auto
Use auto
STH in for (auto I: STH) can be something with an iterator, and I is each element in STH
Attribute of comparison
Less, less_equal, greater (from large to small), greater_equal are in the header file functional
Int bar [] = 15,10,20 {};
std::sort (bar, bar+3, std::less()); // from small to big
The string class
// constructor
String STRS // Generates an empty string
String s(STR) // Generates a copy of the string STR
@string s(STR, stridx) // Take the part of the string STR that begins with stridx as the initial value of the constructor
@string s(STR, strbegin, strlen) // Take the strlen part of the string beginning with strbegin as the initial value
String s(CSTR) // Use C_string CSTR as the initial value of string s
String s(CSTR,char_len) // Use the first char_len of C_string CSTR as the initial value of string s
Strings (num, c) // Generates a string containing num c characters
Strings (STRS, beg, end) // take characters from the interval [beg, end] (both iterators) as the initial value of strings
The above method of @ line can be applied to all functions
//c_str()
There is an implicit conversion from const char * to string, but there is no automatic conversion from string to C_string. String.c_str () returns C_string.
/ / the length
Length () or size() returns the length of the string
/ / to compare
S pare (pos,n, s2,pos2,n2)// use s-s2, return 1, -1,0
Lexicographical orders can be compared directly with the comparison operator
// Modify and replace
Str.assign (str1)// Assign str1 to STR
erase()
s.swap(s1)
insert()
append()
replace()
/ / input
The third argument to getline(cin,s) specifies the terminator
/ / to find
Find () before, rfind() after
Pair class (header Utility)
/ / structure
auto my_pair=make_pair(a,b)
Pair < type, type > my_pair(a,b)
/ / access
My_pair. First or second
/ / to compare
First before second, in lexicographical order
/ / exchange
Swap () function
Map class (default sort is less)
/ / structure
Each pair can be either {a,b} or make_pair(a,b)
/ / insert
Insert (pair object)
Count (STR)// Counts the number of occurrences of STR in each key
Emplace (a,b)// insert {a,b} as a pair
/ / to find
Find ()// Returns the iterator type
/ / the length
size()
/ / access
Value is accessed directly by key using subscripts
/ / delete
Erase (key)// Delete the pair corresponding to the key