Easy tutorial for C / C ++ - struct 2 (Initial values of struct variables, function arguments, return value)

Easy tutorial for C / C ++ - struct 2 (Initial values of struct variables, function arguments, return value)

- Let's look at how to give initial values to struct variables. The struct defined in the previous example is:

struct t_Struct{

   int num;

   char fruit[30];

   char color[30];

};

- Member variables are integer variable 'num' and string variables 'fruit' and 'color'. Initialization can be done by member variable as follows. Separate it with a comma (,) and enclose it in curly braces ({}).

ex) :

t_Struct strA = {5, "banana","white"};

- A struct can be used as a function's return value and return value. Let's look at an example.

Example Code

#include <iostream>

using namespace std;

struct t_Struct{

   int num;

   char fruit[30];

   char color[30];

};

void prn_1(t_Struct);

t_Struct prn_2();

int main() {

     t_Struct strA = {5, "banana","white"};

     cout << "*** \'prn_1\' results (1st) ***" << endl;

     prn_1(strA);

     strA = prn_2();

     cout << "*** \'prn_1\' results (2nd) ***" << endl;

     prn_1(strA);

     return 0;

}

void prn_1(t_Struct AA)

{

          cout << " number = " << AA.num << endl ;

          cout << " fruit  = " << AA.fruit << endl ;

          cout << " color  = " << AA.color << endl ;

          cout << endl;

}

t_Struct prn_2()

{

     t_Struct BB = {7, "apple", "green"} ;

     return BB;

}

- We defined a structure 't_Struct' which has integer variable 'num' and string variables 'fruit' and 'color' as member variables.

(1) We declare an output function that takes the struct 't_Struct' as an argument and has no return value. (void prn_1 (t_Struct);) This function outputs the contents of the member variables of the struct variable received as an argument.

(2) We declared a function with no argument and a return value of struct 't_Struct'. (t_Struct prn_2 ();) This function declares and initializes a struct variable ('BB') and returns {7, "apple", "green"} structure variables.

- Declared a struct variable 'strA' in the main function and initialized it with {5, "banana", "white"}. We then called the function 'prn_1' and passed 'strA' as an argument.

- Called 'prn_2 ()' and assigned to 'strA'. And once again we call the function 'prn_1' and pass 'strA' as an argument.

results :

*** 'prn_1' results (1st) ***

 number = 5

 fruit  = banana

 color  = white

*** 'prn_1' results (2nd) ***

 number = 7

 fruit  = apple

 color  = green

- As a result of the first output, we can see that the initial value 5, banana, white of the struct variable strA is output.

- The function 'prn_2 ()' is called and the returned value is assigned to 'strA'. As a result, we can see that the initial value 7, apple, green of the struct variables defined in the 'prn_2 ()' function is output.