C Programming

Solved Example

Practice Questions

Exercise Question

Check the points are co-linear or not


Input coordinates for 3 points (x1,y1), (x2,y2) and (x3,y3). Write a program to check that all points are fall in one straight line or not.

Program / Solution:


int main() {
	int x1,y1,x2,y2,x3,y3;
	int s1,s2,s3;
	printf("Enter first point (x1,y1): ");
	printf("Enter second point (x2,y2): ");
	printf("Enter third point (x3,y3): ");
	s1 = abs(x2 - x1) / abs(y2 - y1); //slop between point-1 and point-2
	s2 = abs(x3 - x2) / abs(y3 - y2); //slop between point-2 and point-3
	s3 = abs(x3 - x1) / abs(y3 - y1); //slop between point-3 and point-1
	if((s1 == s2) && (s2 == s3)) {
		printf("Points are co-linear");
	}else {
		printf("Points are not co-linear");
	return 0;

Sample Output:

Enter first point (x1,y1): 1 1
Enter second point (x2,y2): 2 2
Enter third point (x3,y3): 3 3
Points are co-linear

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