IO库的举例

#include <iostream>#include <fstream>#include <string>#include <vector>using namespace std;int fileToVector(string fileName, vector<string>& svec){ifstream inFile(fileName.c_str());if (!inFile)return 1;string s;//while (getline(inFile, s)) // 一次输入一行，//svec.push_back(s); // 一次输入一行， while(inFile >> s)  // 一次输入一个单词，svec.push_back(s);   // 一次输入一个单词，inFile.close();if (inFile.eof())return 4;if (inFile.bad())return 2;if (inFile.fail())return 3;}int main(){cout << "ok? " << endl;vector<string> svec;string fileName, s;cout << "Enter fileName: ";cin >> fileName;switch (fileToVector(fileName, svec)){case 1:cout << "error: can not open file. " << fileName << endl;return -1;case 2:cout << "error: system failure. " << endl;return -1;case 3:cout << "error: read failure. " << endl;return -1;}cout << "向量里的内容：" << endl;for (vector<string>::iterator iter = svec.begin();iter != svec.end(); ++iter)cout << *iter << endl;cout << "文件有多少行：" << svec.size() << endl;return 0;}