c++ - 指针运算和冒泡排序 (C++)

Question

我似乎无法弄清楚我做错了什么。我今天在类里面做了笔记，但不幸的是我的 OneNote 崩溃了，把我今天的所有笔记都删除了。我知道我缺少一些东西，但我无法弄清楚。我翻遍了我的课本，甚至在网上看了一个多小时。我似乎找不到任何有用的东西。

我知道我的错误可能是我在 if 或 set 变量语句中使用了 charPtr++，但我不记得如何做到这一点。如何检查一个元素是否小于另一个元素？

我们应该使用指针算术来编写 10 个元素的降序冒泡排序。有人可以解释我做错了什么以及为什么我的程序只输出原始数组吗？谢谢!

我们也不能使用括号或偏移符号。

#include <iostream>
#include <fstream>

using namespace std;

int main() {

    // DRIVER PROGRAM

    char *characters, *charPtr = nullptr; // Array or undefined size.
    fstream fs; // file stream for file arithmetic


    fs.open("array.txt", ios::in); // Open the file
    char currentChar; // Used to check if the file can still be read.
    int counter = 0; // Counter to check how many elements are in the array.
    while (fs >> currentChar) { // While data can be put into counter, continue...

            counter++; // Add one to counter

    }

    characters = new char[counter]; // Sets size of array.
    charPtr = characters;

    fs.clear(); // Clears eof flag.
    fs.seekg(0, ios::beg); // Sets pointer back to the beginning. CHECK IF YOU CAN REMOVE THIS LINE AND THE ONE ABOVE.

    for (int i = 0; i < counter; i++) { // While less than the size of array.

        fs >> charPtr; // Write to charPtr
        cout << *charPtr << " "; // Output array.
        charPtr++; // Move to next element

    }

    fs.close(); // Close file
    putchar('\n'); // Output newline efficiently.
    charPtr = characters;

    // BUBBLE SORT

    bool swapChar;
    char temp;

    do {

        swapChar = false;


        for(int count = 0; count < (counter - 1); count++) {

            if (*(charPtr) < *(charPtr++)) { // If character at 0 is less than the character at 1

                temp = *(charPtr); // Set temp to character at 0
                *(charPtr) = *(charPtr++); // set character at 0 to character at 1
                *(charPtr++) = temp; // set character at 1 to temp
                swapChar = true; // set swap to true 
                cout << *charPtr << " "; // output current swap
                charPtr++; // add 1 to charPtr
            }

        }
    } while (swapChar == true);

}

Answer 1

请记住 charPtr++ 会自增。在下面的代码块中，您进行了 4 次递增，而您本以为只有一次。您应该将其替换为 *(charPtr+1)。

if (*(charPtr) < *(charPtr++)) { // If character at 0 is less than the character at 1 
    temp = *(charPtr); // Set temp to character at 0
    *(charPtr) = *(charPtr++); // set character at 0 to character at 1 
    *(charPtr++) = temp; // set character at 1 to temp 
    swapChar = true; // set swap to true 
    cout << *charPtr << " "; // output current swap
    charPtr++; // add 1 to charPtr 
}