C++流istream,ifstream,istringstream的使用

文件头

#include <iostream>#include <fstream>#include <string>#include <vector>#include <sstream>

using namespace std;

从文件中逐词读取

void getFromFile() {

	ifstream fin("C:\\data.txt");

	string s;

	while (fin >> s)
	{
		cout << "Read from file:" <<  s << endl;
	}

	
}

从文件中逐行读取

void getFromFileByLine() {

	ifstream fin("C:\\data.txt");

	string s;

	while (getline(fin, s))
	{
		cout << "Read from file:" << s << endl;
	}


}

从文件中逐词读取并写入vector容器中

void fileToVectorByWord() {

	ifstream infile;
	infile.open("C:\\data.txt");
	if (!infile) {    //加入异常判断

		cout << "error : cannot open the file" << endl;
	}

	vector<string> v;
	string s;
	while (!infile.eof()) {
		infile >> s;
		v.push_back(s);

	}

	vector<string>::const_iterator it = v.begin();  //开始验证
	while (it != v.end()) {
		cout << *it << endl;
		++it;
	}

}

从文件中逐行读取并写入vector容器中

void fileToVectorByLine() {

	ifstream infile;
	infile.open("C:\\data.txt");
	if (!infile) {

		cout << "error : cannot open the file" << endl;
	}

	vector<string> v;
	string s;
	while (! infile.eof()) {
		getline(infile, s);
		v.push_back(s);

	}

	vector<string>::const_iterator it = v.begin();
	while (it != v.end()) {
		cout << *it << endl;
		++it;
	}

}

istringstream的使用

void testStringstream()
{
	string line;
	string word;
	while (getline(cin, line)) {   //从控制台获取一行字符
		
		istringstream stream(line);  //将line绑定成istringstream

		while (stream >> word) {  //逐词输出
			cout << word << endl;  
		}
	
	}

}