std::ofstream 是否保证在打开新文件时关闭旧文件？
Does std::ofstream guarantee the old open file will be closed if opening new one?
#include <fstream>
int main()
{
auto fout = std::ofstream("/tmp/a.txt");
fout.open("/tmp/b.txt"); // Will "/tmp/a.txt" be closed?
fout.open("/tmp/c.txt"); // Will "/tmp/b.txt" be closed?
}
std::ofstream 是否保证打开新文件时关闭旧文件？
第二次及后续调用将失败。
[filebuf.members]
basic_filebuf* open(const char* s, ios_base::openmode mode);
2 Effects: If is_open() != false, returns a null pointer. Otherwise...
[ofstream.members]
void open(const char* s, ios_base::openmode mode = ios_base::out);
3 Effects: Calls rdbuf()->open(s, mode | ios_base::out). If that function does not return a null pointer calls clear(), otherwise calls setstate(failbit)
#include <fstream>
int main()
{
auto fout = std::ofstream("/tmp/a.txt");
fout.open("/tmp/b.txt"); // Will "/tmp/a.txt" be closed?
fout.open("/tmp/c.txt"); // Will "/tmp/b.txt" be closed?
}
std::ofstream 是否保证打开新文件时关闭旧文件？
第二次及后续调用将失败。
[filebuf.members]
basic_filebuf* open(const char* s, ios_base::openmode mode);
2 Effects: Ifis_open() != false, returns a null pointer. Otherwise...
[ofstream.members]
void open(const char* s, ios_base::openmode mode = ios_base::out);
3 Effects: Callsrdbuf()->open(s, mode | ios_base::out). If that function does not return a null pointer callsclear(), otherwise callssetstate(failbit)