c++文件打开和关闭

news/2024/7/20 22:17:11 标签: c++, ios, buffer, file, mfc, c

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content_views" class="htmledit_views"> cii-font-family: 宋体">一般使用fstream 类中所定义的成员函数 open( )和 close( )。

class="O" style="mso-margin-left-alt: 216"> cii-font-family: 宋体"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">fstream outclass="tags" href="/tags/FILE.html" title=file>file; 定义一个fstream类的对象

class="O" style="mso-margin-left-alt: 216"> cii-font-family: 宋体">cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">cerun: yes"> outclass="tags" href="/tags/FILE.html" title=file>file.open("f1.txt", class="tags" href="/tags/IOS.html" title=ios>ios::out);cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">

class="O" style="mso-margin-left-alt: 216"> cii-font-family: 宋体">cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">或者 cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">fstream outclass="tags" href="/tags/FILE.html" title=file>file("f1.txt", class="tags" href="/tags/IOS.html" title=ios>ios::out);cerun: yes">

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">cerun: yes"> cii-font-family: 'Times New Roman'">内容；如果文件不存在࿰c;则创建新文件

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">noreplacecerun: yes"> cii-font-family: 'Times New Roman'">如果文件存在࿰c;除非设置 cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">class="tags" href="/tags/IOS.html" title=ios>ios::ate cii-font-family: 'Times New Roman'">或 cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">class="tags" href="/tags/IOS.html" title=ios>ios::app, cii-font-family: 'Times New Roman'">否则打

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">class="tags" href="/tags/IOS.html" title=ios>ios::in|class="tags" href="/tags/IOS.html" title=ios>ios::outcerun: yes"> cii-font-family: 'Times New Roman'">以读和写的方式打开文件

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">class="tags" href="/tags/IOS.html" title=ios>ios::out|class="tags" href="/tags/IOS.html" title=ios>ios::binarycerun: yes"> cii-font-family: 'Times New Roman'">以二进制写方式打开文件

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">class="tags" href="/tags/IOS.html" title=ios>ios::in|class="tags" href="/tags/IOS.html" title=ios>ios::binarycerun: yes"> cii-font-family: 'Times New Roman'">以二进制读方式打开文件

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">

class="O" style="mso-margin-left-alt: 336"> cii-font-family: 'Times New Roman'">未指定 cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">binary cii-font-family: 'Times New Roman'">方式时࿰c;文件都以文本方式打开,若指定了 cii-font-family: 'Times New Roman'">cerun: yes"> binary cii-font-family: 'Times New Roman'">方式࿰c;则文件以二进制方式打开.

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">

class="O" style="mso-margin-left-alt: 216; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1">

class="O" style="mso-margin-left-alt: 336; mso-line-spacing: '90 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">cerun: yes"> ofstream outclass="tags" href="/tags/FILE.html" title=file>file("f1.txt", class="tags" href="/tags/IOS.html" title=ios>ios::out);cerun: yes"> cii-font-family: 'Times New Roman'">写

class="O" style="mso-margin-left-alt: 336; mso-line-spacing: '90 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">cerun: yes"> ifstream istrm("f2.txt");cerun: yes"> cii-font-family: 'Times New Roman'">读

class="O" style="mso-margin-left-alt: 336; mso-line-spacing: '90 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">

class="O" style="mso-margin-left-alt: 384; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'">读写完不要忘了关闭文件

cii-font-family: 'Times New Roman'">

class="O" style="mso-margin-left-alt: 216; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">//

class="O" style="mso-margin-left-alt: 216; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">例如：

class="O" style="mso-margin-left-alt: 216; mso-line-spacing: '80 20 0'; mso-char-wrap: 1; mso-kinsoku-overflow: 1"> cii-font-family: 'Times New Roman'; mso-fareast-language: ZH-CN">MFC主要读写文件的类是CFile,而CStdioFile类是派生自CFile类的࿰c;主要增加了一个按行的方式读取/写入文件每行字符串的功能!别的地方没咋研究!

//CFile读取所有文件到缓冲区：
CFile class="tags" href="/tags/FILE.html" title=file>file;
char class="tags" href="/tags/BUFFER.html" title=buffer>buffer[1024];
if(!class="tags" href="/tags/FILE.html" title=file>file.Open("c://aaa.txt",CFile::modeRead))return; //打开aaa这个文件࿰c;打开形式为读取
class="tags" href="/tags/FILE.html" title=file>file.Read(class="tags" href="/tags/BUFFER.html" title=buffer>buffer,1024); //将文件的内容从开始࿰c;读1024到缓冲区(如果想读取不同地方的数据则需要设置游标函数Seek,SeekToBegin,SeekToEnd..)
class="tags" href="/tags/FILE.html" title=file>file.Close();

//CFile写内容到文件
CFile class="tags" href="/tags/FILE.html" title=file>file;
char class="tags" href="/tags/BUFFER.html" title=buffer>buffer[1024] = "在此添加要写入文件的字符串!";
if(!class="tags" href="/tags/FILE.html" title=file>file.Open("c://aaa.txt",CFile::Create | CFile::Write))return; //打开aaa这个文件࿰c;打开形式为(无此文件则新建)写入
class="tags" href="/tags/FILE.html" title=file>file.Write(class="tags" href="/tags/BUFFER.html" title=buffer>buffer,strlen(class="tags" href="/tags/BUFFER.html" title=buffer>buffer));
class="tags" href="/tags/FILE.html" title=file>file.Close();

//CStdioFile类的例子：
CStdioFile class="tags" href="/tags/FILE.html" title=file>file;
CString str; //StdioFile可以直接使用字符串类CString的类型
if(!class="tags" href="/tags/FILE.html" title=file>file.Open("c://aaa.txt",CFile::modeRead))return; //打开aaa这个文件࿰c;打开形式为读取
class="tags" href="/tags/FILE.html" title=file>file.ReadString(str); //读一行内容到str字符串࿰c;注意此时文件的游标将自动设置到下一行的开头位置࿰c;所以如果想读下一行还是用class="tags" href="/tags/FILE.html" title=file>file.ReadString(str);
class="tags" href="/tags/FILE.html" title=file>file.Close();

class="O" style="mso-margin-left-alt: 336; mso-line-spacing: '100 50 0'">

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