demo_4_file_txt_2.cpp

对于一个初涉VC＋＋的人来书

//****************************************************************
// 由键盘读入一行字符,将其中字母依次存在磁盘文件File1.txt中,
// 而后把它从磁盘文件读入程序,并将其中的小写字母改为大写字母,
// 再存入磁盘文件File2.txt中.
//****************************************************************
// 由显示器查看磁盘上ASCII文本文件File2.txt:
// 1. 直接用鼠标右键"打开方式-记事本"查看.
// 2. 用根目录"开始-程序-附件-DOS命令提示符"的DOS环境查看,
//    在文件的当前目录下用"type File2.txt"命令查看.
// 3. 编写一段程序查看.
//****************************************************************

# include <fstream.h>
# include <stdlib.h>

void save_to_file(char *filename)
{
	ofstream outfile(filename);

	if(!outfile)
	{
		cerr<<"open "<<filename<<" error!"<<endl;
		exit(1);
	}

	char c[80];

	cout<<"Please input a line of words:"<<endl;
	cin.getline(c,80);

	for(int i=0;c[i];i++)
	{
		if(c[i]>='a' && c[i]<='z' || c[i]>='A' && c[i]<='Z')
		{
			outfile<<c[i];
//			outfile.put(c[i]);
			cout<<c[i];
		}
	}
	cout<<endl;

	outfile.close();
}

void get_from_file(char *filename1,char *filename2)
{
	char ch;
	
//	ifstream infile(filename1,ios::in);
	ifstream infile(filename1,ios::in|ios::nocreate);
	
	if(!infile)
	{
		cerr<<"open "<<filename1<<" error!"<<endl;
		exit(1);
	}
	
	ofstream outfile(filename2);
	
	if(!outfile)
	{
		cerr<<"open "<<filename2<<" error!"<<endl;
		exit(1);
	}
	
//	while(infile.get(ch))
	while(infile>>ch)
	{
		if(ch>=97 && ch<=122)
			ch=ch-32;
//		outfile.put(ch);
		outfile<<ch;
		cout<<ch;
	}
	cout<<endl;

	infile.close();
	outfile.close();
}

void display_file(char *filename)
{
	ifstream infile(filename,ios::in|ios::nocreate);
	
	if(!infile)
	{
		cerr<<"open "<<filename<<" error!"<<endl;
		exit(1);
	}

	char ch;

	while(infile.get(ch))
		cout.put(ch);

	cout<<endl;

	infile.close();
}

int main()
{
	save_to_file("File1.txt");
	get_from_file("File1.txt","File2.txt");
	display_file("File2.txt");
	
	return 0;
}

/*
Please input a line of words:
I study C++ very hard.
IstudyCveryhard
ISTUDYCVERYHARD
ISTUDYCVERYHARD
Press any key to continue
*/