1 / 11

Engr 0012 (04-1) LecNotes 25-01

Engr 0012 (04-1) LecNotes 25-01. use defined constant to specify maximum number of elements in the array. type of values. meaningful name. maximum number of elements in [ ]. arrays do not need to be “full” - need to keep track of how much is actually used. Arrays - review.

daphne
Download Presentation

Engr 0012 (04-1) LecNotes 25-01

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Engr 0012 (04-1) LecNotes 25-01

  2. use defined constant to specify maximum number of elements in the array type of values meaningful name maximum number of elements in [ ] arrays do not need to be “full” - need to keep track of how much is actually used Arrays - review Declaring an array // preprocessor commands #define MAXARRAYSIZE 100 … main() {  // variable declaration double length[MAXARRAYSIZE], // array of lengths width[MAXARRAYSIZE]; // array of widths int actualsize, // actual amt in use i; // loop index … Engr 0012 (04-1) LecNotes 25-02

  3. &length[0] &length[MAXARRAYSIZE-1] … … &length[actualsize-1] declaration sets aside MAXARRAYSIZE memory locations capable of holding specified type of information compiler remembers only location (address of) first location &length[0] length do not need to use entire allocation of memory ==> need to keep track of actualsize Arrays Memory management Engr 0012 (04-1) LecNotes 25-03

  4. &length[0] &length[MAXARRAYSIZE-1] … … &length[actualsize-1] length[0] length[8] length[18] length[-2] length[260] Arrays Using arrays accessing values - name and index Engr 0012 (04-1) LecNotes 25-04

  5. N rows M columns Two dimensional arrays - tables/matrices 1.200 3.412 5.321 21.872 -16.322 -23.333 16.098 0.987 9.765 2.908 -0.888 312.099 222.987 16.999 87.434 -8.909 54.669 322.419 -435.666 -87.554 0.988 16.234 -76.287 12.359 Dimension: NxM (rows x columns) if N = M (i.e., dimension NxN) square matrix still require all values be of same type Engr 0012 (04-1) LecNotes 25-05

  6. use defined constants to declare dimensions if square matrix, only need one size #define MAX2D 10 specify rows and columns double length[MAX2D][MAX2D]; // table of lengths keep track of amount in use Two dimensional arrays - declaring // preprocessor commands #define MAXROW 10 #define MAXCOL 10 … main() {  // variable declaration double length[MAXROW][MAXCOL]; // table of lengths int actrows, // actual rows in use actcol, // actual col in use i,j,k; // loop indices … Engr 0012 (04-1) LecNotes 25-06

  7. length[1][2] value in 2nd row, 3rd column &length[6][4] address of value in 7th row, 5th column &length[0][0] length address of first element Two dimensional arrays - using Engr 0012 (04-1) LecNotes 25-07

  8. [ ] tells that the variable is an array need to send amount actually in use used to return number of values actually in use Arrays - function prototypes/parameter lists // preprocessor commands #define MAXARRAYSIZE 100 … main() {  // variable declaration double length[MAXARRAYSIZE], // array of lengths width[MAXARRAYSIZE]; // array of widths int actualsize, // actual amt in use i; // loop index … // function prototypes int getarray( double length[ ] ); double avearray( double length[ ], int actsize );   Engr 0012 (04-1) LecNotes 25-08

  9. name w/o [ ] Arrays - calling statements/parameter lists // preprocessor commands #define MAXARRAYSIZE 100 // function prototypes int getarray( double length[ ] ); double avearray( double length[ ], int actsize );   … main() {  // variable declaration double length[MAXARRAYSIZE], // array of lengths width[MAXARRAYSIZE]; // array of widths int actualsize, // actual amt in use i; // loop index // calling statement actualsize = getarray( length ); ave = avearray( length, actualsize )  ==> sending address of first element Engr 0012 (04-1) LecNotes 25-09

  10. need to send amount in use need to specify maximum number of columns 2D arrays - function prototypes/parameter lists // preprocessor commands #define MAX1D 100 #define MAX2D 100 … main() {  // variable declaration double oned[MAX1D]; // 1D array double twod[MAX2D][MAX2D]; // 2D array int onedact, // 1D array in use actrows, // actual amt in use i,j,k; // loop indices  … // function prototypes void fill( double onedarray[], int used1D, double twodarray[][MAX2D], int used2D );   Engr 0012 (04-1) LecNotes 25-10

  11. local array name w/o [] ==> sending address 2D arrays - calling statements/parameter lists // preprocessor commands #define MAX1D 100 #define MAX2D 100 … main() {  // variable declaration double oned[MAX1D]; // 1D array double twod[MAX2D][MAX2D]; // 2D array int onedact, // 1D array in use actrows, // actual amt in use i,j,k; // loop indices  … // function prototypes void fill( double onedarray[], int used1D, double twodarray[][MAX2D], int used2D );   // calling statement fill( oned, onedact, twod, actrows ); Engr 0012 (04-1) LecNotes 25-11

More Related