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OpenVMS Debugger Manual
C.17.2 Constructs in Language and Address Expressions
Supported constructs in language and address expressions for language
UNKNOWN follow:
| Symbol |
Construct |
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[ ]
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Subscripting
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( )
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Subscripting
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. (period)
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Record component selection
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^ (circumflex)
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Pointer dereferencing
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C.17.3 Predefined Symbols
Supported predefined symbols for language UNKNOWN follow:
| Symbol |
Meaning |
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TRUE
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Boolean True
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FALSE
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Boolean False
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NIL
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Nil pointer
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C.17.4 Data Types
When the language is set to UNKNOWN, the debugger understands all data
types accepted by other languages except a few very language-specific
types, such as picture types and file types. In UNKNOWN language
expressions, the debugger accepts most scalar OpenVMS calling standard
data types.
- For language UNKNOWN, the debugger accepts the dot-notation for
record component selection. For example, if C is a component of a
record B which in turn is a component of a record A, then C can be
referenced as A.B.C. Subscripts can be attached to any array
components; for example, if B is an array, then C can be referenced as
A.B[2,3].C.
- For language UNKNOWN, the debugger accepts brackets and parentheses
for subscripts. For example, A[2,3] and A(2,3) are equivalent.
Appendix D
EIGHTQUEENS.C
This appendix contains the source code for the programs used in many
figures of Chapter 8, Chapter 9, and Chapter 10,
EIGHTQUEENS.C AND 8QUEENS.C. These programs are presented here only to
assist in understanding the procedures described in those chapters.
D.1 EIGHTQUEENS.C
Example D-1 contains EIGHTQUEENS.C, the single-module program that
solves the eightqueens problem.
| Example D-1 Single-Module Program
EIGHTQUEENS.C |
extern void setqueen();
extern void removequeen();
extern void trycol();
extern void print();
int a[8]; /* a : array[1..8] of boolean */
int b[16]; /* b : array[2..16] of boolean */
int c[15]; /* c : array[-7..7] of boolean */
int x[8];
/* Solve eight-queens problem */
main()
{
int i;
for (i=0; i <=7; i++)
a[i] = 1;
for (i=0; i <=15; i++)
b[i] = 1;
for (i=0; i <=14; i++)
c[i] = 1;
trycol( 0 );
} /* End main */
void trycol( j )
int j;
{
int m;
int safe;
m = -1;
while (m++ < 7)
{
safe = (a[m] ==1) && (b[m + j] == 1) && (c[m - j + 7] ==1);
if (safe)
{
setqueen(m, j);
x[j] = m + 1;
if (j < 7)
trycol(j + 1);
else
print();
removequeen(m, j);
}
}
} /* End trycol */
void setqueen(m, j)
int m;
int j;
{
a[m] = 0;
b[m + j] = 0;
c[m - j + 7] = 0;
} /* End setqueen */
void removequeen(m, j)
int m;
int j;
{
a[m] = 1;
b[m + j] = 1;
c[m - j + 7] = 1;
} /* End removequeen */
void print()
{
int k;
for (k=0; k<=7; k++)
{
printf(" %d", x[k]);
}
printf("\n");
} /* End print */
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D.2 8QUEENS.C
8QUEENS.C is the multiple-module program that solves the eightqueens
problem. This program consists of two modules, 8QUEENS.C
(Example D-2) and 8QUEENS_SUB.C (Example D-3).
| Example D-2 Main Module 8QUEENS.C |
extern void trycol();
int a[8]; /* a : array[1..8] of boolean */
int b[16]; /* b : array[2..16] of boolean */
int c[15]; /* c : array[-7..7] of boolean */
int x[8];
main() /* Solve eight-queens problem */
{
int i;
for (i=0; i <=7; i++)
a[i] = 1;
for (i=0; i <=15; i++)
b[i] = 1;
for (i=0; i <=14; i++)
c[i] = 1;
trycol(0);
printf(" Solved eight-queens problem!\n");
} /* End main */
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| Example D-3 Submodule 8QUEENS_SUB.C |
extern int a[8];
extern int b[16];
extern int c[15];
extern void setqueen();
extern void removequeen();
extern void print();
int x[8];
void trycol( j )
int j;
{
int m;
int safe;
m = -1;
while (m++ < 7)
{
safe = (a[m] ==1) && (b[m + j] == 1) && (c[m - j + 7] ==1);
if (safe)
{
setqueen(m, j);
x[j] = m + 1;
if (j < 7)
trycol(j + 1);
else
print();
removequeen(m, j);
}
}
} /* End trycol */
void setqueen(m, j)
int m;
int j;
{
a[m] = 0;
b[m + j] = 0;
c[m - j + 7] = 0;
} /* End setqueen */
void removequeen(m, j)
int m;
int j;
{
a[m] = 1;
b[m + j] = 1;
c[m - j + 7] = 1;
} /* End removequeen */
void print()
{
int k;
for (k=0; k<=7; k++)
{
printf(" %d", x[k]);
}
printf("\n");
} /* End print */
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