lab5_4 งานท้ายบทข้อ1

#include<stdio.h>

int abc(int x);
int main()
{
    int x;
    printf("f(x) = x2 + 2x + 3 if x < 0 \nf(x) = 0           if x = 0\nf(x) = x - 2       if x > 0");
    printf("\nEnter number :");
    scanf("%d",&x);
    abc(x);
    return 0;
}
int abc(int x)
{
    int y;
    if(x<0){
        printf("f(x) = x2 + 2x + 3\nf(%d) = %d",x,(x*x)+(x*2)+3);
    }
    else if(x==0){
        printf("f(x) = 0 \nf(%d) = %d",x,0);
    }
    else{
        printf("f(x) = x - 2 \nf(%d) = %d",x,x-2);
    }
}