convtc.f

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      subroutine convtc (num,nchar, loc)                                
c
c  library subroutine                                                   
c                                                                       
c  module name: convtc                                                  
c                                                                       
c  version    : 1.0                                                     
c                                                                       
c  programmer : lucy liu and michael peng, stx, august 1990             
c                                                                       
c  purpose: to convert first nchar digits of an integer into a character
c           or a string. (note: nchar doesn't include the sign if num   
c           is negative)                                                
c                                                                       
c  calling sequence: convtc (num,nchar, loc)                            
c                                                                       
c  subroutines called: none                                             
c                                                                       
c  intrinsic functions used: char, ichar, iabs                          
c                                                                       
c  common blocks used: none                                             
c                                                                       
c  arguments and local variables:                                       
c                                                                       
c      name    type  i/o  descriptions                                  
c   ---------  ----  ---  ----------------------------------------------
c   num        i*4    i   integer number for conversion                 
c   nchar      i*4    i   number of chars to be converted               
c   loc        c*x    o   char variable or array (string)               
c   istart     i*4        start position of integral char string:       
c                         1 for positive integer; 2 for negative integer
c   irem       i*4        absolute value or remainder by 10             
c   itemp      i*4        temporary buffer                              
c***********************************************************************
c                                                                       
c --- arguments                                                         
c                                                                       
      integer   num, nchar                                              
      character loc(1)                                                  
c                                                                       
c --- local variables                                                   
c                                                                       
      integer   istart, irem, itemp                                     
c                                                                       
      irem = iabs(num )                                                
      istart = 1                                                        
c                                                                       
c --- keep the sign if the integer is negative                          
c                                                                       
      if (num.lt.0) then                                                
         nchar = nchar + 1                                              
         loc(1) = '-'                                                   
         istart = istart + 1                                            
      endif                                                             
c                                                                       
c --- convert digit by digit starting with the least significant digit  
c                                                                       
      do 100 i = nchar, istart, -1                                      
         itemp = irem / 10                                              
         loc(i) = char(irem - itemp * 10 + ichar('0'))                 
         irem = itemp                                                   
 100  continue                                                          
c                                                                       
c --- put an asterisk at the first position if the actual number of     
c --- digits in the integer is found greater than nchar                 
c                                                                       
      if (irem.ne.0) loc(1) = '*'                                       
c                                                                       
      return                                                            
      end                                                               
c***********************************************************************