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C Library Functions  - s2v (3)

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NAME

s2v(3f) - [M_strings:TYPE] function returns doubleprecision numeric value from a string (LICENSE:PD)

CONTENTS

Synopsis
Description
Options
Returns
Example
Author
License

SYNOPSIS

function s2v(string[,ierr][,onerr])

    character(len=*)             :: string
    doubleprecision              :: s2v
    integer,intent(out),optional :: ierr
    class(*),intent(in),optional :: onerr

DESCRIPTION

This function converts a string to a DOUBLEPRECISION numeric value.

The intrinsics INT(3f), REAL(3f), and DBLE(3f) are also extended to take CHARACTER variables. The KIND= keyword is not supported on the extensions.

OPTIONS

string	holds string assumed to represent a numeric value
ierr	If an error occurs the program is stopped if the optional parameter IERR is not present. If IERR returns a non-zero value an error occurred.
onerr	The value to return on error. A value of NaN is returned on error by default.

RETURNS

s2v	numeric value read from string

EXAMPLE

Sample Program:

   program demo_s2v

    use M_strings, only: s2v, int, real, dble
    implicit none
    character(len=8)              :: s=’ 10.345 ’
    integer                       :: i
    character(len=14),allocatable :: strings(:)
    doubleprecision               :: dv
    integer                       :: errnum

    ! different strings representing INTEGER, REAL, and DOUBLEPRECISION
    strings=[&
    &’ 10.345       ’,&
    &’+10           ’,&
    &’    -3        ’,&
    &’    -4.94e-2  ’,&
    &’0.1           ’,&
    &’12345.678910d0’,&
    &’              ’,& ! Note: will return zero without an error message
    &’1 2 1 2 1 . 0 ’,& ! Note: spaces will be ignored
    &’WHAT?         ’]  ! Note: error messages will appear, zero returned

    ! a numeric value is returned,
    ! so it can be used in numeric expression
    write(*,*) ’1/2 value of string is ’,s2v(s)/2.0d0
    write(*,*)
    write(*,*)’ STRING            VALUE                    ERROR_NUMBER’
    do i=1,size(strings)
       ! Note: not a good idea to use s2v(3f) in a WRITE(3f) statement,
       ! as it does I/O when errors occur, so called on a separate line
       dv=s2v(strings(i),errnum)
       write(*,*) strings(i)//’=’,dv,errnum
    enddo
    write(*,*)"Extended intrinsics"
    write(*,*)’given inputs:’,s,strings(:8)
    write(*,*)’INT(3f):’,int(s),int(strings(:8))
    write(*,*)’REAL(3f):’,real(s),real(strings(:8))
    write(*,*)’DBLE(3f):’,dble(s),dble(strings(:8))
    write(*,*)"That’s all folks!"

    end program demo_s2v

   Expected output

    >1/2 value of string is    5.1725000000000003
    >
    > STRING            VALUE                    ERROR_NUMBER
    > 10.345       =   10.345000000000001                0
    >+10           =   10.000000000000000                0
    >    -3        =  -3.0000000000000000                0
    >    -4.94e-2  =  -4.9399999999999999E-002           0
    >0.1           =  0.10000000000000001                0
    >12345.678910d0=   12345.678910000001                0
    >              =   0.0000000000000000                0
    >1 2 1 2 1 . 0 =   12121.000000000000                0
    >*a2d* - cannot produce number from string [WHAT?]
    >*a2d* - [Bad value during floating point read]
    >WHAT?         =   0.0000000000000000             5010
    >Extended intrinsics
    >given inputs: 10.345 10.345 +10 -3 -4.94e-2 0.1
    12345.678910d0 1 2 1 2 1 . 0
    >INT(3f): 10 10 10 -3 0 0 12345 0 12121
    >REAL(3f): 10.3450003 10.3450003 10.0000000 -3.00000000
    -4.94000018E-02
    >          0.100000001 12345.6787 0.00000000 12121.0000
    >DBLE(3f): 10.345000000000001 10.345000000000001
    10.000000000000000
    >          -3.0000000000000000 -4.9399999999999999E-002
    0.10000000000000001
    >          12345.678910000001 0.0000000000000000
    12121.000000000000
    >That’s all folks!

AUTHOR

John S. Urban

LICENSE

Public Domain

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Nemo Release 3.1

s2v (3)

July 22, 2023

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