1, common string class object constructor
| Function name | Function Description |
|---|---|
| string() | Empty string class object configuration |
| string(const char * s) | Construct with C-string string class object |
| string(size_t n, char c) | string class object containing n characters c |
| string(const string&s) | Copy constructor |
| string(const string&s, size_t n) | The new class object with the string configuration the first n characters of s |
2, string class object operation capacity
| Function name | Function Description |
|---|---|
| size_t size() const | Returns a string length of valid characters |
| size_t length() const | Returns a string length of valid characters |
| size_t capacity( ) const | Returns the total size of space |
| bool empty() const | Detecting the release of the string is empty string is true, false otherwise |
| void clear() | Empty effective character |
| void resize(size_t n, char c) | The effective number of characters into a number n, the extra space is filled with character c |
| void resize(size_t n) | The number of valid characters into the n, the extra space is filled with a 0 |
| void reserve(size_t res_arg=0) | Reserve space for the string |
Note:
1. There is no difference in the size and length size of the length of the string
2. String default capacity capacity VS environment 15, each expansion 16, the total capacity of the multiple -116, the final position is' \ 0 '. (Sequence table corresponding to the character string)
3.empty (); // empty sentence, a return is empty, non-empty return 0
4.clear (); // empty, without changing the size of the capacity of
5.reserve // expansion reserve space
string s1;
s1.reserve(500);
cout << s1.capacity() << endl;//输出为511，500之后第一个16的倍数-1
6.resize: directly change the value of size, space reset. If the value exceeds the value resize capacity, it will first call the reserve allocated space
7.reserve, resize, clear, does not result in narrow space
