CHAR and ICHAR functions

[andrea213]

Hello,

I am trying to convert a high number (e.g. 123456789) into a character and then reconvert that character into the first number in another file.
To do this, I am using CHAR and ICHAR functions.
Using:

[tt] WRITE(*,*) ICHAR(CHAR(123456789,4),4) [/tt]

I get the number 123456789

However, when I try to separate the steps

[tt]
CHARACTER*1 TMPC1
INTEGER*4 TMPI1
INTEGER*4 NUMBER

NUMBER = 123456789

TMPC1 = CHAR (NUMBER,4)
TMPI1 = ICHAR (TMPC1,4)

WRITE(*,*) TMPI1 [/tt]

The ICHAR function only allows a character input of length 1 !!
I get the number 21. At first this was a bit confusing. It became clear when I used this program to convert the numbers 0, 1, 2, 3, ..., 300
The conversion was flawless until number 254, and then reseted:

253 > 253
254 > 254
255 > 255
256 > 0
257 > 1

This is due to the limited number of ASCII characters, which is 255.
Any thoughts on how to convert a number larger than 255, and retrieve the same number?

Many thanks!

 

[xwb]

Which compiler are you using? I've never seen ICHAR(number, kind) before.

 

[xwb]

What are you actually trying to achieve. Are you trying to convert a number into character form and then retrieve it from character form and convert it back to a number?

 

[andrea213]

I am using the gfortran compiler.

xwb (Programmer)
What are you actually trying to achieve. Are you trying to convert a number into character form and then retrieve it from character form and convert it back to a number?

That's exactly what I am trying to do here.

 

[FJacq]

The right way is to use READ and WRITE instead of ICHAR and CHAR.

Indeed, ICHAR/CHAR manage only bytes (1 byte = 8 bits = integer from 0 to 255 = a single character)

program test
  integer :: i,j
  character(9) :: c
  i=123456789
  write(c,'(i0)') i ! initializing the string c
  print*,c
  read(c,*) j ! reading back the integer from the string
  print*,j
end program

Result :

123456789
123456789


François Jacq