Basic Data types in C Τι πρέπει να ξέρετε ήδη

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Oswald Benson
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1 int char float double Basic Data types in C Τι πρέπει να ξέρετε ήδη και αν όχι, χρειάζεται να το μάθετε

2 Variable declaration in C: Example: int x, y, z; type variables / instances Variable assignment: Example: x = 35; value

3 Boolean Has two values, true and false. In C we use integers as Booleans. 0 represents false. Any!=0 integer represents true. Έχετε δοκιμάσει x==-1;

4 Arrays (1D) array1d: 0 1 N - 1 All the elements are of the same type. An element: array1d[index] In C, the first element has index 0 (zero).

5 Strings : array of characters Example: char name[30]; Unlike other arrays, strings require an end-of-string character : \0 max length including \0

6 Multidimensional Arrays array2d: All the elements are of the same type. An element: array2d[row][column]

7 Example 1: #include <stdio.h> int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0;

8 #include <stdio.h> File inclusion header int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0;

9 #include <stdio.h> Function definition int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0;

10 #include <stdio.h> Function name int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0;

11 Function return type #include <stdio.h> int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0; Must be compatible with the function s return type

12 #include <stdio.h> int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0; Function parameter Parameter type

13 Example 1 #include <stdio.h> int leapyear(int year) if ((year % 4 == 0 && year % 100!= 0)) (year % 400 == 0) ) return 1; else return 0;

14 Example 2 int daytable[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; int dayofyear(int year, int month, int day) int i; int isleap = leapyear(year); for (i = 1; i < month; i++) day += daytable[isleap][i]; return day;

15 int daytable[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; Global variable int dayofyear(int year, int month, int day) int i; Local variable int isleap = leapyear(year); for (i = 1; i < month; i++) day += daytable[isleap][i]; return day;

16 int daytable[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; int dayofyear(int year, int month, int day) int i; int isleap = leapyear(year); for (i = 1; i < month; i++) day += daytable[isleap][i]; 2-dimensional array of int return day;

17 int daytable[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; int dayofyear(int year, int month, int day) int i; int isleap = leapyear(year); for (i = 1; i < month; i++) day += daytable[isleap][i]; return day;

18 Example 2 int daytable[2][13] = 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ; int dayofyear(int year, int month, int day) int i; int isleap = leapyear(year); for (i = 1; i < month; i++) day += daytable[isleap][i]; return day;

19 Example 2 (main) main() int year, month, day; printf( Enter year, month and day: ); scanf( %d %d %d, &year, &month, &day); day = dayofyear(year, month, day); printf( \nday of Year = %d\n, day);

20 main() int year, month, day; printf( Enter year, month and day: ); scanf( %d %d %d, &year, &month, &day); day = dayofyear(year, month, day); printf( \nday of Year = %d\n, day); Function call

21 Struct (δομή) Structure Name member1 (μέλος) member2 member3 member4 Members may have different types. structure.member1 structs are also known as records (εγγραφές) and members as fields (πεδία)

22 typedef Gives a new name to a type that has already been defined. E.g. typedef int Boolean; Saves typing struct SomeRec everywhere.

23 Example 3: #include <stdio.h> #define MAXNAME 80 struct StudentRec char name[maxname]; int mark; ; typedef struct StudentRec Student;

24 #include <stdio.h> #define MAXNAME 80 Macro substitution struct StudentRec char name[maxname]; int mark; ; typedef struct StudentRec Student;

25 #include <stdio.h> Structure declaration #define MAXNAME 80 struct StudentRec char name[maxname]; int mark; ; typedef struct StudentRec Student;

26 #include <stdio.h> #define MAXNAME 80 struct StudentRec char name[maxname]; int mark; ; Structure name / tag Members Don t forget this! typedef struct StudentRec Student;

27 #include <stdio.h> #define MAXNAME 80 struct StudentRec char name[maxname]; int mark; ; Data type New type name typedef struct StudentRec Student;

28 Student readstudent(void) Student next; scanf( %s %d, next.name, &next.mark); return next; /* next.name without & */ void printstudent(const Student student) printf( %s %d\n, student.name, student.mark);

$mark); return next; Package A member of a struct variable void printstudent(const Student student) printf( %s %d\n,$

29 Student readstudent(void) Student next; An instance of the struct scanf( %s %d, next.name, &next.mark); return next; Package A member of a struct variable void printstudent(const Student student) printf( %s %d\n, student.name, student.mark);

30 #define MAXCLASS 100 main() Student class[maxclass]; int n, i, best = 0; printf( Enter number of students: ); scanf( %d, &n); for (i = 0; i < n; i++) class[i] = readstudent(); if (class[best].mark < class[i].mark) best = i; printf( Best student is: ); printstudent(class[best]);

31 #define MAXCLASS 100 main() Student class[maxclass]; int n, i, best = 0; Array of instances of structs printf( Enter number of students: ); scanf( %d, &n); Assignment for (i = 0; i < n; i++) class[i] = readstudent(); if (class[best].mark < class[i].mark) best = i; Member of an array element printf( Best student is: ); printstudent(class[best]);

Variables Data types Variable I/O. C introduction. Variables. Variables 1 / 14

C introduction Variables Variables 1 / 14 Contents Variables Data types Variable I/O Variables 2 / 14 Usage Declaration: t y p e i d e n t i f i e r ; Assignment: i d e n t i f i e r = v a l u e ; Definition