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
   

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2. jgs
   Previously …
   

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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
   

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4. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 4
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   Arrays are Pointers
   #include
   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
   

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5. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 5
   jgs
   Arrays are Pointers
   #include
   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
   

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6. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 6
   jgs
   Arrays are Pointers
   #include
   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);
   }
   

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7. jgs
   Arrays, Strings, and Pointers
   

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8. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 8
   jgs
   Test Yourselves
   

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9. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 9
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   Test Yourselves
   

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10. jgs
    Test yourselves
    

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11. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 11
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    1
    

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12. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 12
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    2
    

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13. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 13
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    3
    

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14. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 14
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    4
    

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15. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 15
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    5
    

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16. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 16
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    Let’s Work
    

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17. jgs
    What about 2D arrays?
    

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18. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 18
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    2D Array
    

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19. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 19
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    Questions
    

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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.
    

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