C Programming Language

Transcription

1 C Programming Language Structures Manar Mohaisen Office: F208 Department of EECE

2 Review of the Precedent Lecture Explained How to Handle Character Strings Department of Electrical, Electronics, and Communication Engineering Explained How to define a String in a Program Again, Explained the Difference bet. Pointer and Array Explained How to Input a String Explained How to Output a String

3 Class Objectives Introduce Structures Explain the Usage of Structures Introduce Nested Structures Introduce Unions and Enumerations Discussions

4 Introduction Variable Hold a single data element with a specific data type. Array A series of elements having the same data type. Structure Collection of variables having the same or different sizes and same or different data types.

5 Structures Book Department of Electrical, Electronics, and Communication Engineering /* book.c -- one-book inventory */ #include <stdio.h> #define MAXTITL 41 /* maximum length of title + 1 */ #define MAXAUTL 31 /* maximum length of author's name + 1 */ struct book{ /* structure template */ char title[maxtitl]; char author[maxautl]; float value; /* end of structure template */ void main(void) { struct book library; /* declare library as a book variable */ printf("please enter the book title.\n"); gets(library.title); /* access to the title portion */ printf("now enter the author.\n"); gets(library.author); printf("now enter the value.\n"); scanf("%f", &library.value); printf("%s by %s: $%.2f\n",library.title, library.author, library.value); printf("done.\n"); }

6 Structures contd. Structure Declaration struct book{ /* structure template */ char title[maxtitl]; char author[maxautl]; float value; /* end of structure template */ A structure made up of Two char arrays (strings) and one float variable. Another structure struct student{ /* structure template */ char name[40]; int id; float gpa; /* end of structure template */

7 Structures contd. Defining a Structure Variable sturct plays the same role that int or double does in simple declaration. struct student jack; struct student * elec;

8 Structures contd. Combined Structure Declaration and Variable Definition struct student{ char name[40]; int id; float gpa; } huey; /* follow declaration with variable name */

9 Structures contd. Initializing a Structure Structure Declaration struct student{ char name[40]; int id; float gpa; Initialization struct student huey{ Huey Morgan Freeman, 2006, 4.5 struct student huey{.name = Huey Morgan Freeman,.id = 2006,.gpa = 4.5 struct student huey{.id = 2006,.name = Huey Morgan Freeman,.gpa = 4.5

10 Structures contd. Array of Structures struct student{ char name[40]; int id; float gpa; } elec[3]; An array of structures.

11 Structures contd. Be careful! struct student{ char name[40]; int id; float gpa; } elec[3]; elec.name = Huey ; \\ Wrong elec[1].name = Huey ; \\ Right elec[1].name[3] = e ; \\ Right

12 Structures contd. Nested Structures struct student{ char name[40]; int id; float gpa; struct student{ struct student primary; int gradyear; char company[50]; } huey; huey.primary.name = Huey Morgan Freeman ; huey.primary.id = 15; huey.primary.gpa = 4.35; huey.gradyear = 2015; huey.company = LG Electronics ;

13 Nested Structures contd. Nested Structures contd. struct student{ char name[40]; int id; float gpa; Department of Electrical, Electronics, and Communication Engineering struct gradstudent{ struct student primary; int gradyear; char company[50]; } huey; huey = { { Huey Morgan Freeman, 15, 4.35}, 2010, LG Electronics

14 Nested Structures contd. Example Department of Electrical, Electronics, and Communication Engineering # include <stdio.h> struct student { char name[40]; int Studentid; double gpa; /* grade point average */ struct gradstudent { struct student primary; char workplace[40]; int gradyear; void main(){ struct gradstudent huey = { {"Huey Freeman", , 4.5}, "LG Electronics", 2010 printf("mr. %s\n", huey.primary.name); printf(" Student ID: %d\n", huey.primary.studentid); printf(" GPA : %f\n", huey.primary.gpa); printf(" Grad. year: %d\n", huey.gradyear); printf(" Company : %s\n", huey.workplace); }

15 Pointers to Structures Example Department of Electrical, Electronics, and Communication Engineering # include <stdio.h> Output struct student { 0012FF FF80 char name[20]; int Studentid; double gpa; // grade point average // void main() { struct student huey = { "Huey Morgan Freeman", 20067, 4.5 } struct student * ptrs; ptrs = &huey; printf("%p \t %p\n", (ptrs), ptrs+1);

16 Pointers to Structures contd. Example (Array of Structures) Department of Electrical, Electronics, and Communication Engineering # include <stdio.h> Output struct student { Huey Morgan Freeman char name[20]; Reilly Bob Flowers int Studentid; double gpa; // grade point average // void main() { struct student Huey[2] = { {"Huey Morgan Freeman", 20067, 4.5}, {"Reilly Bob Flowers, 20052, 4.2} } struct student * ptrs; ptrs = &Huey[0]; for(ii = 0; ii < NUM; ii++) printf("%20s \t %d \t %.2f \n", (ptrs+ii)->name, (ptrs+ii)->studentid, (ptrs+ii)->gpa);

17 Pointers to Structures contd. Example Department of Electrical, Electronics, and Communication Engineering struct student{ char name[40]; int id; double gpa; struct student huey[2]; struct student * ptr; ptr = &huey; // same as ptr = &huey[0]; huey[0].id = ; (ptr + 1).id = ; // WRONG (ptr + 1)->id = ; // Correct (*(ptr + 1)).id = ;

18 Passing Structure Members Example #include <stdio.h> #define FUNDLEN 50 struct funds{ char bank[fundlen]; double bankfund; char save[fundlen]; double savefund; double sum(double, double); void main(void) { struct funds stan = { } "Garlic-Melon Bank", , "Lucky's Savings and Loan", Department of Electrical, Electronics, and Communication Engineering double sum(double x, double y) { return(x + y); } printf("stan has a total of $%.2f.\n", sum(stan.bankfund, stan.savefund) );

19 Using the Structure Address Example #include <stdio.h> #define FUNDLEN 50 struct funds { char bank[fundlen]; double bankfund; char save[fundlen]; double savefund; Department of Electrical, Electronics, and Communication Engineering double sum(const struct funds * money) { return(money->bankfund + money->savefund); } double sum(const struct funds *); /* argument is a pointer */ void main(void) { struct funds stan = { "Garlic-Melon Bank", , "Lucky's Savings and Loan", printf("stan has a total of $%.2f.\n", sum(&stan)); }

20 Passing a Structure as an Argument Example #include <stdio.h> #define FUNDLEN 50 struct funds { char bank[fundlen]; double bankfund; char save[fundlen]; double savefund; double sum(struct funds woori) { return(woori.bankfund + woori.savefund); } double sum(struct funds moolah); /* argument is a structure */ void main() { struct funds stan = { "Garlic-Melon Bank", , "Lucky's Savings and Loan", printf("stan has a total of $%.2f.\n", sum(stan)); }

21 Enumeration Example A set of named integer set The value of the first element is 0. #include <stdio.h> #define FUNDLEN 50 #include <stdio.h> enum decicion {NO, YES void main() { enum decision onoff = 1; } if(onoff == NO) printf("i like C language, but not that much :) \n"); else if(onoff == 1) printf("i love C language and admire Dennis Ritchie. \n");

22 Other Types Unions Same as the structure with the exception that only one of its elements can be given a value at a time.

23 Go beyond simple programs ^^ An example (dealing with complex numbers) Department of Electrical, Electronics, and Communication Engineering # include <stdio.h> # include <stdio.h> # include <stdlib.h> # include <time.h> # define N 5 struct complex { double real; double imag; double Cpower(const struct complex *, int n); void Crandom(struct complex *, int n); void main(){ struct complex * Carray; double Cpow = 0.; Carray = (struct complex *)calloc(n, sizeof(struct complex)); Crandom(Carray, N); Cpow = Cpower(Carray, N); } printf("total ower of the vector = %lf\n", Cpow); free(carray);

24 Summary & Discussion Introduced Structures Department of Electrical, Electronics, and Communication Engineering Explained the Usage of Structures Introduced Nested Structures Introduced Unions and Enumerations