Thanks to visit codestin.com
Credit goes to cplusplus.com

C++

Reference

<string>

string

public member function
<string>

std::string::operator+=

string (1)
string& operator+= (const string& str);
c-string (2)
string& operator+= (const char* s);
character (3)
string& operator+= (char c);
string (1)
string& operator+= (const string& str);
c-string (2)
string& operator+= (const char* s);
character (3)
string& operator+= (char c);
initializer list (4)
string& operator+= (initializer_list<char> il);
Append to string
Extends the string by appending additional characters at the end of its current value:

(See member function append for additional appending options).

Parameters

str
A string object, whose value is copied at the end.
s
Pointer to a null-terminated sequence of characters.
The sequence is copied at the end of the string.
c
A character, which is appended to the current value of the string.
il
An initializer_list object.
These objects are automatically constructed from initializer list declarators.
The characters are appended to the string, in the same order.

Return Value

*this

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
 
// string::operator+=
#include <iostream>
#include <string>

int main ()
{
  std::string name ("John");
  std::string family ("Smith");
  name += " K. ";         // c-string
  name += family;         // string
  name += '\n';           // character

  std::cout << name;
  return 0;
}

Output:
John K. Smith


Complexity

Unspecified, but generally up to linear in the new string length.

Iterator validity

Any iterators, pointers and references related to this object may be invalidated.

Data races

The object is modified.

Exception safety

Strong guarantee: if an exception is thrown, there are no changes in the string.

If the resulting string length would exceed the max_size, a length_error exception is thrown.
A bad_alloc exception is thrown if the function needs to allocate storage and fails.

See also

string::append
Append to string (public member function)
string::assign
Assign content to string (public member function)
string::operator=
String assignment (public member function)
string::insert
Insert into string (public member function)
string::replace
Replace portion of string (public member function)