programming fundamentals

The new Operator
• float* p;
• only allocate memory for a pointer
• *p=3.1459
• One way to avoid this is assign
memory using the key word new

The new Operator
• int main(){
• float*p;
• p=new float;//create unnamed
memory
• *p=3.14159;
• cout<<p<<" "<<*p;
• getch();
• }

The delete Operator
• The delete operator reverse the
operation of new operator
• It de-allocate the memory reserved
by the new operator
• float*p=new float;
• *p=3.1459;
• delete p;
• *p=3.44; //Wrong

Pointer to pointer(**)
• int main(){
• int n=44;
• int* pn=&n;
• int** ppn=&pn;
• cout<<"*pn="<<*pn<<"
ppn="<<**ppn;
• getch();
• }
44
pn
ppn

Character Pointers
• int main(){
• char *p="This is a text";
• // Exactly Same As
• char a[100]="This is a text";
• cout<<p;
• // Same As
• cout<<endl<<a;
• getch();
• return 0;
• }

String Manipulation
Functions
• char * strcpy (char *s1 , const char *s2 ) ;
Copies the string s2 into the character array s1.The
value of s1 returned.
• char * strncpy ( char *s1 , char *s2 , int n ) ;
copies atmost n characters
• char * strcat (char *s1 , char *s2 ) ;
Appends the string s2 to the string s1.the first
character of s2 overwrite the null character of s1.the
value of s1 is returned.
• char * strncat ( char *s1 , char *s2 , int n ) ;

Comparison Functions
• int strcmp (const char *s1 , const char *s2 )
Compares the string s1 with s2.The function return a
value zero,less than zero or greater than zero.
• int strncmp ( const char *s1 , const char *s2 ,
int n ) ;
• int strlen ( const char *s ) ;

• #include<iostream>
• #include<string>
• void main(){
• char x[100]={"Happy Birthday"};
• char y[100],z[100];
• strncpy(y,x,5);
• strcpy(z,y);
• strcat(x," to you");
• cout<<"nThe x string:"<<x;
•

• if(strcmp(x,y)==0)
• cout<<"n string x and y are equal";
• else
• cout<<"n string x and y are not equal";
•
• if(strcmp(z,y)==0)
• cout<<"n string z and y are equal";
• else
• cout<<"n string z and y are not equal";
• getch();
• }

• void main(){
• char *p;
• char a[100],b[15];
• cout<<"Plz Enter a string:";
• gets(a);
• cout<<"What u want find";
• gets(b);
• p=strtok(a," ");
• while(p!=NULL){
• if(strcmp(b,p)==0)
• cout<<"n The string" "<<p<< ""is
found:";
• p=strtok(NULL," ");
• }
• getch();

Structures
• User Defined Data type
• Used to define objects having same
properties

Structure definition
• struct Student {
• char name [ 60 ] ;
• char address [ 100 ] ;
• double gpa ;
• } ;
Keyword
Structure
name

• Student s1 , s2 , s3 ;
• Student ali, waqas;
Structure Name
Variable Name
Variables of Structure

Structure
• Structure can have pointer data
type as member
• Structure can have other structure
as member data type
• Structure can not have same
structure as data type

Structure
• struct address {
• char streetAddress [ 100 ] ;
• char *city ;
• char country [ 30 ] ;
• }

Structure
• address add ;
• double gpa ;
• } s1 , s2 , s3 ;

Structure Variables
Variables of type structure
Pointers to Structure
Array of Structure

Structures
• Student a,b,c;
• Student s [ 100 ] ;
• Student *sPtr ;

Example 2
• char course [ 128 ] ;
• int age ;
• int year ;
• } ;

Initializing Structures
Student s1 = { “Amir”,“cs201”,19, 2002 } ;
Name Course age Year

• s1.name ;
• s1.course ;
• s1.age ;
• s1.year ;

• s1.age = 20 ;
• s1.name = “Abbas Ali ” ; //Wrong
• strcpy ( s1.name , “Abbas Ali ” ) ;
• s1.year=2000;

Accessing structure
members
• cout << s1.name ;
• cout << s1.course ;
• cout << s1.age ;
• cout << s1.year ;

• #include<string>
• struct Student{
• char name [ 64 ];
• char course [ 128 ];
• int age;
• int year;
• };
• void main(){
• Student
s1={"Amir","Programming",19,2002},
s2;

• strcpy( s2.name,"Abbas Ali");
• s2.age=23;
• cin>>s2.year;
• cout<<s1.name<<" "<<s2.name<<endl;
• cout<<s1.course<<" "<<s2.course<<endl;
• cout<<s1.age<<" "<<s2.age<<endl;
• cout<<s1.year<<" "<<s2.year<<endl;
• getch();
• }

Structure
• Simple Variable of type
• Structure Pointer to Structure
• Arrays of Structures
• Function that returns a Structure
• Pass the Structure to functions

Structure (Arithmetic
Operation)
• Student stdnt1 , stdnt2 ;
• stdnt1 + stdnt2 ; //Wrong

Structure
• Student s1 , s2 ;
• s1 = s2 ;

#include<iostream>
#include<iomanip>
#include<cstring>
using namespace std;
struct Student{
char name [ 64 ];
char course [ 128 ];
int age;
int year;
};
int main(){
Student
s1={"Amir","Programming",19,2016},s2;
s2=s1;
cout<<s2.name<<endl<<s2.course<<endl;
cout<<s2.age<<endl<<s2.year<<endl;
}

Pointers to Structure
• Student *sPtr , s1 ;
• sPtr = &s1 ;
• *sPtr.name ; Wrong
• sPtr ->name ;
• Same as
• s1.name

#include<iostream>
#include<iomanip>
#include<cstring>
struct Student{
char name [ 64 ];
int age;
int year;
};
int main(){
Student
s1={"Amir","Programming",19,2016},*s2;
s2=&s1;
cout<<s2->name<<endl;
cout<<s2->course<<endl;
cout<<s2->age<<endl;
cout<<s2->year<<endl;

struct Student{
char name [ 64 ];
int age;
int year;
};
int main(){
Student *s1=new Student;
strcpy(s1->name,"Amir");
strcpy(s1->course,"Programming");
s1->age=19;
s1->year=2016;
cout<<s1->name<<endl;
cout<<s1->course<<endl;
cout<<s1->age<<endl;
cout<<s1->year<<endl;
}

Passing Structures to
Functions
Call by value
Call by Reference  X

• struct Student{
• char name[20];
• int rollno;
• };
• void init(Student&);
• void main(){
• Student s1;
• init(s1);
• cout<<s1.name<<" "<<s1.rollno;
• getch();
• }
• void init(Student &a){
• cout<<"Plz enter the name n";
• gets(a.name);
• cout<<"Plz enter the Roll No n";
• cin>>a.rollno;
• }

Arrays of Structure
• Student s [ 100 ] ;
• s [ 0 ].name ;
• s [ 1 ].name ;
• s [ 2 ].name ;
• . . .
• s [ 99 ].name ;

Example 3
• char firstName [ 30 ] ;
• char lastName [ 30 ] ;
• char course [ 15 ] ;
• char rollNo [ 10 ] ;
• int age ;
• float gpa ;
• } ;

programming fundamentals

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programming fundamentals