C++练习题1-9

NO1、选出妃子、宫女和嬷嬷

其他要求：

• 超女用结构体表示
• 不要嵌套if
• 输入所有数据后再判断

#include <iostream>
#include <string>

using namespace std;
struct CGirl {
   
    int age;
    int high;
    string sc;
    //c风格字符串 char sc[31];  字符串比较就要用 strcmp
    bool yz;
};

int main() {
   
    CGirl g;
    cout << "请依次输入年龄、身高(cm)、身材(火辣/普通)、颜值(漂亮/一般)：";
    string stringYz{
   0};
    cin >> g.age >> g.high >> g.sc >> stringYz;
    g.yz = (stringYz == "漂亮") ? true : false;
    if ((g.age >= 18 && g.age <= 25) && (g.high >= 165 && g.high <= 178) && (g.sc == "火辣") && g.yz)
        cout << "妃子" << endl;
    else if ((g.age >= 18 && g.age <= 30) && (g.high >= 160 && g.high < 165) && (g.sc == "火辣" || g.sc == "普通") &&
             g.yz)
        cout << "宫女" << endl;
    else if ((g.age >= 35 && g.age <= 40) && (g.high >= 155 && g.high < 165) && (g.sc == "飞机场" || g.sc == "普通") &&
             (!g.yz))
        cout << "嬷嬷" << endl;
/*    else
        cout<<"落选"<<endl;*/
    return 0;
}

No2、根据数字判断月份

其他要求：

• ifelse或者switchcase实现
• 字符串数组实现（C/C++）

#include <iostream>

int main() {
   
    int mouth = -1;
    std::cout << "请输入月份（1-12）：";
    std::cin >> mouth;
    /*switch (mouth) {
        case 1:
            std::cout<<"January"<<std::endl;
            break;
        case 2:
            std::cout<<"February"<<std::endl;
            break;
        case 3:
            std::cout<<"March"<<std::endl;
            break;
        case 4:
            std::cout<<"April"<<std::endl;
            break;
        case 5:
            std::cout<<"May"<<std::endl;
            break;
        case 6:
            std::cout<<"June"<<std::endl;
            break;
        case 7:
            std::cout<<"July"<<std::endl;
            break;
        case 8:
            std::cout<<"August"<<std::endl;
            break;
        case 9:
            std::cout<<"September"<<std::endl;
            break;
        case 10:
            std::cout<<"October"<<std::endl;
            break;
        case 11:
            std::cout<<"November"<<std::endl;
            break;
        case 12:
            std::cout<<"December"<<std::endl;
            break;
        default:
            std::cout<<"输入错误"<<std::endl;
    }*/

    //效率高于ifelse 和 switch case
    char months[12][10] = {
   "January","February","March","April","May","June","July"
    ,"August","September","October","November","December"};

    if (mouth>=1&&mouth<=12)
        std::cout<<months[mouth-1]<<std::endl;
    else
        std::cout<<"输出错误"<<std::endl;
}

No3、循环计数

#include <iostream>

int main() {
   
    int sum = 0;
    int i = 0;
    while (i <= 100) {
   
        sum += i++;
    }
    std::cout << "1-100之间的和为" << sum << "\n";

    int num{
   0};
    int sumF{
   0};;
    for (;sumF <= 5000;) {
   
        std::cin>>num;
        sumF+=num;
    }
    std::cout << "输入的和为" << sumF << "\n";
    

    return 0;
}

No4、循环选数

/**
  ******************************************************************************
  * @file           : demo4.cpp
  * @author         : DELL
  * @brief          : None
  * @attention      : None
  * @date           : 2024-01-25
  ******************************************************************************
  */
#include <iostream>

int main() {
   
    int num{
   0}, count{
   0}, sum{
   0};
    while (std::cin >> num) {
   
        if (!num)break;
        if (num < 1 || num > 100)
            continue;
        count++;
        sum += num;
    }
    std::cout << "符合条件个数：" << count << "--" << "它们的和：" << sum << "\n";


    int n{
   1};
    //取余数
    while (n <= 100) {
   
        if (n % 5 == 0)
            std::cout << n << " ";
        ++n;
    }
    std::cout << "\n";
    //另外一种写法
    n = 5;
    while (n <= 100) {
   
        std::cout << n << " ";
        n += 5;
    }
    return 0;
}

No5、玩转字符

//ASCII A->65 Z->90   a->97  z->122
void printLastChar(char &&c) {
   
    if (!((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))) {
   
        std::cout << "输入不合规" << "\n";
        return;
    }
    if (c == 'Z' || c == 'z') {
   
        std::cout << c << "的后面没有字符" << "\n";
        return;
    }
    std::cout << c << "后面的字符是：" << char(c + 1) << std::endl;

}

int ctoi(const char ch) {
   
    if (ch < '0' || ch > '9') {
   
        std::cout << "参数不合规" << std::endl;
        return -1;
    }
    return int(ch - 48);
}

No6、计算字符串长度

其他要求

• 封装成一个函数
• for循环+数组表示法+临时变量
• while+指针表示+临时变量
• 不用临时变量->递归

int len(char *c) {
   
    //1、for循环+临时变量+数组表示法
    /*int len{0};
    for (; c[len] != '\0'; ++len);
    return len;*/

    //2、while循环+临时变量+指针表示法
    /*char *p = c;
    int len{0};
    while (*p++)
        ++len;
    return len;*/

    //3、递归思路+不采用临时变量
    //递归开销大于循环）（
    if (*c == '\0')return 0;//中止条件
    c++;//指针后移
    return len(c) + 1;//后移之后的长度+1=本来的长度
    //递归中我们可以把下一层当作已知参数，比如
}

No7、显示字符串中的字符

void printStr(const char *c, bool isSequence = true) {
   
    int len = strlen(c);
    if (isSequence) {
   
        for (int i = 0; i < len; ++i) {
   
            std::cout << c[i] << " ";
        }
    } else {
   
        for (int i = len - 1; i >= 0; --i) {
   
            std::cout << c[i] << " ";
        }
    }
    std::cout << std::endl;
}

No8、字符串反转

//使用另外一个字符串
char *reverse(const char *str){
   
    char *newStr = new char[30];
    int len = ::strlen(str);
    ::memset(newStr,0, sizeof(newStr));
    for (int i = 0,j=len-1; i < len;)
        newStr[i++] = str[j--];
    return newStr;
}

//原地反转
void reserveS(char *str){
   
    //abc   d
    int len = ::strlen(str);
    int n = len/2;
    for (int i = 0; i < n; ++i) {
   
        char tmp = str[i];
        str[i] = str[len-i-1];
        str[len-i-1] = tmp;
    }
}

No9、二维数组的应用

任务一

    double weights[3][4];
    ::memset(weights,0, sizeof(weights));
    double total{
   0};
    for (int i = 0; i < 3; ++i) {
   
        double sum{
   0};
        for (int j = 0; j < 4; ++j) {
   
            double weight{
   0};
            cout<<"请输入第"<<i+1<<"组第"<<j+1<<"个超女的体重：";
            cin>>weight;
            weights[i][j] = weight;
            sum+=weight;
        }
        total+= sum;
        cout<<"第"<<i+1<<"小组超女的平均体重："<<sum/4<<"\n";
    }
    cout<<"所有小组超女的平均体重："<<total/12<<endl;

任务二

    char names[3][11];
    ::memset(names,0, sizeof(names));
    for (int i = 0; i < 3; ++i) {
   
        cout<<"请输入超女姓名：";
        cin>>names[i];
    }
    for (int i = 0; i < 3; ++i) {
   
        cout<<"表白："<<names[i]<<"\n";
    }