String

string的method

（generated by ChatGPT）

Method	Description	Example
length() or size()	Returns the number of characters in the string.	s.length(); or s.size();
empty()	Checks if the string is empty.	s.empty();
clear()	Clears the string, making it empty.	s.clear();
append(str)	Appends str to the end of the string.	s.append(" world");
operator+=	Concatenates another string or character.	s += " world";
insert(pos, str)	Inserts str at position pos.	s.insert(5, " hello");
erase(pos, len)	Erases len characters from position pos.	s.erase(5, 3);
replace(pos, len, str)	Replaces len characters starting at pos with str.	s.replace(5, 3, "world");
substr(pos, len)	Returns a substring starting at pos with len characters.	s.substr(0, 5);
find(str)	Finds the first occurrence of str and returns its position. Returns std::string::npos if not found.	s.find("hello");
rfind(str)	Finds the last occurrence of str.	s.rfind("hello");
find_first_of(str)	Finds the first occurrence of any character in str.	s.find_first_of("aeiou");
find_last_of(str)	Finds the last occurrence of any character in str.	s.find_last_of("aeiou");
find_first_not_of(str)	Finds the first character not in str.	s.find_first_not_of("abc");
find_last_not_of(str)	Finds the last character not in str.	s.find_last_not_of("abc");
compare(str)	Compares the string with str. Returns 0 if equal, <0 if less, >0 if greater.	s.compare("hello");
c_str()	Returns a C-style null-terminated character array.	const char* c = s.c_str();
data()	Returns a pointer to the underlying character array (similar to c_str() but not null-terminated).	const char* d = s.data();
at(pos)	Returns the character at position pos (with bounds checking).	char c = s.at(5);
operator[]	Returns the character at position pos (no bounds checking).	char c = s[5];
push_back(ch)	Appends a character ch to the end of the string.	s.push_back('!');
pop_back()	Removes the last character from the string.	s.pop_back();
resize(n)	Resizes the string to contain n characters.	s.resize(10);
swap(str)	Swaps the contents of the string with str.	s.swap(otherString);
begin()	Returns an iterator to the beginning of the string.	auto it = s.begin();
end()	Returns an iterator to the end of the string.	auto it = s.end();
rbegin()	Returns a reverse iterator to the beginning of the reversed string.	auto it = s.rbegin();
rend()	Returns a reverse iterator to the end of the reversed string.	auto it = s.rend();
to_string(val)	Converts a number (int, float, etc.) to a string.	std::to_string(123);
stoi(str)	Converts a string to an integer.	int num = std::stoi("123");
stof(str)	Converts a string to a floating-point number.	float num = std::stof("123.45");
getline(cin, str)	Reads an entire line of input into the string.	std::getline(std::cin, s);

注意rbegin的含义是reversed的string起始字符串的迭代器

Note:

string 风格的字符串用printf("%s")打印会出现乱码，因为这个不适合string风格。想要用printf的话，需要这么写：printf("%d",str.c_str());即调用成员函数c_str();