实验3

实验任务1

#include <stdio.h>

char score_to_grade(int score);
int main() {
    int score;
    char grade;

    while (scanf_s("%d", &score) != EOF) {
        grade = score_to_grade(score);
        printf("分数: %d, 等级: %c\n\n", score, grade);
    }

    return 0;
}
char score_to_grade(int score) {
    char ans;

    switch (score / 10) {
    case 10:
    case 9:   ans = 'A'; break;
    case 8:   ans = 'B'; break;
    case 7:   ans = 'C'; break;
    case 6:   ans = 'D'; break;
    default:  ans = 'E';
    }

    return ans;
}

 

问题1：将分数转化为等级；整型；字符型

问题2：case会穿透；字符用单引号

实验任务2

#include <stdio.h>

int sum_digits(int n);

int main() {
    int n;
    int ans;

    while (printf("Enter n: "), scanf_s("%d", &n) != EOF) {
        ans = sum_digits(n);
        printf("n = %d, ans = %d\n\n", n, ans);
    }

    return 0;
}

int sum_digits(int n) {
    int ans = 0;

    while (n != 0) {
        ans += n % 10;
        n /= 10;
    }

    return ans;
}

 

 

实验任务3

#include <stdio.h>

int power(int x, int n);

int main() {
    int x, n;
    int ans;

    while (printf("Enter x and n: "), scanf_s("%d%d", &x, &n) != EOF) {
        ans = power(x, n);
        printf("n = %d, ans = %d\n\n", n, ans);
    }

    return 0;
}
int power(int x, int n) {
    int t;

    if (n == 0)
        return 1;
    else if (n % 2)
        return x * power(x, n - 1);
    else {
        t = power(x, n / 2);
        return t * t;
    }
}

问题1：计算x的n次方

 

实验任务4

#include<stdio.h>

int is_prime(int n) {
    if (n <= 1)
        return 0;
    for (int i = 2; i < n; i++) {
        if (n % i == 0)
            return 0;
    }
    return 1;
}
int main() {
    int count = 0;
    printf("100以内的孪生素数：\n");
    for (int n = 2; n <= 98; n++) {
        if (is_prime(n) && is_prime(n + 2)) {
            printf("%d %d\n", n, n + 2);
            count++;
        }
    }
    printf("100以内的孪生素数共有：%d\n", count);
    return 0;
}

 

实验任务5

递归

#include <stdio.h>
int func(int n, int m);   // 函数声明

int main() {
    int n, m;
    int ans;

    while (scanf_s("%d%d", &n, &m) != EOF) {
        ans = func(n, m);   // 函数调用
        printf("n = %d, m = %d, ans = %d\n\n", n, m, ans);
    }

    return 0;
}
int func(int n, int m) {
    if (n==m || m==0) {
        return 1;
    }
    else {
        return func(n-1, m) + func(n-1, m-1);
    }
}

迭代

#include<stdio.h>
int func(int n, int m) {
    int ans, i, j, a = 1, b = 1;
    if (n < m)
        ans = 0;
    else {
        for (i = 1; i <= m; i++)
            a *= i;
        for (j = n; j > n - m; j--)
            b *= j;
        ans = b / a;
    }
    return ans;
}
int main() {
    int n, m;
    int ans;
    while (scanf_s("%d%d", &n, &m) != EOF) {
        ans = func(n, m);
        printf("n=%d,m=%d,ans=%d\n\n", n, m, ans);
    }
    return 0;
}

 

实验任务6

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int gcd(int a, int b, int c);
int main() {
    int a, b, c;
    int ans;

    while (scanf("%d%d%d", &a, &b, &c) != EOF) {
        ans = gcd(a, b, c); // 函数调用
        printf("最大公约数: %d\n\n", ans);
    }
    return 0;
}
int gcd(int x, int y, int z) {
    int m,n,i;
    m =(x > y ? x : y);
    i = (m > z ? m: z);
    for (; i > 0; i--) {
        if (x % i == 0 && y % i == 0 && z % i == 0) {
            n = i;
            break;
        }
    }
    return n;
}

实验任务7

#include <stdio.h>
#include <stdlib.h>
void print_charman(int a);
int main() {
    int n;
    printf("Enter n: ");
    scanf_s("%d", &n);
    print_charman(n);
    return 0;
}
void print_charman(int a) {
    int count = 0;
    int x = 0;

    for (int I = 2 * a - 1; I > 0; I = I - 2) {
        for (int i2 = 1; i2 <= x; i2++) {
            printf(" ");
        }
        for (int i1 = 1; i1 <= I; i1++) {
            printf("  O  ");
        }
        printf("\n");

        for (int i2 = 1; i2 <= x; i2++) {
            printf(" ");
        }
        for (int i1 = 1; i1 <= I; i1++) {
            printf(" <H> ");
        }
        printf("\n");

        for (int i2 = 1; i2 <= x; i2++) {
            printf(" ");
        }
        for (int i1 = 1; i1 <= I; i1++) {
            printf(" I I ");
        }
        printf("\n");

        count++;
        x += 5;
    }

}