C ++ basic syntax Learning (1)

(1) using:

The most common is:

 
# Include<Iostream>
Using NamespaceSTD;
 

More common:

 # Include  <  String  >  
# Include  <  Iostream >  
  Using  STD ::  String  ;
  Using  STD: CIN; // these three are in iostream
  Using  STD: Endl;
  Using  STD: cout;
  Using  STD: boolalpha; // explain this: the name of the string type of the output bool type is true or false.
  Using STD: Getline ;//GetlineRead the entire line of text  
  // Getline: as longGetlineIn case of a line break, even if it is the first character of the input,GetlineWill also stop reading and return.  // If the first character is a line breakStringThe parameter will be set to nullString. 

(2)StringObject operations:

S. Empty ()IfSIf it is an empty string, returnTrueOtherwise, returnFalse.

S. Size ()ReturnSNumber of characters in

S [N]ReturnSCenter:NStarts from 0.

S1 + S2SetS1AndS2Concatenates a new string and returns the new string.

S1 = S2SetS1Replace contentS2Copy

V1 = v2ComparisonV1AndV2, ReturnsTrueOtherwise, returnFalse

The following is an example of using the above function:

 

 # Include  <  String  >  
# Include  <  Iostream  > 
  Using  STD ::  String  ;
  Using  STD: CIN;
  Using  STD: Endl;
  Using  STD: cout;
  Using  STD: boolalpha;
  Using  STD: Getline;
  Int Main ()
{
  String  Line;
  String  Strtmp;
  //  Read line at time until end-of-File  
  Cout  <  "  Enter line:  "  ;
  While (Getline (CIN, line ))
{
Cout  <  Line  <  Endl;
Cout  <     "  Line Length:  "     <  Line. Size ()  <  Endl;
Cout  < Boolalpha  <  Line. Empty ();
Cout  <     "  The sixth character in the string:  "     <  Line [  5  ]  <  Endl;  //  The sixth character in the output string (starting from 0) 
  Cout  <  "  Enter strtmp:  "  ;
CIN  >  Strtmp;
Cout  <     "  Strtmp + line:  "     < Strtmp  +  Line  <  Endl;
Strtmp  =  Line;
Cout  <  Strtmp  <  Endl;
Cout  <     "  Is strtmp equal to line?  "    <  Boolalpha  <  (Strtmp  =  Line)  <  Endl;
Cout  <  "  Enter line:  "  ;
}
  Return     0 ;
} 

(3)StringProcessing of characters in an object:

Isalnum (c)IfCIf it is a letter or number, it isTrue.

Isalpha (c)IfCIf it is a letter, it isTrue.

Iscntrl (c)IfCIs a control character, it isTrue

Isdigit (c)IfCIf it is a number, it isTrue.

Isgraph (c)IfCIt is not a space, but printable, it isTrue.

Islower (c)IfCIf it is a lowercase letter, it isTrue.

Isprint (c)IfCIs a printable character, it isTrue.

Ispunct (c)IfCIs a punctuation, thenTrue.

Isspace (c)IfCIs a blank character, it isTrue.

Isupper (c)IfCIs a capital letter, thenTrue.

Isxdigit (c)If yesCHexadecimal numberTrue.

Tolower (c)IfCReturns lowercase letters. Otherwise, the return value is directlyC.

Toupper (c)IfCIf it is a lower-case letter, it is returned in the upper-case letter format. Otherwise, it is returned directly.C.

Similarly, let's look at an example of using the above function:

 

 # Include  <  String >  
# Include  <  Iostream  >  
  Using  STD ::  String  ;
  Using  STD: CIN;
  Using  STD: Endl;
  Using  STD: cout;
  Using STD: boolalpha;
  Int  Main ()
{
  String  Line;
Cout  <  "  Enter line:  "  ;
  While  (CIN  >  Line)
{
  Bool  TMP;
TMP =  Isalnum (line [  0  ]); // All functions correspond to the above
Cout  <  Boolalpha  <  TMP  <  Endl;
TMP  =  Isalpha (line [  1  ]);
Cout  <  Boolalpha <  TMP  <  Endl;
TMP  =  Iscntrl (line [  2  ]);
Cout  <  Boolalpha  <  TMP  <  Endl;
TMP  =  Isdigit (line [ 3  ]);
Cout  <  Boolalpha  <  TMP  <  Endl;
TMP  =  Islower (line [  4  ]);
Cout  <  Boolalpha  <  TMP <  Endl;
TMP  =  Isprint (line [  5  ]);
Cout  <  Boolalpha  <  TMP  <  Endl;
TMP  =  Ispunct (line [  6  ]);
Cout <  Boolalpha  <  TMP  <  Endl;
TMP  =  Isspace (line [  8  ]);
Cout  <  Boolalpha  <  TMP  <  Endl;
 String  Strtmp;
  For  (  Int  I  =     0  ; I  <     10  ; I  ++  )
{
Strtmp [I]  = Toupper (line [I]);
Cout  <  Strtmp [I];
}
Cout  <  Endl;
Cout  <  "  Enter line:  "  ;
}
  Return     0  ;  } 

To be continued ...................