Error in the program & I need some programs. Can you help me

in this program there error i don't know where!! and i need the out put from it .

#include<stdio.h>
void main(void)
void change(void);
int x=4,y;
y=x;
{
printf("\n The value of x is = %f and the value of y is = %d",x,y);
change();
printf("\n The value of x is = %d and the value of y is = %d ",x,y);
}
void change(void)
{
x=x+3;
}

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and i need this programs plz .. can u help me

(a) Write a C program that uses two user defined functions, one of the functions calculates the sum and the other calculates the product of two numbers.
(b) Write a C program that uses pointers to calculate the sum of the elements of an array.
(c) Write a C program that declares and initializes two variables and then write their values on a file.

 

no help

 

1. Correct definiton

Code:

int y,x=4;

2. Assignment instruction must be in a function

Code:

int main()
{
  y=x;
  // other instructions
  return 0;
}

3. Why do you want to display integer value as floating-point?

Code:

printf("\n The value of x is = [COLOR="Red"]%f[/COLOR] and the value of y is = %d",x,y);

4.

Compile and run the program.