#include <stdio.h>
#include <stdlib.h>
#define BUSI 256
#define N 2
int main(void)
{
char buf[BUSI];
int u[N];
int v[N];
int i,sum;
for(i=0 ; i < N ; i++) {
printf("input u[%d]",i);
fgets(buf,BUSI,stdin);
u[i] = atoi(buf);
}
for(i=0 ; i < N ; i++) {
printf("input v[%d]",i);
fgets(buf,BUSI,stdin);
v[i] = atoi(buf);
}
printf("u=[");
for(i=0 ; i < N ; i++) {
printf("%2d",u[i]);
}
printf(" ], ");
printf("v=[");
for(i=0 ; i < N ; i++) {
printf("%2d",v[i]);
}
printf(" ]\n");
sum = 0;
sum = innerProduct(u[N],v[N]);
printf("inner product is %d",sum);
if(sum>0){
printf("The angle of the vectors is less than 90 degree.");
}else if(sum==0){
printf("The angle of the vectors is 90 degree.");
}else{
printf("The angle of the vectors is greater than 90 degree.");
}
printf("\n");
return 0;
}
int innerProduct(int u[],int v[])
{
int i,total;
total = 0;
for(i=0 ; i < N ; i++) {
total += u[i]*v[i];
}
return total;
}