src/snark/getnum.cpp

   1 /*
   2  ***********************************************************
   3  $SNARK_Header: S N A R K  1 4 - A PICTURE RECONSTRUCTION PROGRAM $
   4  $HeadURL: svn://dig.cs.gc.cuny.edu/snark/trunk/src/snark/getnum.cpp $
   5  $LastChangedRevision: 80 $
   6  $Date: 2014-07-01 21:01:54 -0400 (Tue, 01 Jul 2014) $
   7  $Author: agulati $
   8  ***********************************************************
   9
  10  GETNUM SCANS THE INPUT AREA FOR THE NEXT NUMBER AND RETURNS
  11  THE INTERNAL FLOATING POINT REPRESENTATION OF THE NUMBER.
  12  IF THE INPUT AREA DOES NOT CONTAIN A NUMBER, ZERO IS
  13  RETURNED AND EOL IS SET TO .TRUE.
  14  */
  15
  16 #include <cstdlib>
  17 #include <cstdio>
  18 #include <cmath>
  19 #include <cctype>
  20
  21 #include "blkdta.h"
  22 #include "uiod.h"
  23 #include "chtoin.h"
  24
  25 #include "inputfile.h"
  26
  27 REAL InputFile_class::getnum(BOOLEAN NewLine, BOOLEAN* eol)
  28 {
  29         CHAR nextch;
  30         REAL mainval = 0, mainsign = 1;
  31         REAL expval = 0, expsign = 1;
  32         REAL numdigitsafterdot = 0;
  33
  34         *eol = FALSE;
  35         if (NewLine)
  36                 getnxt(FALSE);
  37
  38         // FIND START OF NUMBER (FIRST DIGIT OR DECIMAL POINT) AND SIGN
  39
  40         while (true)
  41         {
  42                 ptr++;
  43                 nextch = data[ptr];
  44                 if (ptr > DATASIZ)     // bug 190 - swr - 12/09/05
  45                 {
  46                         *eol = TRUE;
  47                         return 0.0;
  48                 }
  49                 if (isdigit(nextch))
  50                         break;
  51                 if (nextch == '.')
  52                         break;
  53                 if (nextch == '-')
  54                         mainsign = -1;
  55                 else
  56                         mainsign = 1;
  57         }
  58
  59         if (isdigit(nextch))
  60         {
  61                 while (isdigit(nextch))
  62                 {
  63                         mainval = mainval * 10.0 + chtoin(nextch);
  64                         ptr++;
  65                         nextch = data[ptr];
  66                 }
  67                 if (nextch == '.')
  68                 {
  69                         ptr++;
  70                         nextch = data[ptr];
  71                         while (isdigit(nextch))
  72                         {
  73                                 // try to parse (digit*)
  74                                 mainval = mainval * 10 + chtoin(nextch);
  75                                 numdigitsafterdot += 1;  // number of digits after '.'
  76                                 ptr++;
  77                                 nextch = data[ptr];
  78                         }
  79                 } // --period read after digit
  80         } // --digit read before (if at all) period
  81         else
  82         {
  83                 if (nextch == '.')
  84                 {
  85                         // parse (.digit+)
  86                         ptr++;
  87                         nextch = data[ptr];
  88                         if (!isdigit(nextch))
  89                         {
  90                                 // need a digit there
  91                                 fprintf(output,
  92                                                 "\n **** illegal floating point modifier encountered\n **** program aborted\n");
  93                                 exit(-1);
  94                         }
  95                         while (isdigit(nextch))
  96                         {
  97                                 mainval = mainval * 10 + chtoin(nextch);
  98                                 numdigitsafterdot += 1;  // number of digits after '.'
  99                                 ptr++;
 100                                 nextch = data[ptr];
 101                         }
 102                 } // --period read before any digit
 103                 else
 104                 {
 105                         // {digit+[.digit*],.digit+} not found
 106                         fprintf(output,
 107                                         "\n **** illegal floating point modifier encountered\n **** program aborted\n");
 108                         exit(-1);
 109                 }
 110         }
 111
 112         if ((nextch == 'e') || (nextch == 'E'))
 113         {
 114                 // try to parse ([+,-]digit[digit])
 115                 ptr++;
 116                 nextch = data[ptr];
 117                 if (nextch == '-')
 118                 {
 119                         expsign = -1;
 120                         ptr++;
 121                         nextch = data[ptr];
 122                 }
 123                 else
 124                 {
 125                         if (nextch == '+')
 126                         {
 127                                 ptr++;
 128                                 nextch = data[ptr];
 129                         }
 130                 }
 131                 if (!isdigit(nextch))
 132                 {
 133                         fprintf(output,
 134                                         "\n **** illegal floating point modifier encountered\n **** program aborted\n");
 135                         exit(-1);
 136                 }
 137                 else
 138                 {
 139                         expval = chtoin(nextch);
 140                         ptr++;
 141                         nextch = data[ptr];
 142                 }
 143                 if (isdigit(nextch))
 144                 {
 145                         // second possible digit
 146                         expval = expval * 10 + chtoin(nextch);
 147                         ptr++;
 148                         nextch = data[ptr];
 149                 }
 150         }
 151
 152         if (!isspace(nextch))
 153         {
 154                 // there is junk at the end
 155                 fprintf(output,
 156                                 "\n **** illegal floating point modifier encountered\n **** program aborted\n");
 157                 exit(-1);
 158         }
 159
 160         return mainsign * mainval * pow(10, (expsign * expval - numdigitsafterdot));
 161 }