4 、while循环

一、while 循环
二、do-while 循环

一、`while` 循环🧀

while () {
}

数位判断

int main() {
    int a;
    int digits = 0;


    printf("Enter a number:");
    scanf("%d", &a);
    // 以下两句写在循环外是为了处理“0”的情况，否则将会输出0位数
    digits++;
    a = a / 10;

    while (a > 0) {
        digits++;
        a = a / 10;
    }
    printf("%d", digits);

    return 0;
}
// 电脑中有数位限制，太大的数字不行

debug

测试程序常使用边界数据 ,如有效范围两端的数据、特殊的倍数等
循环体内要有改变条件的机会 → 不然会变成死循环

二、`do-while` 循环🧀

do {
} while ();

`do-while` 循环	`while` 循环
先进入循环再判断条件	先判断条件再进入循环

int main() {
    int a;
    int digits = 0;
    printf("Enter a number:");
    scanf("%d\n", a);

    do {
        x = x / 10;
        digits++;
    } while (a > 0);

    return 0;
}

猜数字

#include <bits/stdc++.h>
using namespace std;

int generateRandom() {
    srand(time(NULL));
    return rand() % 100;
}

int main() {
    int num = generateRandom();
    int guess;
    cout << "Guess a number between 0 and 99: ";

    bool flag = false;
    while (flag == false) {
        cin >> guess;
        if (guess == num) {
            cout << "Congratulations! You guessed the number correctly." << endl;
            flag = true;
        } else if (guess < num) {
            cout << "The number you guessed is too low. Try again: ";
        } else {
            cout << "The number you guessed is too high. Try again: ";
        }
    }
}

算平均数

#include <bits/stdc++.h>
int main() {
    int x;
    int sum = 0;
    int count = 0;
    int number[100];

    scanf("%d", &x);
    while (x != -1) {
        number[count] = x;
        sum = sum + x;
        count++;
        scanf("%d", &x);
    }
    if (count > 0) {
        printf("The average of all numbers is %f\n", 1.0 * sum / count);
        int i;
        printf("%d\t", number[i]);
        for (i = 0; i < count; i++) {
            if (number[i] > sum / count) {
                printf("%d\n", number[i]);
            }
        }
    }

    return 0;
}

整数逆序分解

要分解一个整数的各个位上的数字并进行计算，可以按照以下步骤进行：

进行 % 10 操作，得到个位数。
/ 10 操作，去掉个位数。
重复上述两个步骤，直到整数变为0。

#include <bits/stdc++.h>
int main() {
    int x;
    int reverse = 0;
    int digits = 0;
    printf("Enter a number:");
    scanf("%d", &x);

    while (x > 0) {
        digits = x % 10;
        x = x / 10;
        reverse = reverse * 10 + digits;
        printf("%d,%d,%d\n", digits, x, reverse); // 测试语句
    }
    printf("The reverse is: %d", reverse); // 逆序输出
    return 0;
}

4 、while循环

一、while 循环🧀

二、do-while 循环🧀

一、`while` 循环🧀

二、`do-while` 循环🧀