std::basic_ostream::seekp
basic_ostream& seekp( pos_type pos ); | (1) | ? |
|---|---|---|
basic_ostream& seekp( off_type off, std::ios_base::seekdir dir); | (2) | ? |
设置当前关联的输出位置指示符。streambuf对象。
Behaves as UnformattedOutputFunction (except without actually performing output). After constructing and checking the sentry object, | (since C++11) |
|---|
1%29将输出位置指示符设置为相对于文件%29值开头的绝对%28。pos打电话rdbuf()->pubseekpos(pos,std::ios_base::out).如果呼叫返回(pos_type)-1，执行setstate(failbit)...
2%29将输出位置指示器设置为偏移。off相对于dir打电话rdbuf()->pubseekoff(off, dir,std::ios_base::out)...
Does not report errors. | (until C++14) |
|---|---|
If the call returns (pos_type)-1, executes setstate(failbit). | (since C++14) |
参数
pos | - | absolute position to set the output position indicator to. | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
off | - | relative position to set the output position indicator to. | ||||||||
dir | - | defines base position to apply the relative offset to. It can be one of the following constants: Constant Explanation beg the beginning of a stream end the ending of a stream cur the current position of stream position indicator | Constant | Explanation | beg | the beginning of a stream | end | the ending of a stream | cur | the current position of stream position indicator |
Constant | Explanation | |||||||||
beg | the beginning of a stream | |||||||||
end | the ending of a stream | |||||||||
cur | the current position of stream position indicator |
返回值
*this...
例外
1%5月29日投掷std::ios_base::failure如果失败，如果exceptions() & failbit != 0...
2%29
Does not throw unless rdbuf()->pubseekoff() throws | (until C++14) |
|---|---|
May throw std::ios_base::failure in case of failure, if exceptions() & failbit != 0. | (since C++14) |
例
二次
#include <sstream>
#include <iostream>
int main()
{
std::ostringstream os("hello, world");
os.seekp(7);
os << 'W';
os.seekp(0, std::ios_base::end);
os << '!';
os.seekp(0);
os << 'H';
std::cout << os.str() << '\n';
}二次
产出：
二次
Hello, World!二次
另见
tellp | returns the output position indicator (public member function) |
|---|---|
tellg | returns the input position indicator (public member function of std::basic_istream) |
seekg | sets the input position indicator (public member function of std::basic_istream) |
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