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Structures of Functions

Structures of Functions. Group 3 - Steven Lyons - Jonathan Velez - Christopher Wallace Graciela Alonso Alert Kusaku. Today we’ll be discussing…. Passing a structure to a function without and with a pointer Summary of the lessons learned. 2. Program Diagram. CREATE STRUCTURE DATA.

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Structures of Functions

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  1. Structures of Functions • Group 3- Steven Lyons • - Jonathan Velez • - Christopher Wallace • Graciela Alonso • Alert Kusaku

  2. Today we’ll be discussing… • Passing a structure to a function without and with a pointer • Summary of the lessons learned 2

  3. Program Diagram CREATE STRUCTURE DATA DECLARE A FUNCTION PROTOTYPE SPECIFY STRUCTURE DATA VARIABLE“REC” RETRIEVE USER INPUT PURPOSE OF THE PROGRAM: THIS PROGRAM ALLOWS THE USER TO INPUT INFORMATION REGARDING A DONER’S NAME AND THE AMOUNT DONATED INTO MEMORY. IT ALSO HAS THE CAPABILITY OF PRINTING OUT THE INFORMATION. CALL THE FUNCTION PRINT OUT RESULTS

  4. The Code • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; • }; • /* The function prototype. The function has no return value, */ • /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data x); • int main(void) • { • struct data rec; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec.fname, rec.lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec.amount); • /* Call the display function. */ • print_rec( rec ); • return 0; • } • void print_rec(struct data x) • { • printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, • x.amount); • }

  5. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } Headers • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */

  6. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } Defining a Structure • struct data{ • float amount; • char fname[30]; • char lname[30]; • };Semicolon needed to end structure data

  7. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } Function Prototype • void print_rec(struct data x);

  8. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } Main Function • int main(void) • { • struct data rec; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec.fname, rec.lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec.amount); • /* Call the display function. */ • print_rec( rec ); • return 0; • }

  9. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } PRINTF/ SCANF • int main(void) • { • struct data rec; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", &rec.fname, &rec.lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec.amount); • /* Call the display function. */ • print_rec( rec ); • return 0; • }

  10. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } CALLING THE FUNCTION • int main(void) • { • struct data rec; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec.fname, rec.lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec.amount); • /* Call the display function. */ • print_rec( rec ); • return 0; • }

  11. /* Demonstrates passing a structure to a function. */ #include <stdio.h> /* Declare and define a structure to hold the data. */ struct data{ float amount; char fname[30]; char lname[30]; }; /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ void print_rec(struct data x); int main(void) { struct data rec; /* Input the data from the keyboard. */ printf("Enter the donor's first and last names,\n"); printf("separated by a space: "); scanf("%s %s", rec.fname, rec.lname); printf("\nEnter the donation amount: "); scanf("%f", &rec.amount); /* Call the display function. */ print_rec( rec ); return 0; } void print_rec(struct data x) { printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, x.amount); } Print_rec Function Definition • void print_rec(struct data x) • { • printf("\nDonor %s %s gave $%.2f.", x.fname, x.lname, • x.amount); • }

  12. The Code Using a *Pointer • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  13. Defining a Structure1. struct data{ float amount; char fname[30]; char lname[30]; }; • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  14. Function Prototype10. void print_rec(struct data* x); • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(structdata* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  15. Main Function11.int main(void)12. { data *rec = new data; 13./* Input the data from the keyboard. */ 14. printf("Enter the donor's first and last names,\n"); 15. printf("separated by a space: "); 16. scanf("%s %s", rec->fname,rec->lname); 17 printf("\nEnter the donation amount: "); 18. scanf("%f", &rec->amount); 19. /* Call the display function. */ 20. print_rec( rec ); return 0; } • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  16. Print_rec Function20. print_rec( rec ); • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  17. Print_rec Function *Defined21.void print_rec(struct data * x) 22. { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); } • /* Demonstrates passing a structure to a function. */ • #include <stdio.h> • /* Declare and define a structure to hold the data. */ • struct data{ • float amount; • char fname[30]; • char lname[30]; }; • /* The function prototype. The function has no return value, */ /* and it takes a structure of type data as its one argument. */ • void print_rec(struct data* x); • int main(void) • { data *rec = new data; • /* Input the data from the keyboard. */ • printf("Enter the donor's first and last names,\n"); • printf("separated by a space: "); • scanf("%s %s", rec->fname, rec->lname); • printf("\nEnter the donation amount: "); • scanf("%f", &rec->amount); • /* Call the display function. */ • print_rec( rec ); return 0; } • void print_rec(struct data * x) • { printf("\nDonor %s %s gave $%.2f.", x->fname, x->lname, x->amount); }

  18. External Example: • Program Diagram • Code • Code using pointers • Output http://publications.gbdirect.co.uk/c_book/chapter6/structures.html

  19. Program Diagram SPECIFY STRUCTURE ARRAY “AR” RETRIEVE USER INPUT CREATE STRUCTURE DATA DECLARE A FUNCTION PROTOTYPE CALL THE FUNCTION INFUN PURPOSE OF THE PROGRAM: THIS PROGRAM ALLOWS THE USER TO INPUT LETTERS, ASSIGNS IT A VALUE FOR FONT TYPE AND SIZE. IT ALSO PRINTS OUT THE LETTERS AND THEIR PROPERTIES IN ALPHABETICAL ORDER. MAKE WP_CHAR STRUCTURES PRINT OUT RESULTS PUT STRUCTURES IN ORDER

  20. #include <stdio.h> • #include <stdlib.h> • #define ARSIZE 10 • struct wp_char{ • char wp_cval; • short wp_font; • short wp_psize; • }ar[ARSIZE]; • /* • * type of the input function - • * could equally have been declared above; • * it returns a structure and takes no arguments. • */ • struct wp_charinfun(void); • main(){ • inticount, lo_indx, hi_indx; • for(icount = 0; icount < ARSIZE; icount++){ • ar[icount] = infun(); • if(ar[icount].wp_cval == '\n'){ • /* • * Leave the loop. • * not incrementing icount means that the • * '\n' is ignored in the sort • */ • break; • } • } • /* now a simple exchange sort */ • for(lo_indx = 0; lo_indx <= icount-2; lo_indx++) • for(hi_indx = lo_indx+1; hi_indx <= icount-1; hi_indx++){ • if(ar[lo_indx].wp_cval > ar[hi_indx].wp_cval){ • /* • * Swap the two structures. • */ • struct wp_charwp_tmp = ar[lo_indx]; • ar[lo_indx] = ar[hi_indx]; • ar[hi_indx] = wp_tmp; • } • } • /* now print */ • for(lo_indx = 0; lo_indx < icount; lo_indx++){ • printf("%c %d %d\n", ar[lo_indx].wp_cval, • ar[lo_indx].wp_font, • ar[lo_indx].wp_psize); • } • exit(EXIT_SUCCESS); • } • struct wp_char • infun(void){ • struct wp_charwp_char; • wp_char.wp_cval = getchar(); • wp_char.wp_font = 2; • wp_char.wp_psize = 10; • return(wp_char); • } The Code • The Header • Structure • Function Prototype • Main Function • Function Definition

  21. The Headers • Includes the stdio library • Includes the stdlib library • Defines ARSIZE as 10 • #include <stdio.h> • #include <stdlib.h> • #define ARSIZE 10

  22. Structure • Structure definition • wp_cval • wp_font • wp_psize • Array • comment • struct wp_char{ • char wp_cval; • short wp_font; • short wp_psize; • }ar[ARSIZE]; • /* • * type of the input function - • * could equally have been declared above; • * it returns a structure and takes no arguments. • */

  23. Function Prototype • Function infun: • Takes in no variables • Returns a wp_char structure • struct wp_charinfun(void);

  24. Main Function • Opening of main • Declare variables • for loop to run up to 10 times (ARSIZE) • The structures returned from the infun function go into ar array. • If the structure is a new line character, exit loop. • main(){ • inticount, lo_indx, hi_indx; • for(icount = 0; icount < ARSIZE; icount++){ • ar[icount] = infun(); • if(ar[icount].wp_cval == '\n'){ • /* • * Leave the loop. • * not incrementing icount means that the • * '\n' is ignored in the sort • */ • break; • } • }

  25. /* now a simple exchange sort */ • for(lo_indx = 0; lo_indx <= icount-2; lo_indx++) • for(hi_indx = lo_indx+1; hi_indx <= icount-1; hi_indx++){ • if(ar[lo_indx].wp_cval > ar[hi_indx].wp_cval){ • /* • * Swap the two structures. • */ • struct wp_charwp_tmp = ar[lo_indx]; • ar[lo_indx] = ar[hi_indx]; • ar[hi_indx] = wp_tmp; • } • } • /* now print */ • for(lo_indx = 0; lo_indx < icount; lo_indx++){ • printf("%c %d %d\n", ar[lo_indx].wp_cval, • ar[lo_indx].wp_font, • ar[lo_indx].wp_psize); • } • exit(EXIT_SUCCESS); • } • for loop puts structures in alphabetical order. • If current character value is greater, switch with lower structure. • for loop prints out values of structures in the structure array.

  26. Function • Header of function • Makes wp_char structure wp_char. • wp_cval get’s value of user’s input (one character) • wp_font get’s value of 2 • wp_psize get’s value of 10 • Returns wp_char • struct wp_char • infun(void){ • struct wp_charwp_char; • wp_char.wp_cval = getchar(); • wp_char.wp_font = 2; • wp_char.wp_psize = 10; • return(wp_char); • }

  27. #include <stdio.h> • #include <stdlib.h> • #define ARSIZE 10 • struct wp_char{ • char wp_cval; • short wp_font; • short wp_psize; • }ar[ARSIZE]; • void infun(struct wp_char *); • main(){ • struct wp_charwp_tmp, *lo_indx, *hi_indx, *in_p; • for(in_p = ar; in_p < &ar[ARSIZE]; in_p++){ • infun(in_p); • if(in_p->wp_cval == '\n'){ • /* • * Leave the loop. • * not incrementing in_p means that the • * '\n' is ignored in the sort • */ • break; • } • } • /* • * Now a simple exchange sort. • * We must be careful to avoid the danger of pointer underflow, • * so check that there are at least two entries to sort. • */ • if(in_p-ar > 1) for(lo_indx = ar; lo_indx <= in_p-2; lo_indx++){ • for(hi_indx = lo_indx+1; hi_indx <= in_p-1; hi_indx++){ • if(lo_indx->wp_cval > hi_indx->wp_cval){ • /* • * Swap the structures. • */ • struct wp_charwp_tmp = *lo_indx; • *lo_indx = *hi_indx; • *hi_indx = wp_tmp; • } • } • } • /* now print */ • for(lo_indx = ar; lo_indx < in_p; lo_indx++){ • printf("%c %d %d\n", lo_indx->wp_cval, • lo_indx->wp_font, • lo_indx->wp_psize); • } • exit(EXIT_SUCCESS); • } • void • infun( struct wp_char *inp){ • inp->wp_cval = getchar(); • inp->wp_font = 2; • inp->wp_psize = 10; • return; • } The Code using Pointers • The Header • Structure • Function Prototype • Main Function • Function Definition

  28. The Headers (The same as other) • Includes the stdio library • Includes the stdlib library • Defines ARSIZE as 10 • #include <stdio.h> • #include <stdlib.h> • #define ARSIZE 10

  29. Structure (The same as other) • Structure definition • wp_cval • wp_font • wp_psize • Array • comment • struct wp_char{ • char wp_cval; • short wp_font; • short wp_psize; • }ar[ARSIZE];

  30. Function Prototype • Function infun: • Uses pointer to wp_char structure • Returns nothing • void infun(struct wp_char *);

  31. Main Function • main(){ • struct wp_charwp_tmp, *lo_indx, *hi_indx, *in_p; • for(in_p = ar; in_p < &ar[ARSIZE]; in_p++){ • infun(in_p); • if(in_p->wp_cval == '\n'){ • /* • * Leave the loop. • * not incrementing in_p means that the • * '\n' is ignored in the sort • */ • break; • } • } • Opening of main • Declare variables • for loop to run up to 10 times (ARSIZE) • The infun function uses the in_p pointer, which points to a wp_char array. • If the structure is a new line character, exit loop.

  32. if(in_p-ar > 1) for(lo_indx = ar; lo_indx <= in_p-2; lo_indx++){ • for(hi_indx = lo_indx+1; hi_indx <= in_p-1; hi_indx++){ • if(lo_indx->wp_cval > hi_indx->wp_cval){ • /* • * Swap the structures. • */ • struct wp_charwp_tmp = *lo_indx; • *lo_indx = *hi_indx; • *hi_indx = wp_tmp; • } • } • } • Checks that there is more than one structure. If yes, does for loop to put in alphabetical order. • If current character value is greater, switch with lower structure.

  33. Using a for loop prints out all structures in alphabetical order. • Successful exit. • /* now print */ • for(lo_indx = ar; lo_indx < in_p; lo_indx++){ • printf("%c %d %d\n", lo_indx->wp_cval, • lo_indx->wp_font, • lo_indx->wp_psize); • } • exit(EXIT_SUCCESS); • }

  34. Function • Header of function • Takes wp_char structure pointer inp. • wp_cval get’s value of user’s input (one character) • wp_font get’s value of 2 • wp_psize get’s value of 10 • Returns to main. • void • infun( struct wp_char *inp){ • inp->wp_cval = getchar(); • inp->wp_font = 2; • inp->wp_psize = 10; • return; • }

  35. Lessons Learned • Structure values can be easily passed over with a "=" operator • That there can be arrays of structures • How to use structures • Passing structures to functions • Using the dot operator • Using the arrow operator

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