public member function
<streambuf> <iostream>
Advance to next position and get character
Advances the current position of the controlled input sequence to the next character, and returns that next character.
請注意，雖然相似，但以下成員函式的行為有所不同
| 成員函式，逐個字元列印字串的內容 | 描述 |
|---|
sgetc() | 返回當前位置的字元。 |
sbumpc() | 返回當前位置的字元，並將當前位置推進到下一個字元。 |
snextc() | 將當前位置推進到下一個字元，並返回該下一個字元。 |
Internally, the function first calls sbumpc, and if that function returns a valid character, the function then calls sgetc. This only calls virtual members if, at some point, there are no read positions available at the get pointer (gptr).
其行為等同於如下實現：
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int snextc() {
if ( sbumpc() == EOF ) return EOF;
else return sgetc();
}
|
返回值
The character at the next position of the controlled input sequence, as a value of type int.
If there are no more characters to read from the controlled input sequence, the function returns the end-of-file value (EOF).
示例
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// show file content - snextc() example
#include <iostream> // std::cout, std::streambuf
#include <fstream> // std::ifstream
#include <cstdio> // EOF
int main () {
std::ifstream istr ("test.txt");
if (istr) {
std::streambuf * pbuf = istr.rdbuf();
do {
char ch = pbuf->sgetc();
std::cout << ch;
} while ( pbuf->snextc() != EOF );
istr.close();
}
return 0;
}
|
This example shows the content of a file on screen, using the combination of sgetc and snextc to read the input file.
資料競爭
修改*流緩衝區*物件。
同時訪問同一*流緩衝區*物件可能會導致資料競爭。
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。