printf("请输入所有不同的整数个数: ");
    scanf("%d", &n);
    printf("请输入取出的整数个数: ");
    scanf("%d", &r);
    printf("从%d个不同整数中取出%d个整数的组合数为%d。\n", n, r, combination(n, r));

    return 0;
}

8.8

#include

int gcd(int x, int y)
{
    int z;

    if (x != y)
    {
        if (x > y)
            x -= y;
        else
            y -= x;
        z = gcd(x, y);
    }
    else
        z = x;

    return z;
}

int main(void)
{
    int x, y;

    printf("请输入2个整数的值。\n");
    printf("1号: ");       scanf("%d", &x);
    printf("2号: ");       scanf("%d", &y);
    printf("2个整数的最大公约数为%d。", gcd(x, y));

    return 0;
}

8.9

#include

int main(void)
{
    int c, n1;
    n1 = 0;
    
    while ((c = getchar()) != EOF)
    {
        if (c == '\n')
            ++n1;
    }
    printf("该标准输入的行数为%d。\n", n1);
    
    return 0;
}

8.10

#include

int main(void)
{
    int i, ch;
    int cnt[10] = {0};

    while ((ch = getchar()) != EOF)
    {
        if (ch >= '0' && ch <= '9')
            cnt[ch - '0']++;
    }

    puts("数字字符的出现次数。");
    for (i = 0; i < 10; i++)
    {
        printf("'%d': ", i);
        while (cnt[i]--)
            putchar('*');
        putchar('\n');
    }

    return 0;
}