FORTRAN EXAM QUESTIONS AND VERIFIED
ANSWERS
Original Design Goal for original FORTRAN - ANSWER 1. Efficiency
2. A HLL for Numerical Engineering Applications
How is storage set in Fortran? - ANSWER All needed storage of the
program is decided at compile time, with minimal invocation of the OS
Fortran Typing System? - ANSWER Simple Typing system, static, and
few types: integer, real, complex, double, and arrays
Is there type definitions? - ANSWER No type definition or facilitating
user-defined data abstractions, only arrays and fixed size char string, in
addition to adding Subroutines and Functions abstraction.
What is put in the FORTRAN Declarative Section? - ANSWER i)
Allocating memory locations of specified sizes (based on the name
declared type) to hold the values of such declared names; and bind the
declared names to the assigned locations, statically (in FORTRAN), for
the entire life cycle of the program execution.
ii) Possibly, assigning initial value (if given) to the name's allocated
memory space.
What is put in the Imperative Section of FORTRAN? - ANSWER i)
Computational: X = Y/Z + F(4) + ARY(15)
ii) Control Flow: GO TO, DO .. CONTINUE, IF ( L1, L2, L3) I, CALL
SUB1(X,Y,Z),...
iii) Input/Output: READ, PRINT.
Unconditional GO TO - ANSWER GO TO label
Computed GO TO - ANSWER GO TO (L1, L2, ..., Ln), I
, If I = k, jump to Lk label in the label list, 1 <= k <= n; otherwise no jump.
Assigned GO TO - ANSWER GO TO N, (L1, L2, ..., Ln)
Go to the address placed in N, hence N must be pre-assigned some
label address, via the assign statement "ASSIGN <label> TO <id=N>",
that places the address of the label into the id N. It is the responsibility of
the programmer to do so (leads to insecurity).
FORTRAN's Security Loophole - ANSWER The similarity of the
computed and assigned "GO TO" above. In addition to the overworking
of the integer type to carry label's address and integers (weak typing),
and trusting the "user" to use the assign statement before any assigned
"GO TO" would introduce a great possibility of the CPU jumping to
execute at an unknown place in memory
Golden Rules learned from Fortran - ANSWER 1)"Different semantics
HLL's elements/structures should be expressed in Different syntax" (Not
always--> Exceptions? Why?).
2) The compiler should NOT trust the HLLs' users to do the right thing.
What is a Type - ANSWER A type of a variable is the set of values that
such variable can have and the set of operations that can work on such
values.
Why do we need Types in some HLLs? - ANSWER 1) Efficient
allocation of memory
2) Type Checking (security)
Two major Type Classifications - ANSWER 1) Built-in system: basic
types-- integer, real, etc, and structured—array, records, files,..
2) User defined: ADTs, Classes, Modules, Packets
Type "Coercion" - ANSWER Implicit type conversion based on the
context of use.
ANSWERS
Original Design Goal for original FORTRAN - ANSWER 1. Efficiency
2. A HLL for Numerical Engineering Applications
How is storage set in Fortran? - ANSWER All needed storage of the
program is decided at compile time, with minimal invocation of the OS
Fortran Typing System? - ANSWER Simple Typing system, static, and
few types: integer, real, complex, double, and arrays
Is there type definitions? - ANSWER No type definition or facilitating
user-defined data abstractions, only arrays and fixed size char string, in
addition to adding Subroutines and Functions abstraction.
What is put in the FORTRAN Declarative Section? - ANSWER i)
Allocating memory locations of specified sizes (based on the name
declared type) to hold the values of such declared names; and bind the
declared names to the assigned locations, statically (in FORTRAN), for
the entire life cycle of the program execution.
ii) Possibly, assigning initial value (if given) to the name's allocated
memory space.
What is put in the Imperative Section of FORTRAN? - ANSWER i)
Computational: X = Y/Z + F(4) + ARY(15)
ii) Control Flow: GO TO, DO .. CONTINUE, IF ( L1, L2, L3) I, CALL
SUB1(X,Y,Z),...
iii) Input/Output: READ, PRINT.
Unconditional GO TO - ANSWER GO TO label
Computed GO TO - ANSWER GO TO (L1, L2, ..., Ln), I
, If I = k, jump to Lk label in the label list, 1 <= k <= n; otherwise no jump.
Assigned GO TO - ANSWER GO TO N, (L1, L2, ..., Ln)
Go to the address placed in N, hence N must be pre-assigned some
label address, via the assign statement "ASSIGN <label> TO <id=N>",
that places the address of the label into the id N. It is the responsibility of
the programmer to do so (leads to insecurity).
FORTRAN's Security Loophole - ANSWER The similarity of the
computed and assigned "GO TO" above. In addition to the overworking
of the integer type to carry label's address and integers (weak typing),
and trusting the "user" to use the assign statement before any assigned
"GO TO" would introduce a great possibility of the CPU jumping to
execute at an unknown place in memory
Golden Rules learned from Fortran - ANSWER 1)"Different semantics
HLL's elements/structures should be expressed in Different syntax" (Not
always--> Exceptions? Why?).
2) The compiler should NOT trust the HLLs' users to do the right thing.
What is a Type - ANSWER A type of a variable is the set of values that
such variable can have and the set of operations that can work on such
values.
Why do we need Types in some HLLs? - ANSWER 1) Efficient
allocation of memory
2) Type Checking (security)
Two major Type Classifications - ANSWER 1) Built-in system: basic
types-- integer, real, etc, and structured—array, records, files,..
2) User defined: ADTs, Classes, Modules, Packets
Type "Coercion" - ANSWER Implicit type conversion based on the
context of use.
