First acquaintance with string+ simple usage (II)

Let's take a look at this article string What other common ways ：

Catalog

insert-- Insert... At specified location

Insert characters （1）

Insert characters （2）

Insert string

erase-- Delete... In the specified location

Delete character

Delete the specified string  

swap--string Type exchange

string Class swap

Global function swap

c_str-- Return array pointer

 find-- Specify location lookup

To find the character

Find string

rfind-- Search back and forth

substr-- Take the string

getline-- Get a row

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insert-- Insert... At specified location

Insert characters （1）

string& insert (size_t pos, size_t n, char c);

pos Specify the location for ,n Is the number of characters ,c Represents the character to be inserted  

Just to show you ：

Insert characters （2）

iterator insert (iterator p, char c);

Point to insert a character , Regardless of the number of characters , Then you can use the parameter （ iterator , character ） Function of ：

A simple example ：

Insert string

string& insert (size_t pos, const char* s);

Simple demonstration ：

erase-- Delete... In the specified location

Delete character

iterator erase (iterator p);

Simple demonstration ：

Delete the specified string  

string& erase (size_t pos = 0, size_t len = npos);

Simple demonstration ：

Among them len Default equal to npos,npos Is a static member variable ：

When the second parameter is not given len When explicit value , It will be deleted from the beginning to the end of the string .

When given len When the value is greater than the length of the original string , and len Without assignment, the effect is the same , Delete until the end of the string .

swap--string Type exchange

string Class swap

void swap (string& str);

What is exchanged is the pointer of two objects , The content pointed to by the pointer changes , High exchange efficiency ：

Global function swap

Is the exchange of content , But because it is a custom type , It will involve deep copy , Low efficiency , Spending big ：

c_str-- Return array pointer

Is equivalent to string Types become more familiar to us char* type ：

Simple demonstration ：

int main()
{
	string s1("hello");
	cout << typeid(s1).name() << endl;
	cout << typeid(s1.c_str()).name() << endl;
	return 0;
}

 find-- Specify location lookup

To find the character

size_t find (char c, size_t pos = 0) const;

  Find the character at the specified position , Returns the subscript position of the matched character , Otherwise return to npos-- Shaping max

Find string

size_t find (const char* s, size_t pos = 0) const;

Specify the starting position to find the matching substring , Return the subscript position at the beginning of the substring, otherwise return npos

From the subscript for 6 Start looking for , Match to string , Returns the subscript position of a string  

rfind-- Search back and forth

and find Function the same , It's just that the starting direction is different , One before, one after , It's easy to understand

substr-- Take the string

string substr (size_t pos = 0, size_t len = npos) const;

 pos Is the starting position ,len Is the length of the substring , Return this substring

For example ：

 

If not found, it will return npos, It can be used as a judgment condition  

int main()
{
	string s1("xxxxxxxxhelloaaaaa");
	size_t end = s1.rfind('o');
	size_t pos = s1.find("hello");
	if(s1.find("hello")!=string::npos)
	{
		cout << s1.substr(pos, end - pos+1) << endl;
	}
	return 0;
}

getline-- Get a row

Will not be affected by spaces ：

When we use cin When entering a line of string , If there is a space in the middle , Will stop getting the string after the space ：

You can use getline, usage ：

istream& getline (istream& is, string& str);

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string That's the end of the common usage of , Partners interested in other usages can consult documents and learn independently , Recommended sites ：

cplusplus.com - C++ Resource networks

I hope to make progress with you ！！！