Transcript CHAPTER 5 INPUT/OUT FORMAT Introduction READ (*,*) x WRITE (*,*) x • This is free format: the first * is for I/O device number (* =

CHAPTER 5
INPUT/OUT FORMAT
Introduction
READ (*,*) x
WRITE (*,*) x
• This is free format: the first * is for I/O
device number (* = input is keyboard
* = output is the screen)
• The second * means free format
• Input devices: keyboard, files
• Output devices: screen, printer, files
Formatting Descriptors (Fields)
I field for integers
********************************
Integer :: index=-12,junk=4,number = -12345
Write (*,200) index, index+12, junk, number
100 FORMAT (‘ ‘,2I5, I6,I10)
**********************OR **********
Integer :: index=-12,junk=4,number = -12345
Write (*,’(1x,2I5, I6,I10)’) index,index+12,junk,number
******************************************
READING is similar to WRITING EXCEPT writing is rightjustified. In reading the numbers anywhere within the field
length are read
F
Descriptors (for REAL)
REAL:: a =12.3, b =.123, c=123.456
WRITE (*,100) a,b,c
100 FORMAT (‘ ‘,3F10.2)
**************************************************
READING is similar to writing EXCEPT, writing is
right-justified. In reading the numbers anywhere
within the field length are read.
Also it is important to insert the decimal point for
the variable to be read.
E
Descriptors (for exponential
REAL)
• For large and small numbers
REAL :: a =1.2346E6, b=0.001, c=-77.7E10
REAL :: d =-77.7E10
WRITE (*,’(1x, 2E14.4,E13.6,E11.6)’)a,b,c,d
OUTPUT
0.1235E+07 0.1000E-02- 0.777000E+12***********
*******************************************
Length of field w at least 7 + number of digits after decimal point
1 for sign of mantissa (e.g. -0.777000e12), 2 for zero and decimal point, 1 for
E, 1 for sign of exponent, 2 for exponent itself)
***************************************************************************
READING is similar to writing EXCEPT, writing is right-justified. In
reading the numbers anywhere within the field length are read.
Also it is important to insert the decimal point and show the exponent
for the variable to be read.
ES Descriptors (for exponential REAL
Using Scientific and Engineering
Notations)
• Similar to E descriptor
• For large and small numbers
REAL :: a =1.2346E6, b=0.001, c=-77.7E10
REAL :: d =-77.7E10
WRITE (*,’(1x, 2ES14.4,ES13.6,ES11.6)’)a,b,c,d
OUTPUT
1.2346E+06
1.0000E-03-7.770000E+11***********
A Descriptors (for Characters)
Character (len = 17)::name=‘this is a mohamed’
Character (len = 17)::name='this is a mohamed'
Write (*,10) name
Write (*,11)name
Write (*,12) name
10 format (' ',A)
11 format (' ',A20)
12 Format (' ',A6)
******************************
this is a mohamed
this is a mohamed
this i
• **************************************************************
A Descriptors (for Characters)
Character (len=10):: string_1, string_2
Character (len=5) :: string_3 ; character (len=15):: string_4,string_5
Read (*,’(A)’)string_1; Read (*,’(A10)’)string_2; Read (*,’(A10)’)string_3
Read (*,’(A10)’)string_4; Read (*,’(A)’)string_5
Write (*,*) string_1,string_2,string_3,string_4,string_5
********************************************
Input:
abcdefghijklmno
abcdefghijklmno
abcdefghijklmno
abcdefghijklmno
Abcdefghijklmno
*******************************
Output:
abcdefghij
abcdefghij
fghij
abcdefghij
abcdefghijklmno
Other Descriptors
• X = for space
• T = for position
• / = for new line
Reading from a file
OPEN (UNIT=3, FILE=‘input’, STATUS='OLD', ACTION='READ', &
IOSTAT=status )
Read (3,*) x
readloop: DO
READ (3,*,IOSTAT=status) value ! Get next value
IF ( status /= 0 ) EXIT
! EXIT if not valid.
nvals = nvals + 1
! Valid: increase count
WRITE (*,1010) nvals, value
! Echo to screen
FORMAT (' ','Line ', I6, ': Value = ',F10.4 ) 1010
END DO readloop
CLOSE ( UNIT=3 )
Writing to file
OPEN (UNIT=4, FILE=‘output’, STATUS=‘NEW', ACTION=‘WRITE', &
IOSTAT=status )
Write 4,100) x,y,z
100 format (1x,” x = “, f10.2, “ y = “, f10.2, “
z = “, f10.2)
Example
PROGRAM table
IMPLICIT NONE
INTEGER :: cube
! The cube of i
INTEGER :: i
! Index variable
INTEGER :: square
! The square of i
REAL :: square_root ! The square root of i
OPEN(UNIT=10,FILE='table.txt',STATUS='unknown')
! Print the title of the table.
WRITE (10,100)
100 FORMAT (1x, T4, 'Table of Square Roots, Squares, and Cubes')
! Print the column headings after skipping one line.
WRITE (10,110)
110 FORMAT (1x, T4,'Number',T13,'Square Root',T29,'Square',T39,'Cube')
WRITE (10,120)
120 FORMAT (1X,T4,'======',T13,'===========',T29,'======',T39,'===='/)
! Generate the required values, and print them out.
DO i = 1, 10
square_root = SQRT ( REAL(i) )
square = i**2
cube = i**3
WRITE (10,130) i, square_root, square, cube
130 FORMAT (1X, T4, I4, T13, F10.6, T27, I6, T37, I6)
END DO
END PROGRAM table