因为文件一事差点怀疑编译器，三份代码对比

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//因为这里不小心把文件关了？！！！ifs.close();#include<cstdio>#include<fstream>#include<iostream>using namespace std;//之所以gcount输出10其实不是10，其实是16.因为当用这个len作for循环的时候其实是16 int main(){ifstream ifs("L8_F3_Z1.dat",ios::binary);if(!ifs){cout<<"Error opening file\n";return 1; } int len;unsigned char txt[100][4];int number[1000];int count=0;cout<<sizeof(int)<<endl;ifs.seekg(0,ios::end);cout<<"The whole chars of this file is "<<ifs.tellg()<<endl;//因为这里不小心把文件关了？！！！ifs.close();len=ifs.tellg()/4;//find len firstly dont use !ifs ,because it may cause more EOF ifs.seekg(0,ios::beg);while(count<len){//!ifs means what ifs.read(reinterpret_cast<char*>(&txt[count]),sizeof(int));//将读取到的数强制转换成char型，因为这个txt是char型指针 count++;}cout<<count<<endl;ifs.close();ofstream ofs("L8_F3_Z1.dat",ios::binary|ios::out|ios::trunc);if(!ofs){cout<<"Error opening file\n";return 1; } ofs.seekp(0,ios::end);int nowPosition=ofs.tellp();cout<<"The position now is "<<nowPosition<<endl;ofs.seekp(0,ios::beg);for(int i=0;i<count;i++){ofs.seekp(i*4,ios::beg);ofs.write(reinterpret_cast<char*>(&txt[count-i-1]), sizeof(int));}ofs.close();return 0;}

DeadL7.cpp

#include<cstdio>  #include<fstream>  #include<iostream>  using namespace std;  //之所以gcount输出10其实不是10，其实是16.因为当用这个len作for循环的时候其实是16   int main(){      ifstream ifs("L8_F3_Z1.dat",ios::binary);      if(!ifs){          cout<<"Error opening file\n";          return 1;       }       int len;      unsigned char txt[100][4];      int number[1000];      int count=0;      cout<<sizeof(int)<<endl;      string sentence;         ifs.seekg(0,ios::end);      cout<<"The whole chars of this file is "<<ifs.tellg()<<endl;      //最后完成只是改了这里而已，其实也没有做什么，可能就是语法的设置问题吧       len=ifs.tellg()/4;      ifs.seekg(0,ios::beg);      while(count<len){//!ifs means what           ifs.read(reinterpret_cast<char*>(&txt[count]),sizeof(int));//将读取到的数强制转换成char型，因为这个txt是char型指针                     cout<<"txt:"<<txt[count]<<endl;          cout<<"txt1:"<<setfill('0')<<setw(2)<<hex<<static_cast<int>(txt[count][1]-'0')<<":";          cout<<"txt2:"<<setfill('0')<<setw(2)<<hex<<static_cast<int>(txt[count][2]-'0')<<":";          cout<<"txt3:"<<setfill('0')<<setw(2)<<hex<<static_cast<int>(txt[count][3]-'0')<<":";          cout<<"txt4:"<<setfill('0')<<setw(2)<<hex<<static_cast<int>(txt[count][4]-'0')<<endl;            //      int txt1=(txt[1]-'0')<<12;  //      int txt2=(txt[2]-'0')<<8;  //      int txt3=(txt[3]-'0')<<4;  //      int txt4=txt[4]-'0';  //      number[count]=txt1+txt2+txt3+txt4;  //      cout<<number[count]<<endl;          count++;      }      cout<<count<<endl;      ifs.close();            //before open it, clear all       ofstream ofs("L8_F3_Z1.dat",ios::binary|ios::out|ios::trunc);            if(!ofs){          cout<<"Error opening file\n";          return 1;       }       ofs.seekp(0,ios::end);      int nowPosition=ofs.tellp();      cout<<"The position now is "<<nowPosition<<endl;            ofs.seekp(0,ios::beg);      for(int i=0;i<count;i++){          ofs.seekp(i*4,ios::beg);          ofs.write(reinterpret_cast<char*>(&txt[count-i-1]), sizeof(int));      }      ofs.close();      return 0;  }

DeadAgainL7.cpp

#include<cstdio>  #include<fstream>  #include<iostream>  using namespace std;  //之所以gcount输出10其实不是10，其实是16.因为当用这个len作for循环的时候其实是16   int main(){      ifstream ifs("L8_F3_Z1.dat",ios::binary);      if(!ifs){          cout<<"Error opening file\n";          return 1;       }       int len;      unsigned char txt[100][4];      int number[1000];      int count=0;      cout<<sizeof(int)<<endl;      string sentence;         ifs.seekg(0,ios::end);      cout<<"The whole chars of this file is "<<ifs.tellg()<<endl;      //最后完成只是改了这里而已，其实也没有做什么，可能就是语法的设置问题吧       len=ifs.tellg()/4;      ifs.seekg(0,ios::beg);      while(count<len){//!ifs means what           ifs.read(reinterpret_cast<char*>(&txt[count]),sizeof(int));//将读取到的数强制转换成char型，因为这个txt是char型指针                     count++;      }      cout<<count<<endl;      ifs.close();                 ofstream ofs("L8_F3_Z1.dat",ios::binary|ios::out|ios::trunc);            if(!ofs){          cout<<"Error opening file\n";          return 1;       }       ofs.seekp(0,ios::end);      int nowPosition=ofs.tellp();      cout<<"The position now is "<<nowPosition<<endl;            ofs.seekp(0,ios::beg);      for(int i=0;i<count;i++){          ofs.seekp(i*4,ios::beg);          ofs.write(reinterpret_cast<char*>(&txt[count-i-1]), sizeof(int));      }      ofs.close();      return 0;  }

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