我正在嘗試使用unistd庫編寫/讀取文本文件。稍後我會將它部署到/ dev路徑中的文件。 我正在嘗試使用std::vector
而不是char buffer[]
。所以我寫了兩個實現,一個使用vector和另一個char緩衝區。在文件中都寫得很好,但都不能讀取文件。unistd read()不起作用
這裏是我的測試代碼:
使用緩衝焦炭
void tests_using_buffer_of_char(const std::string &path)
{
int file_descriptor_char;
char buffer[8] ={0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
std::cout << sizeof(buffer) << std::endl;
for(auto i = 0; i < sizeof(buffer); i++)
std::cout << buffer[i] << std::endl;
file_descriptor_char = open(path.c_str(), O_RDWR);
if(file_descriptor_char != -1)
std::cout << "open with success " << path << std::endl;
std::size_t size = strlen(buffer);
ssize_t write_bytes = write(file_descriptor_char, buffer, size);
std::cout << size << " <-- size of buffer " << write_bytes << " <-- size of writed bytes" << std::endl;
memset(&buffer[0], 0, sizeof(buffer));
ssize_t read_bytes = read(file_descriptor_char, &buffer, size);
std::cout << size << " <-- size of buffer " << read_bytes << " <-- size of readed bytes" << std::endl;
for(auto i = 0; i < sizeof(buffer); i++)
std::cout << buffer[i] << std::endl;
if(close(file_descriptor_char) != -1)
std::cout << "close with success "<< path << std::endl;
}
使用矢量
void tests_using_buffer_of_vector(const std::string &path)
{
int file_descriptor_vector;
std::vector<char> buffer = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
std::cout << buffer.size() << std::endl;
for(auto i : buffer)
std::cout << i << std::endl;
file_descriptor_vector = open(path.c_str(), O_RDWR);
if(file_descriptor_vector != -1)
std::cout << "open whit success " << path << std::endl;
ssize_t write_bytes = write(file_descriptor_vector, buffer.data(), buffer.size());
std::cout << buffer.size() << " <-- size of buffer " << write_bytes << " <-- size of writed bytes" << std::endl;
buffer.clear();
ssize_t read_bytes = read(file_descriptor_vector, buffer.data(), write_bytes);
std::cout << buffer.size() << " <-- size of buffer " << read_bytes << " <-- size of readed bytes" << std::endl;
for(auto i : buffer)
std::cout << i << std::endl;
if(close(file_descriptor_vector) != -1)
std::cout << "close with success " << path << std::endl;
}
的緩衝
謝謝大家!
'unistd'不是一個庫,它是POSIX系統上的一個C頭文件。當你知道* xy *是一個*標準函數時,你可能不應該寫「* xy *不起作用」,這對於數百萬程序員來說工作得很好,你可能只是錯誤地使用了它。 –
你是對的!謝謝你的建議。在接下來的問題中,我會更加精確和不那麼籠統地討論這個問題。 – gorn