1、文件操作

一、从文件中读取数据ifstream>>

//功能：把文件中的数据读到变量的值中#include<fstream> #include <string>#include <iostream>using namespace std;int main(){    int i=0;    int count = 0; //文件中    string m_name , m_passwd;    ifstream file_read;  //定义读取文件的对象    file_read.open("name.txt");  //打开存放用户名和密码的文件    if(!file_read)    {        cout<<"打开文件失败"<<endl;    }    else    {        while(!file_read.eof()) //用此方法会多循环一次        {            file_read>>m_name>>m_passwd;  //一行一行            cout<<m_name<<"  "<<m_passwd<<endl;            i++;        }        count = i;  //因为多循环一次，所以i的初始值是0        file_read.close();    }}

二、往文件中写入数据ofstream<<

//功能：把变量的值写入到文件中//将数组m_name、m_passwd、sex中的数据写入文件中#include<fstream> #include <string>#include <iostream>using namespace std;int main(){    int i=0;    int count = 5; //文件中    string m_name[5] = {"AA","BB","CC","DD","EE"};    string m_passwd[5] = {"1","2","3","4","5"};    string sex[5] = {"M","M","W","W","M"};    ofstream file_write;    file_write.open("name.txt");    if(!file_write)    {        cout<<"打开文件失败"<<endl;    }    for(i=0;i<count;i++) //注意：空格、endl都可以写入文件中去        file_write<<m_name[i]<<"  "<<m_passwd[i]<<"  "<<sex[i]<<endl;}