.pdf

IBM Research – Zurich
Business Integration Technologies
C++ (2.Vorlesung)
Grundlagen
Thomas Gschwind <thg at zurich.…>
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Agenda
Separate Compilation
– Variables
– Routines (Functions & Operators)
– Types (Structures, Classes)
Standard Library
2
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Separate Compilation
Why?
Having only one source file is unrealistic
Break the code up into its logical structure
Reduction of compile time
– Only changed parts need to be recompiled
How?
Use multiple source files
Need to know what information about functions and variables
“used” from other files
3
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Separate Compilation in Java
Each Java file is compiled into a class file
If a Java class invokes a method of another class, the compiler consults the
class file to
–
–
–
–
Determine whether the class provides the requested method
Determine whether a class file implements a given interface
etc.
Hence, the .class file contains the entire interface
That’s why in Java, the compiler needs the class path
Finally, all class files are loaded by the Java Virtual Machine (and linked)
Java source code can be relatively well reconstructed from .class file
(see jad, the java decompiler)
4
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Some Java Trivia
public class Const {
public static final String msg="Hello World!"; }
public class Cool {
public static void main(String[] args) {
System.out.println(Const.msg); } }
5
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Some Java Trivia
public class Const {
public static final String msg="Hello World!"; }
public class Cool {
public static void main(String[] args) {
System.out.println(Const.msg); } }
Now compile both Java files and run Cool
Change the msg in Const.java, recompile Const.java, and run
Cool
6
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Some Java Trivia
public class Const {
public static final String msg="Hello World!"; }
public class Cool {
public static void main(String[] args) {
System.out.println(Const.msg); } }
Now compile both Java files and run Cool
Change the msg in Const.java, recompile Const.java, and run
Cool
Cool still prints the old message! Why?
– javac inlines constants
– And according to the Java specification that’s legal
7
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Separate Compilation in C++
By convention, each source file is compiled into an object file
Object files provide minimum necessary to execute the code
Object files do not provide enough information for the compiler
to identify
– Functions provided by another compilation unit
– Layout of a user-defined type
Object files are not used during the compilation
– C++ and C use “header” files to store the interfaces of the object file
– These files need to be supplied by the developer
In C/C++, we have the include path instead
8
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Header Files
C++ uses so-called header files for separate compilation
The header file can be viewed as the object file’s interface
Header files are another encapsulation mechanism
– They describe the interface(s) provided by the object files
– Describe everything that should be exported to other compilation units
“Everything” that should not be exported stays in the C file
– Except for a few exceptions
9
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Header Files – the truth
Declaration
– Variables and function names
– Types
Definition
– “Implementation”
– Memory allocation & Initialization (well, mostly)
10
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Variables
Variables that are global to the entire project should be declared
as extern in the header file
(avoid unless the variables are constant)
Only constant variables can be initialized in the header file
11
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Example
How can we split this file?
One file for variables, one for main?
#include <cstdlib>
#include <iostream>
vars.cc
using namespace std;
const double pi=3.141596;
const double primes[]={2, 3, 5, …, 1234567891};
int my_dumb_global_variable=17;
void main(int argc, char *argv[]) {
int a1=atoi(argv[1]), a2=atoi(argv[2]);
cout << arg << "^2*pi=" << a1*a2*pi << endl;
cout << "e=" << e << endl;
}
12
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
vars.h
Variables
#ifndef VARS_H_
#define VARS_H_
const double pi=3.141596;
extern const int[] primes;
extern int my_dumb_global_variable;
#endif
vars.cc
#include "vars.h"
13
const int primes[]={2, 3, 5, …, 1234567891};
int my_dumb_global_variable=17;
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
vars.h
Variables
if VARS_H_ is not
defined process the
following lines
#ifndef VARS_H_
define _VARS_H
#define VARS_H_
extern int my_dumb_global_variable;
end the last open
extern const double e;
#if… section
const double pi=3.141596;
This pattern ensures that
#endif
header files won’t be
processed multiple times
vars.cc
#include "vars.h"
14
Process the file
“vars.h”
int my_dumb_global_variable=17;
const double e=2.718281;
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Functions
The signature of the function needs to be included in the header
(for type checking and parameter passing)
inline functions should go here if they should be inlined globally
15
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Functions
#include <cstdlib>
#include <iostream>
using namespace std;
void swap(int &a, int &b) {
// definition
int c=a; a=b; b=c; }
int gcf(int a, int b) {
// definition
if (a<b) swap(a,b);
while (b!=0) { a=a-b; if (a<b) swap(a,b); }
return a; }
inline int lcm(int a, int b) {
// declaration & definition
return (a/gcf(a,b))*b; }
void main(int argc, char *argv[]) {
int a1=atoi(argv[1]), a2=atoi(argv[2]);
cout << arg << "^2*pi=" << a1*a2*pi << endl;
cout << "e=" << e << endl;
}
16
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
util.h
Functions
#ifndef UTIL_H_
#define UTIL_H_
void swap(int &a, int &b);
int gcf(int a, int b);
inline int lcm(int a, int b) {
return (a/gcf(a,b))*b;
}
#endif
// declaration
// declaration
// declaration & definition
util.cc
#include "util.h"
void swap(int &a, int &b) {
// definition
int c=a; a=b; b=c;
}
int gcf(int a, int b) {
// definition
if (a<b) swap(a,b);
while (b!=0) { a=a-b; if (a<b) swap(a,b); }
return a;
}
17
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Classes and Structures
All user-defined types must be in the header file
(typedefs, structures, classes)
Typedefs not otherwise available
Need to know the size and layout of structures (& classes)
Exception
– Types that are only used In the file where they are declared
18
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
fraction.h
Classes and Structures (cont’d)
struct fraction {
// type definition
int c; int d;
fraction(int cntr=0, int denom=1) : c(cntr), d(denom) {}};
fraction operator*(const fraction &a, const fraction &b);
fraction operator/(const fraction &a, fraction b);
fraction.cc
#include "fraction.h"
#include "util.h"
fraction operator*(const fraction &a, const fraction &b) {
fraction r;
int f1=gcf(a.c,b.d), f2=gcf(b.c,a.d);
r.c=(a.c/f1)*(b.c/f2);
r.d=(a.d/f2)*(b.d/f1);
return r; }
fraction operator/(const fraction &a, fraction b) {
swap(b.c,b.d); return a*b; }
19
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
fraction.cc
fraction.h
Classes and Structures (A variation)
20
struct fraction {
// type definition
int c; int d;
fraction(int cntr=0, int denom=1) : c(cntr), d(denom) {}
fraction operator*(const fraction &b);
fraction operator/(fraction b) {
swap(b.c, b.d); return (*this)*b;
}
};
#include "fraction.h"
#include "util.h"
fraction::fraction operator*(const fraction &b) {
fraction r;
int f1=gcf(this->c,b.d), f2=gcf(b.c,this->d);
r.c=(this->c/f1)*(b.c/f2);
r.d=(this->d/f2)*(b.d/f1);
return r; }
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
gcf & lcm main program
main.cc
#include
#include
#include
#include
#include
<stdlib.h>
<iostream>
"fraction.h"
"util.h"
"vars.h"
Hint: Include the system
headers first and then
your own ones.
void main(int argc, char *argv[]) {
int arg=atoi(argv[1]);
cout << arg << "^2*pi=" << arg*arg*pi << endl;
cout << "e=" << e << endl;
cout << gcf(atoi(argv[1]), atoi(argv[2])) << endl;
cout << lcm(atoi(argv[1]), atoi(argv[2])) << endl;
… // making use of our fraction data type
}
21
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Compilation and Dependencies
Include all header files you need
Compile each file
Take care of the dependencies in the Makefile
– If a header file changes the type or layout of a variable, function, or
structure may have changed
– Need to recompile every .cc file that includes these header files
Generating the dependencies (with GNU g++)
– Check out gcc’s various -M compile options
– The GNU java compiler can do this also for Java files
22
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Makefile
all: main
Makefile
main: main.o fraction.o util.o vars.o
g++ -o main main.o fraction.o util.o vars.o
main.o: main.cc fraction.h util.h vars.h
g++ -c main.cc
fraction.o: fraction.cc fraction.h util.h
g++ -c fraction.cc
util.o: util.cc util.h
g++ -c util.cc
vars.o: vars.cc vars.h
g++ -c vars.cc
23
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Makefile
main.cc
fraction.cc
main.o
fraction.o
fraction.h
util.cc
util.o
main
util.h
vars.cc
vars.h
vars.o
compile
link
Java does not have this step. It
provides class loaders which are
similar to the loader/dynamic linker.
24
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Tools to look into object files
nm: list symbols in an object file or program
– Defined, undefined, which section, etc.
ldd, otool –L: list libraries needed by an object file
25
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Makefiles (made easy)
Probably GNU make dependent
CFLAGS=...
CFLAGS+=-Wall -Wextra -Werror
OBJS=main.o
OBJS+=fraction.o ...
# "main" file
# others…
all: main
clean:
rm -f main *.o
distclean: clean
rm -f .depend/*.d
rm -f *~
26
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Makefiles (cont’d)
-include $(addprefix .depend/,$(OBJS:.o=.d))
%.o: %.c
gcc $(CFLAGS) -c -o $@ $*.c
@gcc -MM $(CFLAGS) -c $*.c >.depend/$*.d
main: $(OBJS)
ld $(LDFLAGS) -o $@ $(OBJS)
27
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Compilation & Execution
*shell*
[[email protected] ak3-01]$ make
…
[[email protected] ak3-01]$ ./main 91 49
91^2*pi=26015.556476
e=2.718281
7
637
…
[[email protected] ak3-01]$
28
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Agenda
Separate Compilation
– Variables
– Routines
– User-defined types (structures, classes)
Standard Library
29
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
The Standard Library
Basic Input & Output
Strings
Containers
Iterators
A good overview of the classes and its API can be found here:
http://www.cppreference.com/
No significant program is written in just a
bare programming language.
Bjarne Stroustrup
30
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Basic Input & Output
File streams <fstream>
– ifstream, ofstream, fstream
String streams <sstream>
– istringstream, ostringstream, stringstream
Functions
– >>, get, getline, ignore, read, gcount
– <<, write
31
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
In- & Output (cont‘d)
int main(int argc, char *argv[]) {
char first[256], mi, street[256];
string last, city;
test.cc
// read
cout <<
cout <<
cout <<
a word terminated by whitespace
"First Name? "; cin >> first;
"Middle Initial? "; cin >> mi;
"Last Name? "; cin >> last;
// read a line terminated by newline
cin.ignore(256,'\n');
cout << "Address? "; cin.get(street,256);
cout << "City? "; getline(cin,city,'\n');
// suspect
// ok
// ok
// ok
// suspect
// ok
cout << "Hello, " << first << "!" << endl;
cout << "I like " << city << "!" << endl;
}
32
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Unix to DOS Converter
unix2dos.cc
#include <iostream>
#include <fstream>
int main(int argc, char *argv[]) {
ifstream ifs(argv[1]);
ofstream ofs(argv[2]);
Ignores
char c;
whitespace
for(;;) {
ifs >> c;
if(!ifs.good()) break;
if(c=='\n') ofs << "\r\n";
else ofs << c;
}
}
33
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Unix to DOS Converter II
todos2.cc
#include <iostream>
#include <fstream>
int main(int argc, char *argv[]) {
ifstream ifs(argv[1]);
ofstream ofs(argv[2]);
char c;
for(;;) {
ifs.get(c);
if(!ifs.good()) break;
if(c=='\n') ofs << "\r\n";
else ofs << c;
}
}
34
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
String Functions
#include <string>
…
int main(int argc, char *argv[]) {
string h("Hello"), w("World"), s;
w.append("!");
cout << w[5] << w.at(5) << endl;
w.insert(w.begin(), h.rbegin(), h.rend());
cout << w << endl;
w.replace(4,2,"H W");
cout << w << endl;
cout << "Enter your name: ";
getline(cin, s);
cout << h << " " << s << endl;
return 0;
}
35
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Container
Provide different data structures
Abstraction of a memory area
User-defined allocators
Can be accessed using iterators
36
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Containers (Overview)
Sequence Containers
– vector<T>, list<T>, deque<T>
Associative Containers
– map<K,V>, multimap<K,V>
– set<K>, multiset<K>
Sequence Container Adapters
– stack<T,C>
– queue<T,C>, priority_queue<T,C>
37
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Complexity Guarantees
[]
vector
38
Insert/Remove Elements
Begin
O(1)
Iterator
Middle
End
O(n)+
O(1)+
Ran
O(1)
Bi
list
O(1)
O(1)
forward_list
O(1)
O(1)
O(1)
O(n)
For
deque
O(1)
map
O(log(n))
O(log(n))+
Bi
unordered_map
O(1)+
O(1)+
For
string
O(1)
O(n)+
O(n)+
Th. Gschwind. Fortgeschrittene Programmierung in C++.
O(1)
O(n)
Ran
Ran
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
A Simple vector Example
#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main(int argc, char *argv[]) {
vector<string> playlist;
playlist.push_back("1. Have A Nice Day");
playlist.push_back("2. I Want To Be Loved");
playlist.push_back("3. Welcome To Wherever You Are");
playlist.push_back("4. Who Says You Can't Go Home");
playlist.push_back("5. Last Man Standing");
...
39
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Iterators
Define a sequence over the elements in a container
vector:
40
T*
#0 #1 #2 #3 #4 #5 #6 #7 #8 #9
Iterator1:
T *p
Iterator2:
{ T* start; int pos; }
Th. Gschwind. Fortgeschrittene Programmierung in C++.
…
#n
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
More on Iterators (cont‘d)
List:
lnk*
Iterator3:
#0
#1
#2
#3
#4
lnk
lnk
lnk
lnk
lnk
…
lnk *p
Map: nd
Iterator4: ndi p
nd
nd
41
nd
nd
nd
Th. Gschwind. Fortgeschrittene Programmierung in C++.
nd
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
More Java Trivia
... // store playlist in ArrayList playlist
BufferedReader in=new BufferedReader(new InputStreamReader
ListIterator i=playlist.listIterator();
String song="none";
for(;;) {
System.out.println("playing "+song);
String cmd=in.readLine();
if(cmd.equals("quit")) break;
if(cmd.equals("next") && i.hasNext()) {
song=(String)i.next();
} else if(cmd.equals("prev") && i.hasPrevious()) {
song=(String)i.previous();
} else {
System.out.println("unknown command "+cmd);
} } }
42
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
More Java Trivia
... // store playlist in ArrayList playlist
BufferedReader in=new BufferedReader(new InputStreamReader
ListIterator i=playlist.listIterator();
Constantly going
String song="none";
back and forth in the
for(;;) {
playlist will
System.out.println("playing "+song);
repeatedly play the
String cmd=in.readLine();
same song
if(cmd.equals("quit")) break;
if(cmd.equals("next") && i.hasNext()) {
song=(String)i.next();
} else if(cmd.equals("prev") && i.hasPrevious()) {
song=(String)i.previous();
} else {
System.out.println("unknown command "+cmd);
} } }
43
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Iterators the C++ Way
vector<string> playlist;
... // store playlist in ArrayList playlist
vector<string>::iterator fst=playlist.begin(),
cur=fst,
lst=playlist.end();
string cmd;
for(;;) {
if(cur==lst) cout << "playing none" << endl;
else cout << "playing " << *cur << endl;
cin >> cmd;
if(cmd=="quit") break;
if(cmd=="next" && cur!=lst) ++cur;
else if(cmd=="prev" && cur !=fst) --cur;
else cout << "unknown command " << cmd << endl;
}
44
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Different Types of Iterators
Category
output
input
Out
In
For
Bi
Ran
Read
=*p
=*p
=*p
=*p
Access
->
->
->
-> []
*p=
*p=
*p=
++
++
++ --
== !=
== !=
== !=
Abbrev.
Write
*p=
Iteration
++
Compare
45
birandomforward
directional access
Th. Gschwind. Fortgeschrittene Programmierung in C++.
++
-==
!=
+
<
>
+=
-=
<=
>=
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Iterators (Java vs. C++)
Java
C++
Iterator obtained using iterator(), a
ListIterator using listIterator()
Iterator returned through begin()
and end() or rbegin() and rend()
Iterator points between elements
=> current element cannot be
accessed multiple times
Iterator points to the element
=> current element can be returned
multiple times
Iterator knows about first and last
position
Iterator does not know about begin
and end; second iterator is used for
this purpose
=> flexibility as side effect; routine
can iterate over any segment of the
container
=> inflexible since routines cannot
be easily changed to iterate over a
part of the container
If bounds are exceeded, an
exception is raised
46
If bounds are exceeded, undefined
behavior, probably a “segmentation
violation”
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Iterators (Java vs. C++)
C++
Iterator points to the elements (green)
Repeatedly going forward and backward gives alternating
elements
vector:
#0 #1 #2 #3 #4 #5 #6 #7 #8 #9
…
#n
Java
Iterator points between the elements (red)
Repeatedly going forward and backward gives the same
element
47
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Summary
Separate Compilation
– Variables
– Routines (Functions & Operators)
– Types (Structures, Classes)
Standard Library
48
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Exercise 1
Which of these lines belong into the header file? Why?
char ch;
string s;
extern int error_number;
static double sq(double);
int count=1;
const double pi=3.2; // according to Indiana Pi Bill
struct fraction { int c; int d; };
char *name="It's me";
char *prog[]={"echo","hello","world!",NULL};
extern "C" void c_swap(int *a, int *b);
double sqrt(double);
void swap(int &a, int &b) { int c=a; a=b; b=c; }
namespace NS { int a; }
struct user;
49
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Exercise 2
Separate compilation
– Split the complex data type program into header file(s) and C++ file(s)
– Write a Makefile and compile the above
50
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Exercise 3
Implement an RPN (Reverse Polish Notation Calculator)
–
–
–
–
When the user enters ‘q’ the program terminates
When the user enters ‘n’ followed by a number, it is put on the stack
When the user enters ‘d’ the last number is removed from the stack
When the user enters ‘+’, ‘-’, ‘*’, ‘/’, the calculator takes the last two
numbers from the stack applies the operation to the numbers and puts the
result on the stack
– Use the std::vector container and its iterator!
51
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Exercise 3 – An Example (user input in bold)
Command:
1: 2
2: 4
3: 3
Command:
1: 2
2: 12
Command:
1: -10
Command:
1: -5
Command:
Command:
52
n 2 n 4 n 3
*
n 2 /
d
q
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Exercise 4
Simple Spell Checker
Implement a simple spell checker. The spell checker takes two
files as command line arguments, a dictionary file containing a
list of correctly spelled words and a file whose content is to be
checked. Upon startup, your program stores the words
contained in the dictionary file in a set<string>. Then it reads
every word in the file to spell check, checks whether each word
is correctly spelled (ie contained in the dictionary file) and if not
displays it on cout.
53
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
correctly
spelled
words
are
stored
in
the
dictionary
a comprehensive dictionary
is important.
text.txt
dict.txt
Exercise 4 – An Example
C:\> check dict.txt text.txt
a
comprehensive
is
important
C:\>
54
Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
IBM Research – Zurich
Business Integration Technologies
Next Lecture
C++ and Inheritance
Have fun solving the examples!
See you next week!
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Th. Gschwind. Fortgeschrittene Programmierung in C++.
© 2014 IBM Corporation
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