Problems while finding the distance between two points - c

Question

#include <stdio.h>
int main()
{
int x1;
int x2;
int y1;
int y2;
printf("Enter the value of x1 and y1 %d %d ",x1,y1);
scanf("%d %d",&x1,&y1);
printf("Enter the value of x2 and y2 %d %d ",x2,y2);
scanf("%d %d",&x2,&y2);
int l1=x2-x1;
int l2=y2-y1;
int len1=l1*l1;
int len2=l2*l2;
int length=len1+len2;
int lengthf=sqrt(length);
printf("The length between the points = %d",lengthf);
return 0;
}
I was not expecting the locations of the variables. I have to get the distance between two points.

Answer 1

There are several faults in the code:
x1, y1, x2, and y2 are used uninitialized that invokes UB.
You are losing precision to the actual result by casting a double to an int.
You are missing math.h library.
You don't check for the scanf() values.
Lots of redundant variables.
The code can be rather written this way. Follow the comments to understand.
#include <math.h>
#include <stdio.h>
#define EXIT_SUCCESS 0
#define EXIT_FAILURE 1
// Storing the coordinate values in a structure.
struct point {
int x;
int y;
};
int main(void)
{
struct point p1 = { 0, 0 };
struct point p2 = { 0, 0 };
fprintf(stdout, "Enter the value of x1 and y1: ");
// Validation of input -- considered good practices.
if (fscanf(stdin, "%d %d", &p1.x, &p1.y) != 2) {
fprintf(stderr, "error: The value(s) are invalid.\n");
return EXIT_FAILURE;
}
fprintf(stdout, "Enter the value of x2 and y2: ");
// Validation of input -- considered good practices.
if (fscanf(stdin, "%d %d", &p2.x, &p2.y) != 2) {
fprintf(stderr, "error: The value(s) are invalid.\n");
return EXIT_FAILURE;
}
// Finally, evaluation of the distance using pow() and sqrt().
double distance = sqrt(pow(p2.x - p1.x, 2) + pow(p2.y - p1.y, 2));
fprintf(stdout, "Distance between two points: %.2lf\n", distance);
return EXIT_SUCCESS;
}