1. Thursday, January 18, 2007 The question of whether computers can think is just like the question of whether submarines can swim. -Edsger W. Dijkstra (1930 – 2002)

2. Self Test : String tokenizing: l Skip multiple spaces between words.

3. Function to swap two numbers.

4. void swap(int* sa, int *sb); //prototype int main() { int a=3; int b=5; cout<<a<<" "<<b<<endl; swap(&a, &b); cout<<a<<" "<<b<<endl; return 0; } void swap(int* sa, int *sb){ int temp=*sa; *sa=*sb; *sb=temp; }

5. There are three ways in C++ to pass arguments to a function: §Call by value §Call by reference with pointer arguments §Call by reference with reference arguments Calling Functions

6. void f(int *j); int main() { int i=10; int *p; p = &i; // p now points to i f(p); cout << i; // i is now ? return 0; } void f(int *j) { *j = 100; //pointee of j is assigned 100 } Call Functions with pointers

7. void f(int *j); int main() { int i=10; f(&i); cout << i; return 0; } void f(int *j) { *j = 100; //pointee of j is assigned 100 } Call Functions with pointers

8. int cubeByValue(int n); // prototype main() { int number = 5; cout <<"The original value of number is " << number << endl; number = cubeByValue(number); cout << "The new value of number is " << number << endl; return 0; } int cubeByValue(int n) { return n * n * n; //cube local variable n } Functions

9. void cubeByReference(int *nPtr); // prototype main() { int number = 5; cout << "The original value of number is " << number << endl; cubeByReference(&number); cout << "The new value of number is " << number << endl; return 0; } void cubeByReference(int *nPtr) {// cube number in main *nPtr = *nPtr * *nPtr * *nPtr; } Calling Functions with Pointers

10. void swap(int *pa, int *pb);//prototype int main() { int a=3; int b=5; cout<<a<<" "<<b<<endl; swap(&a, &b); cout<<a<<" "<<b<<endl; return 0; } void swap(int *pa, int *pb){ int *temp; temp=pa; pa=pb; pb=temp; } WHAT IS WRONG WITH THE FOLLOWING?

11. void convert(char *sPtr); main() { char string[] = "characters and $32.98"; cout << "The string before conversion is: " << string << endl; convert(string); cout << "The string after conversion is: " << string << endl; return 0; } void convert(char *sPtr) { while (*sPtr != '\0') { if (*sPtr >= 'a' && *sPtr <= 'z') *sPtr = toupper(*sPtr); ++sPtr; // increment sPtr to point to the next character } Calling Functions with Pointers

12. The new operator int *x_ptr; x_ptr=new int; OR int *x_ptr=new int; //heap Dynamic allocation

13. int *x_ptr=new int; *x_ptr=73; int *x2_ptr=new int; *x2_ptr=65; Dynamic allocation

14. What is wrong here? int *x_ptr=new int; *x_ptr=73; int *x2_ptr; *x2_ptr=65; Dynamic allocation

15. int *x_ptr=new int; *x_ptr=73; int *x2_ptr; x2_ptr=x_ptr; *x2_ptr=65; Dynamic allocation

16. movie… Dynamic allocation

17. //What is wrong here? int *x_ptr=new int; *x_ptr=73; int *x2_ptr=new int; x2_ptr=x_ptr; *x2_ptr=65; Dynamic allocation

18. //What is wrong here? int *x_ptr=new int; *x_ptr=73; int *x2_ptr=new int; x2_ptr=x_ptr; *x2_ptr=65; //memory leak Dynamic allocation

19. int *my_ptr=new int; *my_ptr=76; cout<<*my_ptr; delete my_ptr; Dynamic allocation

20. int *my_ptr=new int; *my_ptr=76; cout<<*my_ptr; delete my_ptr; int *my_ptr=new int(76); cout<<*my_ptr; delete my_ptr; Dynamic allocation

21. Another example… Dynamic allocation

22. double *p=new double[10]; /*10 element array*/ int i, size=10; for (i=0; i<size; i++){ p[i]=2.0*i; } for (i=0; i<size; i++){ cout<<p[i]<<endl; } delete []p; Dynamic allocation