1 Chapter 2: Data Types & Operations Part 1 ICS101: Computer Programming Al-Hashim, Amin G.

2 Outline  Data Types  Constants  Variables

3 Data Types  Data: form of recording  4 basic types of data in FORTRAN:  Integer  Real  Character  Logical

4 Constants  Fixed value  Types:  Integer constants  Real constants  Character constants  Logical constants

5 Integer Constants  Numbers without a decimal point  E.g.:  101 00   1429

6 Real Constants  Numbers with a decimal point  E.g.:  3.4     Representations in FORTRAN:  Ordinarily  Scientific Notation xEy (0.1≤ x <1.0) …

7 Character Constants  Any set of characters between single quotes  E.g.:  ‘FORTRAN is an interesting PL’  ‘I’’am very interesting with ICS101’

8 Logical Constants  2 logical constants in FORTRAN: .TRUE. represents true .FALSE. represents false

9 Variables  Occupies a place at the computer memory  Must have a name to be referenced  Its value can be changed

10 Cont.  Rules of Naming Variables:  Starts with an alphabetic character  May contain digits  Should not contain special characters  Length should not exceed 6 characters  Must not contain blanks  Which of the following are legal variable names? (1) FIVE (2) 5IVE (3) F!VE (4) F I V E (5) FIVE55555 (6) F5

11 Cont.  Types of Variables :  Integer variables  Real variables  Character variables  Logical variables

12 Integer Variables  Hold only integer values  Definition:  Explicit … using the INTEGER statement INETGER X, Y, Z, FIVE  Implicit … variable name starts with I, J, K, L, M, or N ISUM, JAR, KILO  MUST be before any executable statement

13 Real Variables  Hold only real values  Definition:  Explicit … using the REAL statement REAL TAX, FEE, Z, FIVE  Implicit … variable name doesn’t start with I, J, K, L, M, or N SLOPE, WEIGHT, F6  MUST be before any executable statement

14 Character Variables  Hold only character values  Definition:  Explicit ONLY… using the CHARACTER statement CHARACTER NAME*6, COL*10, MAJOR CHARACTER*6 NAME, COL*10, MAJOR  MUST be before any executable statement

15 Logical Variables  Hold only logical values (.TRUE. |.FALSE.)  Definition:  Explicit ONLY… using the LOGICAL statement LOGICAL FLAG, TEST, X, CONT  MUST be before any executable statement

16 Exercise  Find the errors in the following FORTRAN code * FullOfErrors.for C By: Al-Hashim INTEGER OFFICE#, HOURS, MINUTES SECONDS CHARACTER *100LOGIC FLAG PRINT*, ICS101: COMPUTER PROGRAMMING REAL CASH1, CASH2