Einführung in die Nutzung der
Standard Template Library (STL)
Literatur:
(Amme) - Ammeraal, L.: STL for C++-Programmers;
Chichester: Wiley, 1997
(Brey) - Breymann, U.: C++ Einfüfung und professionelle Programmierung;
München: Hanser, 2007 (9. Auflage)
#include <iostream.h>
int main()
{
int vektor[1000]; // Maximal 1000 Elemente !!
int i = 0, j;
int x;
cout << "Enter positive integers, followed by 0:\n";
while (cin >> x, x != 0)
{
vektor[i] = x;
i++;
}
cout << endl;
for ( j = 0; j < i; j++)
cout << vektor[j] << " ";
cout << endl;
return 0;
}
// readwr.c: Reading and writing a variable number of
// nonzero integers (followed in the input by 0).
// From: Ammeraal, L. (1997) STL for C++ Programmers,
// Chichester: John Wiley.
#include <iostream>
//fuer g++ erst ab Version 2.8 verfuegbar
#include <vector.h>
int main()
{ vector<int> v;
int x;
cout << "Enter positive integers, followed by 0:\n";
while (cin >> x, x != 0)
v.push_back(x);
vector<int>::iterator i;
for (i=v.begin(); i != v.end(); ++i)
cout << *i << " ";
cout << endl;
return 0;
}
// readwrd.c: Reading and writing a variable number of
// nonzero integers (followed in the input by 0).
// From: Ammeraal, L. (1997) STL for C++ Programmers,
// Chichester: John Wiley.
#include <iostream.h>
#include <deque>
int main()
{ deque<int> v;
int x;
cout << "Enter positive integers, followed by 0:\n";
while (cin >> x, x != 0)
v.push_back(x);
deque<int>::iterator i;
for (i=v.begin(); i != v.end(); ++i)
cout << *i << " ";
cout << endl;
return 0;
}
Der Nutzer bemerkt keinen Unterschied zwischen den drei möglich Versionen, Unterschiede bestehen aber in der internen Darstellung und in den möglichen Operationen:
| Operation | Funktion | vector | list | deque |
| Einfügen am Ende | push_back | j | j | j |
| Löschen am Ende | pop_back | j | j | j |
| Einfügen am Anfang | push_front | n | j | j |
| Löschen am Anfang | pop_front | n | j | j |
| Einfügen irgendwo | insert | (j) | j | (j) |
| Löschen irgendwo | erase | (j) | j | (j) |
| Sortieren | sort | j | n | j |
Im Folgenden soll ein Beispiel für Einfüge- und Löschoperationen in Listen angegeben werden:
// insdel.cpp: Insertions and deletions in a list.
// From: Ammeraal, L. (1997) STL for C++ Programmers,
// Chichester: John Wiley.
#include <iostream>
#include <list>
void showlist(const char *str, const list<int> &L)
{ list<int>::const_iterator i;
cout << str << endl << " ";
for (i=L.begin(); i != L.end(); ++i)
cout << *i << " ";
cout << endl;
}
int main()
{ list<int> L;
int x;
cout << "Enter positive integers, followed by 0:\n";
while (cin >> x, x != 0)
L.push_back(x);
showlist("Initial list:", L);
L.push_front(123);
showlist("After inserting 123 at the beginning:", L);
list<int>::iterator i = L.begin();
L.insert(++i, 456);
showlist(
"After inserting 456 at the second position:", L);
i = L.end();
L.insert(--i, 999);
showlist(
"After inserting 999 just before the end:", L);
i = L.begin(); x = *i;
L.pop_front();
cout << "Deleted at the beginning: " << x << endl;
showlist("After this deletion:", L);
i = L.end(); x = *--i;
L.pop_back();
cout << "Deleted at the end: " << x << endl;
showlist("After this deletion:", L);
i = L.begin();
x = *++i; cout << "To be deleted: " << x << endl;
L.erase(i);
showlist("After this deletion (of second element):",
L);
return 0;
}
// sort1.cpp: Sorting a vector.
// From: Ammeraal, L. (1997) STL for C++ Programmers,
// Chichester: John Wiley.
#include <iostream>
#include <vector>
#include <algorithm>
int main()
{ vector<int> v;
int x;
cout << "Enter positive integers, followed by 0:\n";
while (cin >> x, x != 0) v.push_back(x);
vector<int>::iterator i;
cout << "Before sorting :\n";
for (i=v.begin(); i != v.end(); ++i)
cout << *i << " ";
cout << endl;
sort(v.begin(), v.end());
cout << "After sorting: \n";
for (i=v.begin(); i != v.end(); ++i)
cout << *i << " ";
cout << endl;
return 0;
}
Die Sortierung wird durch den Befehl:
sort(v.begin(), v.end());ausgeführt.
#include <algorithm>notwendig, diese Includedirektive wird aber implizit durch
#include <vector>mit eingebunden
int a[10], x, n = 0, *p; ..... while (cin >> x, x != 0 && n < 10) a[n++] = x; sort(a, a+n);
....
cin >> x;
vector<int>::iterator i =
find(v.begin(), v.end(), x);
if (i == v.end())
cout << "Not found\n";
else
{ cout << "Found";
....
....
{ int a[4] = {10, 20, 30, 40};
vector<int> v(a, a+4);
list<int> L(4); // A list of 4 elements
copy(v.begin(), v.end(), L.begin()); // copying 4 elements to L
list<int>::iterator i;
for (i=L.begin(); i != L.end(); ++i)
cout << *i << " "; // Output: 10 20 30 40
.....
Problem: Im obigen Beispiel werden Elemente der Zielliste L überschrieben, was manchmal (häufig) nicht gewünscht ist. Lösung: Nutzung eines inserter
....
{ int a[4] = {10, 20, 30, 40};
vector<int> v(a, a+4);
list<int> L(5, 123); // A list of 5 elements, all are 123
list<int>::iterator i = L.begin();
++i; ++i;
copy(v.begin(), v.end(), inserter(L, i));
....
....
vector<int> a(5);
a[0] = 2; a[1] = 3; a[2] = 8;
a[3] = 20; a[4] = 25;
int b[6] = {7, 9, 23, 28, 30, 33};
list<int> c; // List c is initially empty
merge(a.begin(), a.end(), b, b+6,
inserter(c, c.begin()));
....
// Phil Ottewell's STL Course - http://www.yrl.co.uk/~phil/stl/stl.htmlx
//
// Example 5.1 � Phil Ottewell 1997 <phil@yrl.co.uk>
//
// Purpose:
// Demonstrate use of standard string class
// ANSI C Headers
#include <stdlib.h>
// C++ STL Headers
#include <algorithm>
#include <iostream>
#include <string>
#ifdef _WIN32
using namespace std;
#endif
int main( int argc, char *argv[] )
{
size_t ip;
string needle = "needle"; // Initialize with C style string literal
string line("my string"); // Ditto
string haystack(line,0,3); // Initialize with another string starting
// at element 3, i.e. "string"
string string3(line,0,2); // Initialize with first 2 characters of
// line, i.e. "my"
string s1; // INITIALIZING with single character, e.g.
string s2; // = 'A' or ('A') or an integer NOT ALLOWED
// These will currently have .length() of zero
string dashes(80,'-'); // You can initialize using a character like
// this, and character ASSIGNMENT is legal
char old_c_string[64];
// Concatenation using + operator
s1 = "Now is the Winter ";
s2 = "of our discontent made Summer";
cout << "s1 = \"" << s1 << "\"," << "s2 = \"" << s2 << "\"\n"
<< "s1 + s2 = \"" << s1 + s2 << "\"" << endl << dashes << endl;
// Find a substring in a string
haystack = "Where is that " + needle + ", eh ?";
cout << "haystack = \"" << haystack << "\"" << endl;
ip = haystack.find(needle);
// Use substr function to get substring - use string::npos (the "too large"
// character count) to get the rest of the string
cout << "ip = haystack.find(needle) found \""
<< haystack.substr(ip,string::npos )
<< "\" at position ip = " << ip << endl << dashes << endl;
// Demonstrate use of Algorithms with strings
line = "Naomi, sex at noon taxes, I moan";
cout << line << " [Algorithm: reverse(line.begin(),line.end())]" << endl;
reverse( line.begin(), line.end() );
cout << line << " [line.length() = " << line.length() << "]" << endl
<< dashes << endl;
// Passing a string to a function requiring a C style string
line = "copyright";
strncpy( old_c_string, line.c_str() , sizeof(old_c_string)-1 );
old_c_string[sizeof(old_c_string)-1] = '\0';
cout << "strncpy \"" << line << "\" to c string which now contains \""
<< old_c_string << "\"" << endl << dashes << endl;
// Insert into a string
s1 = "piggy middle";
s2 = "in the ";
cout << "s1 = \"" << s1 << "\", s2 = \"" << s2 << "\"" << endl;
s1.insert(6,s2); // Insert s2 in s1
cout << "s1.insert(6,s2) = " << s1 << endl << dashes << endl;
// Erase
cout << "[Use s1.erase(ip,4) to get rid of \"the \"]" << endl;
ip = s1.find("the");
if ( ip != string::npos ) s1.erase( ip, 4 ); // Note check on ::npos
cout << s1 << endl << dashes << endl;
// Replace
cout << "[Use s1.replace(ip,2,\"is not in the\") to replace "
<< "\"in\" with \"is not in the\"]" << endl;
ip = s1.find("in");
// Note inequality check on string::npos to see if search string was found
if ( ip != string::npos ) s1.replace( ip, 2, "is not in the" );
cout << s1 << endl << dashes << endl;
return( EXIT_SUCCESS );
}
Assoziative Container
#include <map>
| Some Map Access Functions | Purpose |
| begin() | Returns iterator pointing to |
| first element | |
| end() | Returns iterator pointing _after_ |
| last element | |
| swap( , ) | Swap two elements |
| insert( , ) | Insert a new element |
| size() | Number of elements in map |
| max_size() | Maximum possible number of elements |
| in map | |
| empty() | True if map is empty |
| [ ] | Subscript search access operator |
// Beispiel fuer Abbildung (map)
#include<map>
#include<string>
// zur Abkuerzung zwei typedefs
// Vergleichsobjekt: less<long>()
typedef map<long, string> Abbildungstyp;
typedef Abbildungstyp::value_type Wertepaar;
int main()
{
Abbildungstyp Abbildung;
Abbildung.insert( Wertepaar(836361136, "Andreas"));
Abbildung.insert( Wertepaar(274635328, "Bernd"));
Abbildung.insert( Wertepaar(260736622, "Juergen"));
Abbildung.insert( Wertepaar(720002287, "Karin"));
Abbildung.insert( Wertepaar(138373498, "Thomas"));
Abbildung.insert( Wertepaar(135353630, "Uwe"));
// Einfuegen von Xaver wird nicht ausgef�hrt, weil
// der Schluessel schon vorhanden ist.
Abbildung.insert( Wertepaar(720002287, "Xaver"));
/*
Die Ausgabe der Namen ist wegen der unterliegenden
Implementierung nach Nummern sortiert:
*/
cout << "Ausgabe:\n";
Abbildungstyp::iterator iter = Abbildung.begin();
while(iter != Abbildung.end())
{
cout << (*iter).first << ':' // Nummer
<< (*iter).second // Name
<< endl;
++iter;
}
cout << "Ausgabe des Namens nach Eingabe der Nummer\n"
<< "Nummer: ";
long Nummer;
cin >> Nummer;
iter = Abbildung.find(Nummer); // O(log N), siehe Text
if(iter != Abbildung.end())
cout << (*iter).second << ' ' // O(1)
<< Abbildung[Nummer] // O(log N)
<< endl;
else cout << "Nicht gefunden!" << endl;
}
#include <set>Set speichert nur einfache Schlüssel, das heißt der Schlüssel ist der Wert.
| Some Set Access Functions | Purpose |
| begin() | Returns iterator pointing to first |
| element | |
| end() | Returns iterator pointing _after_ |
| last element | |
| swap( , ) | Swap two elements |
| insert( , ) | Insert a new element |
| size() | Number of elements in set |
| max_size() | Maximum possible number of |
| elements in set | |
| empty() | True if set is empty |
// Beispiel fuer Menge (set)
#include<set>
#include<showseq>
int main()
{
int i;
set<int> Menge; // Vergleichsobjekt: less<int>()
for(i = 0; i < 10; i++) Menge.insert(i);
for(i = 0; i < 10; i++) Menge.insert(i); // ohne Wirkung
showSequence(Menge); // 0 1 2 3 4 5 6 7 8 9
/*
Die Anzeige demonstriert, da� die Elemente der Menge wirklich genau
einmal vorkommen. Im folgenden werden Elemente geloescht, wobei in
der ersten Variante zunaechst das Element gesucht wird, um
es dann mit dem gefundenen Iterator zu loeschen. In der zweiten
Variante wird die Loeschung ueber den angegebenen Schl�ssel
vorgenommen.
*/
cout << "Loeschen per Iterator\n"
"Welches Element loeschen? (0..9)" ;
cin >> i;
set<int>::iterator iter = Menge.find(i);
if(iter == Menge.end())
cout << i << " nicht gefunden!\n";
else
{
cout << "Es gibt " << Menge.count(i) // 1
<< "-mal das Element " << i << endl;
Menge.erase(iter);
cout << i << " geloescht!\n";
cout << "Es gibt " << Menge.count(i) // 0
<< "-mal das Element " << i << endl;
}
showSequence(Menge);
}
#include <numeric>