源程序：
#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;
const int MAX_NUM = 1000;
class CStudent
{
public:
char id[11];
char name[21];
int score;
}stu[MAX_NUM];
int MyCompare(const void *el, const void *e2)
{
return(*(CStudent *)el).score - (*(CStudent *)e2).score;
}
int main()
{
ifstream srcFile("c:\tmp\score.txt", ios::in);
if (!srcFile)
{
cout << "opening source file error." << endl;
return 0;
}
ofstream destFile("c:\tmp\out.txt", ios::out);
if (!destFile)
{
srcFile.close();
cout << "opening destination file error." << endl;
return 0;
}
int n = 0;
cout << "排序前：
";
while (srcFile >> stu[n].id >> stu[n].name >> stu[n].score)
{
cout << stu[n].id << "" << stu[n].name << "" << stu[n].score << endl;
n++;
}
qsort(stu, n, sizeof(CStudent), MyCompare);
cout << "排序后:
";
for (int i = 0; i<n; ++i)
{
cout << stu[i].id << "" << stu[i].name << "" << stu[i].score << endl;
destFile << stu[i].id << "" << stu[i].name << "" << stu[i].score << endl;
}
destFile.close();
srcFile.close();
system("pause");
return 0;
}
运行结果：
