3 Review of basic structured programming

1. 3 Review of basic structured programming M Taimoor Khan taimoorkhan@ciit-attock.edu.pk

2. Pointers • What are Pointers • They store addresses like variables store values • Why do we need them • Accessing array elements • Passing argument to functions when they need the original copy • Passing arrays and strings to functions • Creating data structures

3. variables #include<iostream.h> void main() { int a = 5; cout <<a <<endl; cout <<&a; }

4. Pointers Declaration #include<iostream.h> void main() { int a; int b, c, d; int *ptr1; int *ptr2, *ptr3, *ptr4; }

5. Accessing Pointers #include<iostream.h> void main() { int a = 6; int *ptr; ptr = &a; cout <<ptr<<endl; cout <<*ptr <<endl; }

6. Using Pointers #include<iostream.h> void main() { int a = 5; float b = 4.4; double c = 1.345; int *ptr1; ptr1 = &a; float *ptr2; ptr2 = &b; double *ptr3; ptr3 = &c; cout <<ptr1 <<“\t” <<*ptr1<<endl; cout <<ptr2<<“\t” <<*ptr2<<endl; cout <<ptr3<<“\t” <<*ptr3<<endl; }

7. Pointers and Arrays #include<iostream.h> void main() { intarr[] = {7, 4, 3, 5, 2}; for(inti=0; i<5; i++) cout <<arr[i] <<“\t”; cout<<endl; int *ptr; ptr = arr; for(inti=0; i<5; i++) cout <<ptr+i<<“\t”<<*(ptr+i)<<endl; }

8. Pointers and Arrays #include<iostream.h> void main() { intarr[] = {7, 4, 3, 5, 2}; for(inti=0; i<5; i++) cout <<arr[i] <<“\t”; cout<<endl; int *ptr; ptr = arr; for(inti=0; i<5; i++) cout <<*ptr++<<endl; }

9. Pointers to Functions #include<iostream.h> void halfValue(int *v2) { *v2 = *v2 /2; } void main() { int score = 7; int *ptr; ptr = &score; halfValue(ptr); cout<<ptr<<endl; cout <<*ptr<<endl; cout <<score<<endl; }

10. Array Pointers to Functions #include<iostream.h> Int MAX = 5; void add(int *arrPointer) { int sum = 0; for(inti=0; i<MAX; i++) sum += *arrPointer++; cout <<“Total: “<<sum; } void main() { intarr[MAX] = {4, 3, 6, 8, 1}; int *ptr; ptr = arr; add(ptr); }

11. Pointer to Constant String #include<iostream.h> void main() { char str = “This is a constant string”; char *ptr; ptr = str; cout<<str<<endl; cout <<ptr<<endl; cout<<*ptr<<endl; cout<<*ptr+1<<endl; cout <<*(ptr+1)<<endl; }

12. Pointers to Character Arrays #include<iostream.h> void main() { char str[] = {‘a’, ‘b’, ‘d’, ‘f’}; char *ptr; ptr = str; cout<<str<<endl; cout <<ptr<<endl; cout<<*ptr<<endl; cout<<*ptr+1<<endl; cout <<*(ptr+1)<<endl; }

13. Special Pointer Type #include<iostream.h> void main() { int a = 6; float b = 3.2; void *ptr; ptr = &a; cout <<ptr<<endl; ptr = &b; cout <<ptr<<endl; }