1. CSCE 206 Lab Structured Programming in C
Spring 2019
Lecture 8

2. Structs A struct is a user-defined data type
Used to group one or more variables into the same type
struct student {
char name[30];
int uin;
int phone_num;
int gpa; };
struct keyword
structure tag
Semicolon, do not forget to put it!

3. Structs: create a type
typedef struct { char name[30]; int uin; int phone_num; float gpa; } Student; Use uppercase in types! (not for variables)

4. Use a type struct
void main() { Student s1, s2; // declaration of two students with a Student type s1.gpa = 3.8; // set gpa value for the first student s2.gpa = 3.3; // set gpa for the second }

5. Use a type struct in functions
Student highestGPA(Student s1, Student s2) { if (s1.gpa > s2.gpa) return s1; else return s2; } void main() { Student s1, s2; // declaration of two students with a Student type s1.gpa = 3.8; // set gpa value for the first student s2.gpa = 3.3; // set gpa for the second Student best = highestGPA(s1, s2);

6. Use a type struct inside the struct
typedef struct Node { char name[30]; int uin; int phone_num; float gpa; struct Node *next; // you can only use the same type if declared in first line } Node;

7. Use a type struct with a pointer
void main() { Student s1; Student *pS1 = &s1; //pointer to student pS1->gpa = 3.8; // when using a pointer use -> instead of ‘.’ }

8. Arrays of structs
void main() { Student class[10]; class[0].gpa = 3.8; // modify GPA of first student of the class }

9. Structs that contain structs
typedef struct { float test1; float test2; } Grades; int uin; Grades grades; } Student; void main() { Student class[10]; class[0].grades.test1 = 83.2; // modify first grade of first student of the class }

10. Accessing structs
Student s; Student *ptr = &s; ptr->grades.test1 = 84.1; // through a pointer s.grades.test2 = 96.2; // through the student (*ptr).uin = ; // beware of the parenthesis!