1
4/11/2020
NOT FINISHED!!
MEMO C++. (STL): Standard Template Lib
Mihaela Malita mmalita@anselm.edu
http://cplusplus.com
// File: program.cpp
// Title: Prints integers from 1 to limit
#include <iostream>
using namespace std;
int main ( ) { // always has a main function
int limit, count = 0; //declare type of variable
cout << "Enter an integer? "; //ask
cin >> limit;
//read value
while (i <= limit) {
// counts till 5
cout << i << endl;
i++; // or i = i + 1;
}
// same with a DO
do {
i = i + 1; // or i++;
or i+=1;
cout << i << '\n' ;
} while (i < limit) ; //condition at the end
// same with for
for (int i = 1; i <= limit; i++) {
cout << i << endl;
}
return 0; // always if program is correct 0=true
}
RUN progam.cpp
Compile: program.cpp -> program.obj
Link: program.obj ->program.exe
Execute: >program.exe (independent file)
switch (day) { // day is 0..6
case 0: cout << " day is Sunday";
break;
case 1: cout << " day is Monday";
break;
…
default: cout << " Error day not 0-6";
}
Type bool, bool b=true; // b is true or false
// 0 stands for false. Anything =/= 0 is true
// can use int or bool. Always prefer bool!
cout << boolalpha << b;
// prints true
FORMAT
#include <iomanip>
cout << setiosflags(ios::right)
<< setprecision(3)<<setw(5) << 7.891 ;
isspace(c) ; iscntrl ( c); ispunct( c);
isprint( c);
CONVERSIONS
#include <cstdlib>
double atof(const char *ptr) //
// prints on 2 columns numbers 1-100
double n= atof("2.3"); //alpha to float
for (int i=1 ; i<100 ; i++) {
int atoi(const char *ptr) // int k=atoi("23");
cout << i << ( (i % 2)? '\t' : '\n' ); }
double strtod(const char * s, char **ptr)
\a = beep
\t = tab
\n = new line
getch(); // waits for any character from the keyboard d = strtod("2.3 is a nr", &ptr)
d = 2.3 and cout << ptr // print “ is a nr”
#include "windows.h"
#include <cstring>
Sleep(30); // sleeps 30 millisecs
char *strcat(s1,s2) strncpy(new_s,old_s,size)
Data Types
Size
Range
int strcmp(s1,s2) //0 if s1=s2; n>0 if s1>s2;n<0 else
char
0-256
size_t_strlen(const char *s)
//length of string
int
ARRAYS
unsigned int
0-6535 ( 2 – 1)
const int n=5; // declare const size
short
int A[n] = {0}; //all elements become 0
long
int A[n] ={6,2,1,4,7} //elements take values
unsigned long
0char mystring[] = "programming"; //ends '\0'
double
int B[2][2]= {{1,2},{4,8}}; //initialize matrix 2 x 2
float
Compare arrays – element by element
MATH
#include <cmath>
Operations: + , - , /, *, %
STRING CLASS
sin(0.5)
cos(double)
tan(double)
#include
<string>
exp(4)
pow(3.0 2.0) sqrt(4.0)
string s = "I love C";
// string s("I love C");
log(double)
log10(double)
s
=
s.append(s);
// s-> "I love CI love C"
floor(9.3)
ceil(9.7)
fabs(-8.9)
s
+
=
"great";
same
as
s = s + "great";
RANDOM
cin
>>
s;
//
reads
till
blank
#include <ctime>
//for time()
getline(cin.s); // reads till '\n'
#include <cstdlib>
//for srand()CodeBlocks
s.length();
same as s.size();
srand(time (0));
//does not return a value!
s1.compare(s2);
// s1 > s2 , s1 <s2 or s1 == s2
0<=rand()<=RAND_MAX;
s.substr(7,5);
//
from 7 add 5 from string s
Ex ;produce a random 1-6: int die= rand()%6 +1;
s1.swap(s2); //changes values s1 with s2
s.empty();
// (s.empty() ? "true" : "false")
CHAR CLASS
s.find_first_of("love" ); // returns first index
char c = 'a' ;
s.find_last_of("love" );
char(65)= 'A' ; char(97)= 'a'; // ASCII code
s.find("love" ); /
/returns int (index)
On 1 byte: ASCII code 0-255=pow(2,8)-1
//check
if
there:
if
(
s.find(w)<
s.length() )
char color []=”blue”;
//same as
s.replace(x,1,
"."
);
char color []={'/b', '/l', '/u', '/e', '/0'};
string::npos //last position of sting (till the end)
#include <cctype>
s.insert(3,s2);// inserts at position 3 string s2
isdigit(c); isalpha(c); isalnum(c);
// erase position 30->?
islower(c); isupper(c); tolower ( c); tolower (c ); s.erase(30);
2
VECTOR CLASS FROM STL
#include <vector>
int A[] ={2,3,4,5};
//copy from array A, 3 elements
vector <int> V(A,A+3);
vector <int> V;
//declare V without any size
V.push_back(w);
V.pop_back();
V.front();
V.back();
V.clear();
V.empty();
V.erase(V.begin() + 2); //erase index = 2
V.erase(Ptr);
V.insert(V.begin()+1,7); //inserts 7, V[1] = 7
V.resize(10); // extends size of V
V.swap(X);
// change values
V1 == V2 ;
//COMPARE
V1 > V2;
V1 >=V2; V1 < V2 ; V1 <= V2;
#include <algorithm>
int k = count(V.begin(),V.end(),5);
//counts 5
sort(V.begin(),V.end()) ; //sort ascending order
erase( find(V.begin(),V.end(),w)) // finds/erases w f
random_shuffle(V.begin(),V.end());
// check if it is there, if reach end then NO
if ( find(V.begin(),V.end(),w) == V.end() )
cout << “ not found”;
// print using iterator- pointer
void print ( vector <int> V ) {
for (vector <int>::iterator it = V.begin();
it != V.end() ; p++) {
cout << *it < < '\t';
}
//
prototype
template < typename T >
void print (vector <T> V);
//
function
template < typename T >
void print (vector <T> V) {
for (int i = 0; i < V.size(); i++)
cout << V[i] << '\t';
}
POINTER
int n = 5;
int * ptr = &n;
cout << &n; // 034A26F0 address in RAM
cout << *ptr ; // * dereference operator, prints 5
void func ( int x ) {
//call by value
x = 2 *x; }
// does not modify x
void func ( int &x ) { //call by reference
x = 2 * x; }
//modifies x
fstream ff ("oscar.txt",ios::out|ios::app|ios::in);
OOP-CLASS
//File: Pet.h
#ifndef PET_H
#define PET_H
class Pet {
private:
//data-members
FILES
#include <fstream>
string name;
// WRITE:
int YOB; //year of birth
string filename = "ints.txt";
public:
// functions-methods
ofstream fout ( filename.data() );
Pet(string s=”noName”, int y=0) { //constructor
fout << 2012 ; // write to end of file
name=s; YOB=y;}
fout.close(); //close stream
void setYOB (int n){
//setter
// Open a file and append
YOB = (n>=2000 && n<2014)? n :0;}
int getYOB(){ return YOB; }
//getter
ofstream fout(filename.data(), ios::app);
// READ: when you know the file name
void print(){ cout<< name <<’\t’ << YOB ; }
ifstream fin( "data.txt”);
};
if ( !inFile ) { // check if file exists
#endif
//File: programPet.cpp
cerr << "Unable to open \"data.txt\".\n";
exit( EXIT_FAILURE ); // exit(1) | return 1; #include <iostream>
using namespace std; //order is important
}
while ( !fin.eof() ) { // tests end of file
#include "Pet.h" // last include the header file
fin >> x; // reads from stream
int main () {
// sets and prints time
Pet X (“Coop”,2010); //declare object
cout << x << endl;
} fin.close(); //close stream
t.setYOB(2011);
//instantiates YOB
// read a char x including blank: fin.get( x );
t.print();
cout << t.getYOB();
// read a line (till endl):
getline(fin,x,'\n');
return 0;
fstream fin (f.data(),ios::in); // open for reading
}
if ( fin.fail() ) {
// check if file exists
INHERITANCE
cout << "\nError";
return -1;}
printFile(fin);
#include "Pet.h"
fin.clear();
// reset eof for next input
class Cat : public Pet { //Cat is a Pet
in.seekg(0);
// move to beginning of file
public:
// functions-methods
printFile(fin);
//call
Cat();
// constructor - same name
void speak(){ cout << "meou";}
void printFile( fstream & fin ){
void print(){ Pet::print();}
string s;
while(! fin.eof() ){
};
// in main() – Cat X; X.setName(“Garfield”);
getline(fin,s);
X.print();
cout<< s << endl;
}}
// open for more operations (flags)