?? set.cpp
字號:
#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
int ReadFile(char *filename)
{
int data;
ifstream input(filename, ios::nocreate);
if(input.fail())
{
cerr << "error opening file input\n";
return NULL;
}
input >> data;
return data;
input.close();
}
void WriteFile(char *filename, unsigned long x)
{
ofstream output(filename, ios::trunc);
if(output.fail())
{
cerr << "error opening file output\n";
return;
}
output << x;
output.close();
}
unsigned long set(int n)
{
unsigned long res=0;
unsigned long *buf;
buf = new unsigned long [(int)n/2];
for(int i=0; i<=n/2; i++)
{
buf[i] = 1;
for(int j=1; j<=i/2; j++)
buf[i] += buf[j];
res += buf[i];
}
return res;
}
void main()
{
int input;
if(ReadFile("set().in.txt") == NULL)
{
cout << "set().in.txt不存在!" << endl;
getchar();
return;
}
input = ReadFile("set().in.txt");
cout << " n的值為 " << input << endl;
if(input > 1000)
{
cout << "數(shù)字應(yīng)在1--1000之間!(按Enter鍵退出)" << endl;
getchar();
return;
}
unsigned long sum;
sum = set(input);
cout << "其元素個數(shù)為 " << sum << endl;
WriteFile("set().out.txt", sum);
cout << "結(jié)果已寫入set().out.txt文件!" << endl;
cout << "(按Enter鍵退出!)" << endl;
getchar();
}
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