std::ios_base::seekdir

 

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typedef /*implementation defined*/ seekdir;
static constexpr seekdir beg = /*implementation defined*/ static constexpr seekdir end = /*implementation defined*/ static constexpr seekdir cur = /*implementation defined*/

指定文件查找方向类型。定义了以下常量

常量	说明
beg	流的开头
end	流的结尾
cur	流位置指示器的当前位置

示例

运行此代码

#include <iostream>
#include <sstream>
#include <string>
 
int main()
{
    std::istringstream in("Hello, World!");
    std::string word1, word2, word3, word4, word5;
 
    in >> word1;
    in.seekg(0, std::ios_base::beg); // <- rewind
    in >> word2;
    in.seekg(1, std::ios_base::cur); // -> seek from cur pos toward the end
    in >> word3;
    in.seekg(-6, std::ios_base::cur); // <- seek from cur pos (end) toward begin
    in >> word4;
    in.seekg(-6, std::ios_base::end); // <- seek from end toward begin
    in >> word5;
 
    std::cout << "word1 = " << word1 << '\n'
              << "word2 = " << word2 << '\n'
              << "word3 = " << word3 << '\n'
              << "word4 = " << word4 << '\n'
              << "word5 = " << word5 << '\n';
}

输出

word1 = Hello,
word2 = Hello,
word3 = World!
word4 = World!
word5 = World!

另请参阅

seekg	设置输入位置指示器 (std::basic_istream<CharT,Traits> 的公共成员函数)
seekp	设置输出位置指示器 (std::basic_ostream<CharT,Traits> 的公共成员函数)
pubseekoff	调用 seekoff() (std::basic_streambuf<CharT,Traits> 的公共成员函数)