C++文件的操作及小实验示例代码详解

//第一种
char buf[1024] = { 0 };
while (ifs >> buf) {
    cout << buf << endl;
}

//第二种
char buf[1024] = { 0 };
while (ifs.getline(buf, sizeof(buf))) {
	cout << buf << endl;
}

//第三种
string buf;
while (getline(ifs, buf)) {
	cout << buf << endl;
}

//第四种
char c;
while ((c = ifs.get()) != EOF) {//EOF： end of file
	cout << c;
}

#include<fstream>//文件的头文件
using namespace std;
int main()
{
	double a1[15], a2[11], a3[26];//分别对应三个文本文件的数组
	//对f1的操作
	//先创建一个流对象
	ofstream ofs1;
	//打开文件
	ofs1.open("f1.txt", ios::out);
	//写数据
	for (int i = 0; i < 15; i++) {
		a1[i] = (i + 1) * (i + 1) + 0.5;
		ofs1 << a1[i] << " ";
	}
	//关闭文件
	ofs1.close();
	//对f2的操作
	//与上方的代码相似
	ofstream ofs2;
	ofs2.open("f2.txt", ios::out);
	for (int i = 0; i < 10; i++) {
		a2[i] = (i + 1) * 10 + 0.5;
		ofs2 << a2[i] << " ";
	}
	a2[10] = 357.9;
	ofs2 << a2[10] << " ";
	ofs2.close();
	//对f3的操作
	//与上方类似
	int i = 0, j = 0, k = 0;
	//比较大小
	while (i != 15 && j != 11) {
		if (a1[i] < a2[j])
			a3[k++] = a1[i++];
		else
			a3[k++] = a2[j++];
	}
	//将剩下未比较的数据存入
	while (i != 15)
		a3[k++] = a1[i++];
	while (j != 11)
		a3[k++] = a2[j++];
	ofstream ofs3;
	ofs3.open("f3.txt", ios::out);
	for (int i = 0; i < 26; i++)
		ofs3 << a3[i] << " ";
	ofs3.close();
	//接下来打f3并输出到屏幕上
	double f3[26];
	ifstream ifs3;
	ifs3.open("f3.txt", ios::in);
	for (int i = 0; i < 26; i++) {
		ifs3 >> f3[i];
		cout << f3[i] << " ";
	}
	ifs3.close();
}