C ++ string

C ++ string class

The C ++ standard template library (STL) contains a string class that is used in several computer science classes. In order to use the string class you shoshould include the following statements:
# Include <string>
Using STD: string;

The following examples assume these declarations and initial values for each:

String S = "ABC def ABC ";
String S2 = "ABCDE uvwxyz ";
Char C;
Char ch [] = "ABA Daba do ";
Char * CP = CH;
Unsigned int I;

Stream Input	Cin> S;	Changes the value of S to the value read in. The value stops at whitespace.
Stream output	Cout <s;	Writes the string to the specified output stream.
Line Input	Getline (CIN, S );	Reads everything up to the next newline character and puts the result into the specified string variable.
Assignment	S = S2; S = "ABC "; S = CH; S = CP;	A string literal or a string variable or a character array can be assigned to a string variable. The last two assignments have the same effect.
Subscript	S [1] = 'C '; C = s [1];	Changes s to equal "ACC def ABC" Sets C to 'B'. The subscript operator returns a char value, not a string value.
Length	I = S. Length (); I = S. Size ();	Either example sets I to the current length of the string s
Empty?	If (S. Empty () I ++; If (S == "") I ++;	Both examples Add 1 to I if string S is now empty
Relational operators	If (S <S2) I ++;	Uses ASCII code to determine which string is smaller. Here the condition is true because a space comes before letter d
Concatenation	S2 = S2 + "X "; S2 + = "X ";	Both examples add X to the end of S2
Substring	S = s2.substr (1, 4 ); S = s2.substr (1, 50 );	The first example starts in position 1 of S2 and takes 4 characters, setting s to "bcde ". in the second example, S is set to "bcde uvwxyz ". if the length specified is longer than the remaining number of characters, the rest of the string is used. the first position in a string is position 0.
Substring replace	S. Replace (4,3, "x ");	Replaces the three characters of s beginning in position 4 with the character X. Variable S is set to "ABC x ABC ".
Substring Removal	S. Erase (4, 5 ); S. Erase (4 );	Removes the five characters starting in position 4 of S. The new value of S is "abc bc ". Remove from position 4 to end of string. The new value of S is "ABC ".
Character array to string	S = CH;	Converts character array ch into string S.
String to character array	CP = S. c_str ();	Pointer CP points to a character array with the same characters as S.
Pattern Matching	I = S. Find ("AB", 4 ); If (S. rfind ("AB", 4 )! = String: NPOs) Cout <"yes" <Endl;	The first example returns the position of the substring "AB" starting the search in position 4. sets I to 8. The find and rfind functions return the unsigned intString: NPOsIf substring not found. The second example searches from right to left starting at position 4. Since the substring is found, the word yes is printed.