public member function
<streambuf> <iostream>
streamsize sputn (const char_type* s, streamsize n);
Put sequence of characters
Calls the protected virtual member xsputn with the same arguments s and n.
The default definition of xsputn in basic_streambuf writes characters from the array pointed to by s into the controlled output sequence, until either n characters have been written or the end of the output sequence is reached.
引數
- s
- 指向要寫入的字元序列的指標。
成員型別 char_type 是流緩衝區（第一個類模板引數）中字元的型別。
- n
- 要寫入的字元數。
這應該是一個非負值。
streamsize 是一個帶符號整型。
示例
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// sputn() example
#include <iostream> // std::streambuf
#include <fstream> // std::ofstream
int main () {
const char sentence[]= "Sample sentence";
std::ofstream ostr ("test.txt");
if (ostr) {
std::streambuf * pbuf = ostr.rdbuf();
pbuf->sputn (sentence,sizeof(sentence)-1);
ostr.close();
}
return 0;
}
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This example writes a sentence to a file using streambuf's member sputn.
資料競爭
訪問 s 指向的陣列中最多前 n 個字元。
修改*流緩衝區*物件。
對同一陣列或同一流緩衝區物件的併發訪問可能會引入資料爭用。
異常安全
基本保證：如果丟擲異常，則流緩衝區處於有效狀態（這也適用於標準派生類）。
無效引數會導致未定義行為。