问题描述
我的指导是建立一个动态数组以容纳数组中确切数量的值,然后将文件中的值读入数组。
将值放入数组后,请使用冒泡排序对其进行排序。然后输出数组中的最低和最高值。
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很遗憾,我不允许使用向量。 :(
这是我编写的代码,感谢您的帮助!
#include <iostream>
#include <fstream>
using namespace std;
void bubbleSort(int[],int);
void printArray(int[],int);
int main()
{
// open the file
ifstream file;
file.open("4253512.txt");
// program reads file and counts how many numbers in array.
cout << "Reading from the file..." << endl;
float i;
int nElements = 0;
while (file >> i) // checks whether it's good or not
{
nElements++;
}
cout << "The amount of numbers in the file are: " << nElements << endl;
//put numbers into dynamic array
int *arr = new int[nElements];
for (i = 0; i < nElements; i++)
{
file >> arr[nElements];
}
// bubble sort the numbers
bubbleSort(arr,nElements);
// printing out the highest and lowest values
printArray(arr,nElements);
delete[] arr;
file.close();
return 0;
}
void bubbleSort(int arr[],int n)
{
for(int j = 0; j < n; j++)
{
for(int i = j + 1; i < n; i++)
{
if(arr[j] > arr[i]) // swap if bigger
swap(arr[j],arr[i]);
}
}
}
void printArray(int arr[],int n)
{
cout << "The lowest value of the array is " << arr[0] <<
" and the highest value is " << arr[n] << endl;
}
构建和运行btw时没有运行时错误。
解决方法
代码很少出现问题。 不会进入文件流的开头,而是使用nElements而不是i将值传递给数组,并访问arr [n]而不是n-1。
#include <iostream>
#include <fstream>
using namespace std;
void bubbleSort(int[],int);
void printArray(int[],int);
int main()
{
// open the file
ifstream file;
file.open("4253512.txt");
// program reads file and counts how many numbers in array.
cout << "Reading from the file..." << endl;
float i;
int nElements = 0;
while (file >> i) // checks whether it's good or not
{
nElements++;
}
cout << "The amount of numbers in the file are: " << nElements << endl;
//seek to beginning of file stream
file.clear();
file.seekg(0);
//put numbers into dynamic array
int* arr = new int[nElements];
for (i = 0; i < nElements; i++)
{
//pass to i not nElements
file >> arr[(int)i];
}
// bubble sort the numbers
bubbleSort(arr,nElements);
// printing out the highest and lowest values
printArray(arr,nElements);
delete[] arr;
file.close();
return 0;
}
void bubbleSort(int arr[],int n)
{
for (int j = 0; j < n; j++)
{
for (int i = j + 1; i < n; i++)
{
if (arr[j] > arr[i]) // swap if bigger
swap(arr[j],arr[i]);
}
}
}
void printArray(int arr[],int n)
{
cout << "The lowest value of the array is " << arr[0] <<
// n-1 not n
" and the highest value is " << arr[n-1] << endl;
}