In practice, the string series in c ++ -- string connection (+ = or append or push_back)

In practice, the string series in c ++ -- string connection (+ = or append or push_back)

String connections are also frequently used. string reloads some operators:
First, let's take a look at the overload + operator, which is used to concatenate two string objects:
Source code:

template
  
      basic_string
   
     operator+(      const basic_string
    
     & _Left,      const basic_string
     
      & _Right   );template
      
        basic_string
       
         operator+( const basic_string
        
         & _Left, const CharType* _Right );template
         
           basic_string
          
            operator+( const basic_string
           
            & _Left, const CharType _Right );template
            
              basic_string
             
               operator+( const CharType* _Left, const basic_string
              
               & _Right );template
               
                 basic_string
                
                  operator+( const CharType _Left, const basic_string
                 
                  & _Right );template
                  
                    basic_string
                   
                    && operator+( const basic_string
                    
                     & _Left, const basic_string
                     
                      && _Right);template
                      
                        basic_string
                       
                        && operator+( const basic_string
                        
                         && _Left, const basic_string
                         
                          & _Right);template
                          
                            basic_string
                           
                            && operator+( const basic_string
                            
                             && _Left, const basic_string
                             
                              && _Right);template
                              
                                basic_string
                               
                                && operator+( const basic_string
                                
                                 && _Left, const CharType *_Right);template
                                 
                                   basic_string
                                  
                                   && operator+( const basic_string
                                   
                                    && _Left, CharType _Right);template
                                    
                                      basic_string
                                     
                                      && operator+( const CharType *_Left, const basic_string
                                      
                                       && _Right);template
                                       
                                         basic_string
                                        
                                         && operator+( CharType _Left, const basic_string
                                         
                                          && _Rig
                                         
                                        
                                       
                                      
                                     
                                    
                                   
                                  
                                 
                                
                               
                              
                             
                            
                           
                          
                         
                        
                       
                      
                     
                    
                   
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     
    
   
  

Note:

# Include
  
   
# Include
   
    
Int main () {std: string my_str = "holiday"; std: string my_str_add = "error" + "error"; // error std :: string my_str_add2 = my_str + "right"; std: string my_str_add3 = my_str + "right" + "right"; std: string my_str_add4 = "right" + my_str; std :: string my_str_add5 = "error" + "error" + my_str; // return 0 ;}
   
  

Start with the question below!
+ =
* Append a character to a string *

basic_string
  
   & operator+=(   value_type _Ch);basic_string
   
    & operator+=(   const value_type* _Ptr);basic_string
    
     & operator+=(   const basic_string
     
      & _Right);
     
    
   
  

Append
* Add the character to the end of the string *

basic_string
  
   & append(    const value_type* _Ptr);basic_string
   
    & append(    const value_type* _Ptr,    size_type _Count);basic_string
    
     & append(    const basic_string
     
      & _Str,    size_type _Off,    size_type _Count);basic_string
      
       & append( const basic_string
       
        & _Str);basic_string
        
         & append( size_type _Count, value_type _Ch);template
         
           basic_string
          
           & append( InputIterator _First, InputIterator _Last );basic_string
           
            & append( const_pointer _First, const_pointer _Last);basic_string
            
             & append( const_iterator _First, const_iterator _Last);
            
           
          
         
        
       
      
     
    
   
  

There are multiple overload functions, so there are multiple usage methods:

   string str1a ( "Hello " );   const char *cstr1a = "Out There ";   str1a.append ( cstr1a );   string str1b ( "Hello " );   const char *cstr1b = "Out There ";   str1b.append ( cstr1b , 3 );   string str1c ( "Hello " ), str2c ( "Wide World " );      str1c.append ( str2c , 5 , 5 );   string str1d ( "Hello " ), str2d ( "Wide " ), str3d ( "World " );   str1d.append ( str2d );   str1d += str3d;   string str1e ( "Hello " );   str1e.append ( 4 , '!' );   string str1f ( "Hello " ), str2f ( "Wide World " );   str1f.append ( str2f.begin ( ) + 5 , str2f.end ( ) - 1 );

Push_back
* Add the element to the end of the string *

void push_back(    value_type _Ch);

Note that the following code is incorrect:

My_str.push_back ("123"); // error my_str.push_back ('1'); // OK