18.(C) Finding whether a number is positive ,negative or zero

 #include<stdio.h>

int main(){

    int a;

    printf("Enter a\n");

    scanf("%d",&a);

    if(a>0){

        printf("a is positive ");

    }

     if(a<0){

        printf("a is negative");

    }

    if(a==0)

    {

       printf("a is zero ");

    }

    return 0;

}