runner$ cat -n example0.c
     1  /* Volume of a sphere of radius r */
     2  #include <stdio.h>
     3  #define pi 3.14159265358979;
     4  int main()
     5  {
     6          double r, vol;
     7          /* input the radius r */
     8          scanf("%lf", r);
     9          /* calculate the volume */
    10          vol = (4/3)*pi*r*r*r;
    11          /* print radius and volume */
    12          printf("Radius:%10.6f, Volume:%10.6f\n", r, vol);
    13          return 0;
    14  }
runner$ lint -m -u example0.c
(8) warning: variable may be used before set: r
(10) error: cannot dereference non-pointer type

statement has null effect
    (10)            
lint: errors in example0.c; no output created
lint: pass2 not run - errors in example0.c
runner$ cat -n example1.c
     1  /* Volume of a sphere of radius r */
     2  #include <stdio.h>                 /***************************/
     3  #define pi 3.14159265358979        /* NOTE: SEMICOLON DELETED */
     4  int main()                         /***************************/
     5  {
     6          double r, vol;
     7          /* input the radius r */          /********************/
     8          scanf("%lf", &r);                 /* NOTE: & INSERTED */
     9          /* calculate the volume */        /********************/
    10          vol = (4/3)*pi*r*r*r;
    11          /* print radius and volume */
    12          printf("Radius:%10.6f, Volume:%10.6f\n", r, vol);
    13          return 0;
    14  }
runner$ lint -m -u example1.c
function returns value which is always ignored
    printf              scanf           
runner$ cc -o example1 example1.c
runner$ example1
1.0
Radius:  1.000000, Volume:  3.141593          (NOTE: WRONG ANSWER!)
runner$ cat example2.c
/* Volume of a sphere of radius r */
#include <stdio.h>
#define pi 3.14159265358979

int main()
{
        double r, vol;
        /* input the radius r */
        scanf("%lf", &r);
        /* calculate the volume */      /******************************/
        vol = (4.0/3.0)*pi*r*r*r;       /* NOTE: (4/3) NOW  (4.0/3.0) */
        /* print radius and volume */   /******************************/
        printf("Radius:%10.6f, Volume:%10.6f\n", r, vol);
        return 0;
}
runner$ example2
1.0
Radius:  1.000000, Volume:  4.188790
runner$ example2
10.0
Radius: 10.000000, Volume:4188.790205