CSE240 Lecture 10

Introduction to Programming Languages
Arrays and Pointers
(202009)

Transcript

1. jgs CSE 240 Introduction to Programming Languages Lecture 10: Arrays and Pointers Dr. Javier Gonzalez-Sanchez javiergs@asu.edu javiergs.engineering.asu.edu | javiergs.com PERALTA 230U Office Hours: By appointment
2. jgs Previously …
3. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 3 jgs Arrays are Pointers § An array is a pointer to a set of consecutive elements a[0] is the same that *(a+0) a[1] is the same that *(a+1) a[2] is the same that *(a+2) a[3] is the same that *(a+3) etc. int a [6]; 0x48 a 0x44 0x48
4. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 4 jgs Arrays are Pointers #include <stdio.h> void main() { int i = 0; char a[ ] = "Hello CSE 240"; printf("\n message: %s\n ", a); while (a[i] != '\0') { a[i] = *(a + i)+1; i++;} printf("\n message after encryption: %s\n ", a); char *q; q = a; while (*q != '\0') { *q = *q-1; q++;} printf("\n message after decryption: %s\n ", a); } a[i] = *(a + i)+ 1 a[i] = a[i]+ 1 *(a+i) = a[i]+ 1 *(a+i) = *(a+i)+ 1
5. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 5 jgs Arrays are Pointers #include <stdio.h> void main() { int i = 0; char a[ ] = "Hello CSE 240"; printf("\n message: %s\n ", a); while (a[i] != '\0') { a[i] = *(a + i)+1; i++;} printf("\n message after encryption: %s\n ", a); char *q; q = a; while (*q != '\0') { *q = *q-1; q++;} printf("\n message after decryption: %s\n ", a); } 0x48 a 0x44 H 0x48 e l l ... 0x48 q 0x94
6. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 6 jgs Arrays are Pointers #include <stdio.h> void main() { int i = 0; char a[ ] = "Hello CSE 240"; printf("\n message: %s\n ", a); while (a[i] != '\0') { a[i] = *(a + i)+1; i++;} printf("\n message after encryption: %s\n ", a); char *q; q = a; while (*q != '\0') { *q = *q-1; q++;} printf("\n message after decryption: %s\n ", a); }
7. jgs Arrays, Strings, and Pointers
8. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 8 jgs Test Yourselves
9. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 9 jgs Test Yourselves
10. jgs Test yourselves
11. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 11 jgs 1
12. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 12 jgs 2
13. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 13 jgs 3
14. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 14 jgs 4
15. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 15 jgs 5
16. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 16 jgs Let’s Work
17. jgs What about 2D arrays?
18. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 18 jgs 2D Array
19. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 19 jgs Questions
20. jgs CSE 240 Introduction to Programming Languages Javier Gonzalez-Sanchez, Ph.D. javiergs@asu.edu Fall 2021 Copyright. These slides can only be used as study material for the class CSE240 at Arizona State University. They cannot be distributed or used for another purpose.