L-Value Error

Question

#include <stdio.h>
 
int make_it(int *x,int *y, int *z){
	*x *= *y+*z;
	*y=*x<<1;
	*z=*x+*y;
}
 
 
int main(void) {
	int a=5, b=10;
	printf("%d%d",a,b);
	make_it(&b,&a,&(a+b));
	printf("%d%d",a,b);
	return 0;
}

Why this code is giving lvalue error?

Comments

make it() function will require address of integer variable , but you are sending &(a+b)

$a+b$ is not stored in any variable

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yes thank u :)

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i hope a+b stored in stack as temp variable... But what is the purpose of it?? Isn't to provide r value only??? Just like address of array and value of array i mean ( a and &a where a is array of integers variable ) because of that it will give error on line *z = *x+*y

Answer 1

int main(void) {
	int a=5, b=10;
	printf("%d%d",a,b);
	make_it(&b,&a,&(a+b));  <== Here &(a+b) returns the error.
	printf("%d%d",a,b);
	return 0;
}

Since you have declared a and b as integers, a+b returns an integer value (not a variable). So the unary & fails because no address is available. Check the example below:

#include <stdio.h>

int main()
{
     int a=5,b=10;
    printf("%d", &(a+b));

    return 0;
}

$gcc -o main *.c
main.c: In function ‘main’:
main.c:7:18: error: lvalue required as unary ‘&’ operand
     printf("%d", &(a+b));
                  ^