C + + Self-study Note _ Standard library Type _ C + + Primer

1. Standard library String type

1.1 The definition and initialization of a string object

string s1;             // default constructor, S1 is empty string string s2 (S1);         // Initialize S2 to a copy of S1 string S3 ("value");    // initializes S3 to a copy of a string literal string S4 (n,'C');      // Initialize S4 to n copies of character ' C '

1.2 The read and write of a string object

int Main () {  string  s;  Cin>>s;  cout<<s<<Endl;   return 0 ;}

Reads a string from the standard input and stores the read-in string in S. Note that the following 2 points are:

　　　　·  Reads and ignores all whitespace characters (such as spaces, line breaks, tabs) at the beginning;

　　　　·  Reads the character until it encounters a whitespace character again, and the read terminates.

So if you enter " Hello World", the result is "Hello".

1.3 Reading entire lines of text with Getline

This function accepts 2 parameters: an input stream object and a string object.

int Main () {   string line ;     while (Getline (cin,line))      cout<<line<<Endl;    return 0 ;}

It is important to note that:

　　　　·  Getline does not ignore the beginning of the newline character, when I come up and enter a newline character, Getline will think I have lost a line, and then stop reading and return, so if the first character is a newline character, the string parameter will be set to an empty string.

　　　　·  The getline encounters a newline character return, but the newline character is removed from the buffer, so the next time you read it, there is no line break.

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C + + Self-study Note _ Standard library Type _ C + + Primer