c++入门之文件读取

1 #include "iostream"
2 # include "fstream"
3 # include "cstdlib"
4 const int SIZE{ 60 };
5 int main()
6 {
7 using namespace std;
8 char filename[SIZE];
9 ifstream Infile;//定义一个输入流对象,等效于cin
10 cout <<"Enter name of data file:";
11 cin.getline(filename, SIZE);//从输入流中截取最大SIZE个字符的字符串作为文件名,遇到换行符\n也会终止
12 Infile.open(filename);//打开文件
13 if (!Infile.is_open())//文件打开成功返回1
14 {
15 cout <<"could not fine the file:" < endl;
16 exit(EXIT_FAILURE);//打开失败退出系统
17 }
18
19 double value;
20 double sum{ 0.0 };
21 int count{ 0 };
22
23 Infile >> value;//注意Infile 相当于cin
24 while (Infile.good())
25 {
26 &＃43;&＃43;count;
27 sum &＃43;&＃61; value;
28 Infile >> value;
29 }
30 if (Infile.eof())//eof判断是否读到文件末尾,读到末尾返回值为1.
31 cout <<"End of file readed.\n";
32 else if (Infile.fail())
33 cout <<"missing match" << endl;
34 else
35 cout <<"input for unknowm" << endl;
36 if (count &＃61;&＃61; 0)
37 cout <<"No data" << endl;
38 else
39 {
40 cout <<"sum is:" < endl;
41 cout <<"average is:" < endl;
42 }
43 Infile.close();
44 system("pause");
45 return 0;
46 }