Structs as Function Arguments and Results

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Structs as Function Arguments and Results

Arrays– Pass by referance

Struts– the same way as the basic types in C - char, int, float

- passed as arguments

- returned as results

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typedef struct Person{

int age;

char gnd;

float weight;

} PERSON;

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the use of the members of a struct.

int adjustAge( int oldAge ){

if ( oldAge < 39 ) return( ++oldAge );

else return( oldAge );

/*return (oldAge<39) ? ++oldage : oldage;*/

}

void main(){

PERSON Jim;

:

Jim.age = adjustAge( Jim.age );

:

}

3


typedef struct Book{

int edition;

int pages;

double weight;

char type;

int WC; /*weight classification 1 heavy, 0 is not */

} BOOK;

Write a function tack an argument double to test the weight of a book and return 1 if the weight greater than 2 and 0 otherwise. The value to be assign to WC member.

4


int weightC(double w){

if(w > 2) return 1;

else return 0;

}

void main(){

BOOK myBok;

:

myBoK.wc = weightC(myBok.weight);

:

}

5

int weightC(double w){

return (w > 2)? 1 : 0;

}


ASS

Consider the student struct: add a new member name it GL /*Grades Later*/

Write a function tack a double to test the average of the student and return a later match the average to be assign to the new member

Test the function

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The whole of a struct is returned by a function

PERSON get_details() {

PERSON temp;

printf("Please enter Age, Gender and Weight (Kg): ");

scanf("%d %c%f", &temp.age, &temp.gnd, &temp.weight );

return temp;

}

void main(){

PERSON Jim, Mary, Sid;

:

Jim = get_details();

:

}

7


Write a function allow the user to input the details of a BOOK and return it back


int edition;

int pages;

double weight;

char type;

} BOOK;

8


BOOK GetBook(){

BOOK tmp;

printf(“\nEnter the BOOK information:”);

printf(“ [edition, pages, weight, and type]”);

scanf(“%d%d%f%c”, &tmp.edition, &tmp.pages. &tmp.weight. &tmp.type);

retrun tmp;

}

void main(){

BOOK myBook;

:

myBook = GetBook();

:

}

9


ASS

Write a function allow the user to input the details of a STUDENTand return it back

Test the function

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Passing a struct as a function argument

void show_details( PERSON who ){

printf( "Person's age was: %d\n", who.age );

printf( " Gender was: %c\n", who.gnd );

/* Kg -> lb */

who.weight = who.weight * 2.2;

printf( " weight (lb) was: %5.1f\n", who.weight );

}

void main(){

PERSON Jim, Mary, Sid;

:

Jim = get_details();

:

show_details(Jim);

}

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Write a function tack a BOOK and print the content out

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void PrintBook( const BOOK b){

printf(“The BOOK information:\n”);

printf(“\n\tedition: %d\n\tpages: %d”, b.edition, b.pages);

printf(“\n\tweight: %f \n\ttype: %c”, b.weight, b.type);

}

void main(){

BOOK myBook = {2, 120, 2.5, ‘A’};

:

PrintBook(myBook);

:

}

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ASS

Write a function tack a STUDENT and print the content out

Test the function

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Arrays of structs

to store the same package of information for a number of different entities

typedef struct Person{

int age;

char gnd;

float weight;

} PERSON;

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Arrays of structs

PERSON employee[12];

We have an array of 12 elements each of which is a structure with 3 members. We can access any member of any element,

employee[9].age = 45;

Also we can treat each element as a whole structshow_details(employee[5]);

employee[3] = get_details();

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Consider the following struct BOOK, Create an array of three BOOK s


int edition;

double weight;

char type;

} BOOK;

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BOOK academic[3];

BOOK academic[3] = {

{1,2.5,’a’},

{2,3.5,’n’},

{2,1.5,’a’}

};

Read in the information of the second

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academic[1] = GetBook();

Printout the information of the first

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PrintBook(academic[0]);

Printout the content of the array

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int i;

for(i=0; i<3; i++)

PrintBook(academic[i]);

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ASS

1. Create an array of four STUDNTs with initial values

2. – Create another array of five STUDNTs

– Read in the information of the whole student

– Printout the content

– Assign the second the information of the second of the array created at 1

– Printout the information of the second

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Structs Containing Arrays

typedef struct{

int age;

char gnd;

float weight;

char name[20];

} HUMAN;

HUMAN ahm = { 45, ‘M’, 95.1, “Ahmad Ali”};HUMAN ahm = { 45, ‘M’, 95.1, {‘A’, ‘h’, ‘m’, ‘a’, ‘d’, ‘ ‘, ‘A’, ‘l’, ‘i’, ‘\0’}};

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char initial = ahm.name[0];

putchar(initial);

Printout the 3rd char of ahm’s name

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char third = ahm.name[2];

printf(“%c”, third); /*putchar(third)*/

allow the user to input the 6th char of ahm’s name

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scanf(“%c”, &ahm.name[5]);

print the name char by char

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int i;

for(i=0; i<20; i++)

putchar(ahm.name[i]);

i=0;

while( ahm.name[i] != ‘\0’)

putchar(ahm.name[i++]);

Print out the name at once

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printf(“%s\n”, ahm.name);

puts(ahm.name);

allow the user to input the ahm’s name

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scanf(“%s”, ahm.name);

gets(ahm.name);

Which is better?

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int edition;

double weight;

char type;

} BOOK;

Rewrite the BOOK with a new member title

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int edition;

double weight;

char type;

char title[30];

} BOOK;

Create a variable of book with initial values

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BOOK myBook = {1,2.5,’a’, “C programming” }

change the title to “c how to program”

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gets(myBook.title);

scanf(“%s”, myBook.title);

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ASS

Create a Time struct with classification member (“PM”, “AM”)

Write a function to print out the content of the Time

Create a STUDENT struct with a name member up to 30 char

Write two functions to read the information of a student and the second to print out the information.

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HUMAN client[2] = {

35, ‘M’, 95.1, “Ahmad Ali”,

25, ‘F’, 50.9, "Salma Zakarea”

};

printf( "%s\n", client[1].name );

printf( "%c\n", client[1].name[0] );

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HUMAN client[2] = {

35, ‘M’, 95.1, “Ahmad Ali”,

25, ‘F’, 50.9, "Salma Zakarea”

};

HUMAN temp;

Assign the values of first client to temptypedef struct{

int age;

char gnd;

float weight;

char name[20];

} HUMAN;

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temp = client[0];

temp.age = client[0].age;

temp.gnd = client[0].gnd;

Temp.weight = client[0].weight;

strcpy(temp.name, client[0].name);

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Structs as Function Arguments and Results

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