Initializing a string and passing it to a function [duplicate] - c

Question

This question already has answers here:
Can I initialize string after declaration?
(3 answers)
Closed 2 years ago.
In this code I tried to initialize and pass three strings to a function: action_type; system_type; room
(COLD, HOT, and EMP mean respectivly cooling system, hotting system and employee room).
The code code runs but it doesn't printf the strings. What can I do in order to visualize the strings?
Thanks all.
enter code here
#include <stdio.h>
#include <string.h>
#define T_MAX_EMP 25
#define T_MIN_EMP 15
#define ON 1
#define OFF 0
void SystemAction(char* action_type, char* system_type, char* room, bool power)
{
if(power == OFF)
{
printf ("%s %s %s \n", action_type, system_type, room);
power = ON;
}
else
{
if(power == ON)
{
printf("%s is still on \n", system_type);
}
}
}
void SystemCheck(int n, int system)
{
if(n == 1)
{
printf ("The heating / cooling system works correctly \n");
}
else
{
if(n == 0)
{
printf("System malfunctions have been reported \n");
system = n;
}
else
{
printf ("\n Value entered is incorrect \n");
}
}
}
int main()
{
int n;
int system = 1;
int ch;
int power = OFF;
char c;
char action_type[10];
char system_type[10];
char room[10];
do
{
printf("Enter the character and the integer: \n");
scanf (" %c %d" , &c, &n);
switch(c)
{
case 'e' :
if(system == 0)
{
printf("The system doesn't work \n");
}
else
{
if (n > T_MAX_EMP)
{
action_type[10] = "ON";
system_type[10] = "COLD";
room[10] = "EMP";
SystemAction(action_type, system_type, room, power);
}
else
{
if(n < T_MIN_EMP)
{
action_type[10] = "ON";
system_type[10] = "HOT";
room[10] = "EMP";
SystemAction(action_type, system_type, room, power);
}
}
break;
}
case 's' :
SystemCheck(n, system);
break;
}
printf("Continue? \n");
scanf(" %d", &ch);
}while(ch == 1);
return 0;
}

Answer 1

action_type[10] = "ON"; is not the proper way to assign strings.
You didn't get that code from any reference, book, training material.
Did you make up an entirely new syntax hoping it would work?
Look into strcpy

Answer 2

Arrays do not have the assignment operator.
In statements like these
action_type[10] = "ON";
system_type[10] = "COLD";
room[10] = "EMP";
it seems you want to assign arrays with string literals. However actually you are trying to assign non-existent elements of the arrays with pointers to first characters of the string literals.
What you need is to copy the string literals into arrays like
strcpy( action_type, "ON" );
strcpy( system_type, "COLD" );
strcpy( room, "EMP" );
If You are not going to change elements of the arrays then instead of arrays of characters you could use just pointers like
char *action_type;
char *system_type;
char *room;
In this case the statements like these
action_type = "ON";
system_type = "COLD";
room = "EMP";
will be correct.
Or even to declare the pointers with the qualifier const
const char *action_type;
const char *system_type;
const char *room;
In this case you will need also to change the function declaration
void SystemAction(char* action_type, char* system_type, char* room, bool power);
to the following declaration
void SystemAction( const char* action_type, const char* system_type, const char* room, bool power);

Answer 3

Firstly, your code have to #include <stdbool.h> for bool type.
Secondly, You should use strcpy for copying string to string in c.
strcpy(action_type,"ON");
strcpy(system_type,"COLD");
strcpy(room,"EMP");
and
strcpy(action_type,"ON");
strcpy(system_type,"HOT");
strcpy(room,"EMP");
When you use action_type[10] for example, this is 11th character of array action_type. "ON" is string not character. If you want to assign with character, use ' instead of ". For example
action_type[0] = 'O';
action_type[1] = 'N';
action_type[3] = '\0';
One more thing, action_type[10] is out of the array because the maximum index of action_type is 9 (from 0 to 9).