C++ 对二进制文件进行排序

Question

我有一段无法编译的代码。

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <Windows.h>
#include <iomanip>
using namespace std;


int average (int n);

int main() 
{

string filename;

int i,j;
int n = 0;
int sum = 0;
int size = 4;
const int nameLength = 19;
const int maxRecords = 100;
int index[100];


int scores[maxRecords];
char names[maxRecords][nameLength];

int count = 0;

cout << "Enter binary data directory and file name: ";
getline (cin, filename);
// Open file for binary read-write access.
    ifstream fin(filename.c_str(), ios::binary);

if (!fin) {
cout << "Could not open " << filename << endl;
system("PAUSE");
return -1;
}

// Read data from the file.
while (
fin.read(names[count], sizeof(names[0]))
     && fin.read((char *) &scores[count], sizeof(scores[0]))
)
{

    count++;
    fin.ignore(); // skip the padding byte
}


// Display the data and close.
 cout << "Your file's data unsorted: " << endl;
cout << endl;
    cout << setw(10) << "Name" << setw(20) <<  "Test Score" << endl;

    for (i=0;i<n;i++){
            cout << setw(10) << names[i] << setw(20) << scores[i] << endl;
    }

            for (i=0;i<n;i++)
    {
            index[i]=i;
    }

    for (i=0;i<n;i++)
    {

            for (j=i+1;j<n;j++)
            {
                    int temp;
                    if (scores[index[i]] > scores[index[j]])
                    {
                            temp = index[i];
                            index[i] = index[j];
                            index[j] = temp;
                    }
            }
    }

    cout << "The average of the test scores in your file is:  " << average         (sum);

sum=sum+scores[i];


fin.close();
system("PAUSE");
return 0;
}

int average (int sum, int size)
{ 
return sum/size;
}

我收到一个编译错误，上面写着：fatal error LNK1120: 1 unresolved externals，我不知道为什么。还有一个问题是如何格式化，这样从原始二进制文件中读取的数据不会被篡改，然后输出并保存在一个新的编辑二进制文件中？

Answer 1

你像这样转发声明average：

int average (int n);

但你以这种方式实现平均：

int average (int n, int size);

如果您更新前向声明并在此处添加第二个参数：

cout << "The average of the test scores in your file is:  " << average(sum,size);

应该可以解决它。