Question

我正在尝试创建气泡排序算法，并且不断遇到错误。我在第一个for循环中经常遇到错误，它声称这是一个不合格的ID。我还遇到了一些错误，其中一个变量需要在for循环中再次声明类型，这会导致整个代码出现问题。

bubble-sort.cpp:12:1: error: expected unqualified-id before ‘for’
   12 | for (int hop=0; hop <= 10; hop++){
      | ^~~
bubble-sort.cpp:12:17: error: ‘hop’ does not name a type
   12 | for (int hop=0; hop <= 10; hop++){
      |                 ^~~
bubble-sort.cpp:12:28: error: ‘hop’ does not name a type
   12 | for (int hop=0; hop <= 10; hop++){
      |                            ^~~
bubble-sort.cpp:28:1: error: expected declaration before ‘}’ token
   28 | };
      | ^

我从这段代码中得到了这些错误。

#include <iostream>
using namespace std;

int array [5] = {19,3,90,1,9};

class BubSor {

public:

    int temp;
    for (int hop=0; hop <= 10; hop++){
        while (hope >=10 ){
            for (int j=0; j <=5; j++;){
                if (array[j]>array[j+1]){
                    array [j] = temp;
                    array [j+1] = array [j];
                    temp = array [j+1];
                }
            }
        }
    }
};
};

int main (){

    BubSor object;
    object  ;

    return 0;
}

Answer 1

可以帮助您改进原始代码的评论：

// avoid making global variables. Only constants that are used throughout your program should be made global.
//Also when making an array like this instead of using 5 do the following
// const int SIZE = 5;
// int array[SIZE] = {19,3,90,1,9};
// this way you can use the size later on
int array [5] = {19,3,90,1,9};

class BubSor {

public:
// you have to put this in a function
    int temp;
// bounding it by 10 is not correct because this number will change
// and you also the most passes you will ever have to make will be the size of the array
    for (int hop=0; hop <= 10; hop++){
// you do not need this while loop
// also hope should be hope
        while (hope >=10 ){
// this should be bound by the size of the array -1, because you are comparing to j + 1, otherwise you will go over the size of the array
            for (int j=0; j <=5; j++;){
                if (array[j]>array[j+1]){
                // here you should place it into temp instead
                    array [j] = temp;
                    // this should be done in reverse order
                    array [j+1] = array [j];
                    // swap the next line too
                    temp = array [j+1];
                }
            }
        }
    }
}; // you do not need the extra ; here
}; // this one is necessary because it is a class

int main (){
    BubSor object;
// here you need to call the function that is inside the class
    object  ;

    return 0;
}

我上面给出的建议的可能实现版本：


// no global variable array

class BubSor {

public:
// the code is wrapped in a reusable function called sort which takes
// as parameters an array and its size N
    void sort(int* array, const int N)
    {
        int temp;
        bool swapped = true; // if you haven't made any swaps then the array is already sorted
        // bound the for loop by the actual size of the array
        for (int hop = 0; hop < N && swapped; hop++) {
            swapped = false;
            // inner for loop goes only to the size -1 because
            // we are comparing j to j + 1, otherwise we go over the size
            // of the array
            for (int j = 0; j < N-1; j++) {
                // if unordered swap
                if (array[j] > array[j + 1]) {
                    temp = array[j + 1];
                    array[j + 1] = array[j];
                    array[j] = temp;
                    swapped = true;
                }
            }
        }
    }
};

int main() {

    // good practice to place it in a const
    const int N = 13;
    int arr[N] = { 19,3,1,2,3,11,10,9,3,4,90,1,9 };
    BubSor object;
    // use the sort function to sort the array
    object.sort(arr, N);
    // print the array to see if the function is working
    for (int x : arr)
    {
        cout << x << " ";
    }
    cout << "\n";
}

我找不到我的代码出了什么问题

1 个答案: