C++ cin 物件

❮ iostream 物件

int x; 
cout << "Type a number: "; // Type a number and press enter
cin >> x; // Get user input from the keyboard
cout << "Your number is: " << x; // Display the input value 

定義和用法

The cin object is used to read keyboard input or data from a file. (cin 物件用於讀取鍵盤輸入或檔案資料。)

The most common way to use cin is with the >> extraction operator. The extraction operator converts input data to the appropriate type for the variable (最常用的使用 cin 的方法是使用 >> 提取運算子。提取運算子將輸入資料轉換為變數的適當型別)

int x;
cin >> x;

The extraction operator can be used more than once on the same line to put data into multiple variables (提取運算子可以在同一行上多次使用，將資料放入多個變數中)

int x, y;
cin >> x >> y;

Note: The cin object is defined in the <iostream> header file. (注意： cin 物件定義在 <iostream> 標頭檔案中。)

方法

In addition to the >> extraction operator, the cin object also has methods to read input. (除了 >> 提取運算子外，cin 物件還有用於讀取輸入的方法。)

get()

The cin.get() method reads one character from the input source and returns it. ( cin.get() 方法從輸入源讀取一個字元並返回它。)

char c = cin.get();
cout << c;

The cin.get(str, n) method writes up to n characters into the char array str which are copied from the input source. If a new line character \n is found it stops at the new line without including it. The last written character is always a null terminating character \0. ( cin.get(str, n) 方法將從輸入源複製的最多 n 個字元寫入 char 陣列 str 中。如果找到換行符 \n，它會在不包含換行符的情況下停止。最後一個寫入的字元始終是一個空終止字元 \0。)

An extra parameter can be used to specify a different character than \n as a delimiter. (可以使用額外引數指定一個不同於 \n 的字元作為分隔符。)

char str[20];
cin.get(str, 5);
cout << c;

// Stop reading when a "." is found
cin.get(str, 5, '.');
cout << c;

getline()

The cin.getline(str, n) method is the same as get(str, n) except that when the new line character \n or specified delimiter is found, it is discarded from the input source so that the next cin operation won't use it. ( cin.getline(str, n) 方法與 get(str, n) 相同，不同之處在於，當找到換行符 \n 或指定的分隔符時，它會被從輸入源中丟棄，以便下一次 cin 操作不會使用它。)

char str[20];
cin.getline(str, 5);
cout << c;

// Stop reading when a "." is found
cin.getline(str, 5, '.');
cout << c;

read()

The cin.read(str, n) method reads up to n characters from the input source and writes them into the char array str without checking for delimiters and without adding a null terminating character \0. ( cin.read(str, n) 方法從輸入源讀取最多 n 個字元，並將它們寫入 char 陣列 str 中，而不檢查分隔符，也不新增空終止字元 \0。)

char str[] = "Hello World";
cin.read(str, 5);
cout << str;

gcount()

The cin.gcount() method returns the number of characters that were used from the input souce by one of the above methods. ( cin.gcount() 方法返回上述方法中使用的來自輸入源的字元數。)

char str[20];
cin.get(str, 5);
int num = cin.gcount();
cout << "Read " << num << " characters and got " << str << "\n";

❮ iostream 物件