Compiler HW

array.c

/* array.c  -- Operations on arrays
 */

#include <stdio.h>

int main(void) {
  int a[2] = {1,2};  /* The aggregates like {1,2} are literals for arrays */
  int b[2] = {2,3};
  int i;

  /* It is legal to use subscripts on arrays, both on the left and on 
   * the right hand side of assignments. */
  for(i=0;i<2;i++)
    a[i]=b[i];

  /* It is not legal to assign arrays, like in a=b; */

  /* The comparison of two distinct arrays with the same content
   * results in FALSE. So below we print "They are not equal"
   */
  if(a==b)
    printf("They are equal\n");
  else
    printf("They are not equal\n");

  /* The following comparison results in TRUE. */
  if(a==a)
    printf("Of course a is equal to a\n");
  else
    printf("No, a is not equal to a\n");
  /* The behavior of comparison is explained when we note that the
   * comparison is a comparison of addresses, not contents.
   */
  /* We cannot print out an array as a single unit. We have to print out
   * its elements one at a time.
   */
  for(i=0;i<2;i++)
    printf("a[%1d] = %3d\n", i, a[i]);
}

output

:=
  []
    <id:a> (node id=2)
    <int:0> (node id=5)
  <int:1> (node id=0)

:=
  []
    <id:a> (node id=2)
    <int:1> (node id=0)
  <int:2> (node id=1)

:=
  []
    <id:b> (node id=9)
    <int:0> (node id=5)
  <int:2> (node id=1)

:=
  []
    <id:b> (node id=9)
    <int:1> (node id=0)
  <int:3> (node id=8)


:=
  <id:i> (node id=14)
  <int:0> (node id=5)

<
  <id:i> (node id=14)
  <int:2> (node id=1)

++
  <id:i> (node id=14)

:=
  []
    <id:a> (node id=2)
    <id:i> (node id=14)
  []
    <id:b> (node id=9)
    <id:i> (node id=14)



==
  <id:a> (node id=2)
  <id:b> (node id=9)

printf
  printf format
    <str:They are equal> (node id=22)
    printf format
      <str:(newline)> (node id=23)

printf
  printf format
    <str:They are not equal> (node id=27)
    printf format
      <str:(newline)> (node id=23)

==
  <id:a> (node id=2)
  <id:a> (node id=2)

printf
  printf format
    <str:Of course a is equal to a> (node id=32)
    printf format
      <str:(newline)> (node id=23)

printf
  printf format
    <str:No, a is not equal to a> (node id=36)
    printf format
      <str:(newline)> (node id=23)





:=
  <id:i> (node id=14)
  <int:0> (node id=5)

<
  <id:i> (node id=14)
  <int:2> (node id=1)

++
  <id:i> (node id=14)

printf
  printf format
    <str:a[> (node id=43)
    printf format
      <format specifier> (node id=44)
      printf format
        <str:] = > (node id=45)
        printf format
          <format specifier> (node id=46)
          printf format
            <str:(newline)> (node id=23)
  printf arg
    <id:i> (node id=14)
    printf arg
      []
        <id:a> (node id=2)
        <id:i> (node id=14)