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CHAPTER 5

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

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CHAPTER 5

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  1. CHAPTER 5 INPUT/OUT FORMAT

  2. 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

  3. 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 right-justified. In reading the numbers anywhere within the field length are read

  4. 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.

  5. 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.

  6. 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***********

  7. 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 • **************************************************************

  8. 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

  9. Other Descriptors • X = for space • T = for position • / = for new line

  10. 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 1010 FORMAT (' ','Line ', I6, ': Value = ',F10.4 ) END DO readloop CLOSE ( UNIT=3 )

  11. 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)

  12. 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

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