C Programming - Const - Discussion

I think in this case e1.name is initialized by garbage values, e1.age/salary initialized by 0.

So, we can not modify any one of them, but by using strcpy function we can modify e1.name indirectly by using a pointer and this is valid.

strcpy function :
char* strcpy(char* destination, const char* source);

@ALL.

#include<stdlib.h>

union employee
{
char name[15];
int age;
float salary;
};
const union employee e1;

int main()
{
e1.age=18;
printf("%s", e1.name);
printf("%d", e1.age);
printf("%f", e1.salary);
return 0;
}

Why does it take name but not age?

#include<stdio.h>
#include<stdlib.h>

union employee
{
char name[15];
int age;
float salary;
};
const union employee e1;

int main()
{
strcpy(e1.name, "K");
printf("%s", e1.name);
printf("%d", e1.age);
printf("%f", e1.salary);
return 0;
}

This is valid.

Why doesn't that give error as the const variable can't be modified, it does give error in other data types constant but why not here ?

@Venkatesh.

Even though if we initialized e.salary to a number we get 0 as output, this is because we initialized e.age as integer type, so if we want to print e.salary (float type) we get 0.000000 as output.

Compile this:

#include<stdio.h>
#include<stdlib.h>

union employee
{
char name[15];
int age;
float salary;
};
union employee e1;

int main()
{
strcpy(e1.name, "K");
printf("%s\n", e1.name);
e1.salary=95;
e1.age=85;
printf("%f", e1.salary);
return 0;
}

@Venkatesh:

The value stored in e.age is integer type, so if we want to print integer variable into float variable in printf statement, it is automatically initialized to 0.

@Venkatesh:

You have not initialized salary variable.

By default compiler will initialize variable according to type.

As salary is float, it it initialized as 0.000000.

#include<stdio.h>
#include<stdlib.h>

union employee
{
char name[15];
int age;
float salary;
};
union employee e1;

int main()
{
strcpy(e1.name, "K");
printf("%s\n", e1.name);
e1.age=85;
printf("%d\n", e1.age);
printf("%f", e1.salary);
return 0;
}

Now the above program is giving output as:
K
85
0.000000

Why 0.000000 is coming?

A const variable must be initialized during the declaration itself.

Because its union in union different variable stores at same location, So in program the value supplied to char name[] variable will be stored at location which will be shared by all other union members so the ASCII value of 'k' 75 will be stored, and 'int age' variable also will be having 75 because the memory location of 'char name[]' & 'int age' is same, as we declared union as constant so if you try to change the value 75 to 85 it will give an error.

I cant understand. please anyone help me...