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: http://www.stsci.edu/~sontag/spicedocs/cspice/lx4num_c.html
Дата изменения: Sat Dec 17 06:09:17 2005 Дата индексирования: Mon Apr 11 00:05:03 2016 Кодировка: Поисковые слова: п п п п п |
Scan a string from a specified starting position for the end of a number.
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VARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- string I Any character string. first I First character to scan from in string. last O Last character that is part of a number. nchar O Number of characters in the number.
string is any character string. first is the location in the string to beginning scanning for a number. It is assumed that the number begins at first. The normal range of first is 0 : strlen(string)-1.
last is the last character at or after first such that the substring ranging from string[first] through string[last] is a number. If there is no such substring, last will be returned with the value first-1. If a number is found, last will be in the range is 0 : strlen(string)-1. nchar is the number of characters in the number that begins at index first and ends at last. If there is no such string nchar will be given the value 0.
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This routine allows you to scan forward in a string to locate a number that begins on the input character first. Note that all decimal numbers are included in the list of numbers. The main difference between decimal numbers and numbers is that numbers may have an exponential expression attached (i.e. the exponent character 'e','E','d' or 'D' followed by an signed integer).
1) Suppose you believe that a string has the form X%Y%Z where X, Y, and Z are numbers of some unknown length and % stands for any character that cannot occur in a number. You could use this routine to locate the numbers in the string as shown below. We'll keep track of the beginning and ending of the numbers in the integer arrays b and e. #include <string.h> #include "SpiceUsr.h" . . . first = 0; i = 0; len = strlen(string); while ( first < len-1 ) { lx4num_c ( string, first, &last, &nchar ); if ( nchar > 0 ) { i++; b[i] = first; e[i] = last; first = last + 2; } else { first++; } }
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1) If first is beyond either end of the string, then last will be returned with the value first-1 and nchar will be returned with the value 0. 2) If string[first] is not part of a number then last will be returned with the value first-1 and nchar will be returned with the value 0. 3) If the input string pointer is null, the error SPICE(NULLPOINTER) will be signaled. 4) If the input string has length zero, last will be set to first-1 and nchar will be set to zero. This case is not considered an error.
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N.J. Bachman (JPL) W.L. Taber (JPL)
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-CSPICE Version 1.0.0, 18-AUG-2002 (NJB) (WLT)
Scan a string for a number.