Passing Structure Variable to a function

C Passing Structure Variable to a function

Similar like ordinary data type variables, a structure variable can also be passed to a function.

Either pass a individual structure elements or the entire structure at one go.

We can also pass the addresses of structure elements or address of a structure variable.

In programming, we usally deal with collection of ints, chars and floats rather than isolated entities.

Example an entity book is a collection of things like a title, an author, total pages, date of publication and price etc..

Structure is user defined data type which combines dissimilar data types into an entity.

C program to pass structure variable to a function

This c program is the example to pass entire structure variable to a function.

structure variable b1 is passed to function show where displayed the entire structure variable.

#include<stdio.h>                                                          
                                                                                
struct book                                                                     
{                                                                               
  int id;                                                                       
  char *title;                                                                  
  char *author;                                                                 
  float price;                                                                  
};                                                                              
                                                                                
void show(struct book b1)                                                       
{                                                                               
  printf("Inside show function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);          
}                                                                               
void main()                                                                     
{                                                                               
  struct book  b1 = {1, "book1", "author1", 20.5};                              
  show(b1);                                                                     
                                                                                
  printf("Inside main function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);          
}   

Output:

$ cc structure.c
$ ./a.out 
Inside show function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000
Inside main function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000

Passing addresses of structure variable to a function

This c program is the example of passing the addresses of structure variable to a function.

This programm passing address to a function and prints the entire structure variable using pointer.

#include<stdio.h> 
                                                                                
struct book                                                                     
{                                                                               
  int id;                                                                       
  char *title;                                                                  
  char *author;                                                                 
  float price;                                                                  
};                                                                              
                                                                                
void show(struct book *b1)                                                      
{                                                                               
  printf("Inside show function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1->id, b1->title, b1->author, b1->price);        
}                                                                               
void main()                                                                     
{                                                                               
                                                                                
  struct book  b1 = {1, "book1", "author1", 20.5};                              
  show(&b1);                                                                    
                                                                                
  printf("Inside main function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);            
}  

Output:

$ cc structure.c
$ ./a.out 
Inside show function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000
Inside main function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000

Passing individual structure elements to a function using pointer

This c program is passing the individual structure element 'title' to the show function as pointer and displaying it.

#include<stdio.h>                                                             
                                                                                
struct book                                                                     
{                                                                               
  int id;                                                                       
  char *title;                                                                  
  char *author;                                                                 
  float price;                                                                  
};                                                                              
                                                                                
void show(char *title)                                                          
{                                                                               
  printf("Inside show function");                                               
  printf("\ntitle: %s\n", title);                                               
}                                                                               
void main()                                                                     
{                                                                               
                                                                                
  struct book  b1 = {1, "book1", "author1", 20.5};                              
  show(b1.title);                                                               
                                                                                
  printf("Inside main function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);            
}  

Output:

$ cc structure.c
$ ./a.out 
Inside show function
title: book1
Inside main function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000

Passing individual structure elements to a function using array

This c program is passing the individual structure element 'title' to the show function as array and displaying it.

#include<stdio.h>                                                              
                                                                                
struct book                                                                     
{                                                                               
  int id;                                                                       
  char *title;                                                                  
  char *author;                                                                 
  float price;                                                                  
};                                                                              
                                                                                
void show(char title[30])                                                       
{                                                                               
  printf("Inside show function");                                               
  printf("\ntitle: %s\n", title);                                               
}                                                                               
void main()                                                                     
{                                                                               
                                                                                
  struct book  b1 = {1, "book1", "author1", 20.5};                              
  show(b1.title);                                                               
                                                                                
  printf("Inside main function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);            
}   

Output:

$ cc structure.c
$ ./a.out 
Inside show function
title: book1
Inside main function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000

Passing address of individual structure element to a function

This c program explains how to pass the address of individual structure elements to a function.

Address can be passed using & symbol and value of address can be accessed using * pointer.

#include<stdio.h>                                                              
                                                                                
struct book                                                                     
{                                                                               
  int id;                                                                       
  char *title;                                                                  
  char *author;                                                                 
  float price;                                                                  
};                                                                              
                                                                                
void show(int *id)                                                              
{                                                                               
  printf("Inside show function");                                               
  printf("\naddress of id: %d\n", id);                                          
  printf("value of id: %d\n", *id);                                             
}                                                                               
void main()                                                                     
{                                                                               
                                                                                
  struct book  b1 = {1, "book1", "author1", 20.5};                              
  show(&b1.id);                                                                 
                                                                                
  printf("Inside main function");                                               
  printf("\nbook id\ttitle \t auther \t price \n");                             
  printf("%d\t%s\t%s \t%f\n", b1.id, b1.title, b1.author, b1.price);            
}     

Output:

$ cc structure.c
$ ./a.out 
Inside show function
address of id: 62636304
value of id: 1
Inside main function
book id	title 	 auther 	 price 
1	book1	author1 	20.500000