# strverscmp

## NAME



           strverscmp - compare two version strings
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#define _GNU_SOURCE** /* See feature_test_macros(7) */
           **#include <string.h>**
    
           **int strverscmp(const char ***_s1_**, const char ***_s2_**);**
    


## DESCRIPTION



           For a dataset like _jan1_ , _jan2_ , ..., _jan9_ , _jan10_ , ...  sorting it
           lexicographically yields _jan1_ , _jan10_ , ..., _jan2_ , ..., _jan9_.  The
           task of **strverscmp**() is to compare two strings yielding the former
           order, while strcmp(3) finds only the lexicographic order.  This
           function does not use the locale category **LC_COLLATE** , so is meant
           mostly for situations where the strings are expected to be in
           ASCII.  This is different from the ordering produced by sort(1)
           **-V**.
    
           What this function does is the following.  If both strings are
           equal, return 0.  Otherwise, find the position between two bytes
           with the property that before it both strings are equal, while
           directly after it there is a difference.  Find the largest
           consecutive digit strings containing (or starting at, or ending
           at) this position.  If one or both of these is empty, then return
           what strcmp(3) would have returned (numerical ordering of byte
           values).  Otherwise, compare both digit strings numerically, where
           digit strings with one or more leading zeros are interpreted as if
           they have a decimal point in front (so that in particular digit
           strings with more leading zeros come before digit strings with
           fewer leading zeros).  Thus, the ordering is _000_ , _00_ , _01_ , _010_ , _09_ ,
           _0_ , _1_ , _9_ , _10_.
    


## RETURN VALUE



           The **strverscmp**() function returns an integer less than, equal to,
           or greater than zero if _s1_ is found, respectively, to be earlier
           than, equal to, or later than _s2_.
    


## ATTRIBUTES



           For an explanation of the terms used in this section, see
           attributes(7).
           ┌──────────────────────────────────────┬───────────────┬─────────┐
           │ **Interface** │ **Attribute** │ **Value** │
           ├──────────────────────────────────────┼───────────────┼─────────┤
           │ **strverscmp**()                         │ Thread safety │ MT-Safe │
           └──────────────────────────────────────┴───────────────┴─────────┘
    


## STANDARDS



           GNU.
    


## EXAMPLES



           The program below can be used to demonstrate the behavior of
           **strverscmp**().  It uses **strverscmp**() to compare the two strings
           given as its command-line arguments.  An example of its use is the
           following:
    
               $ **./a.out jan1 jan10** ;
               jan1 < jan10
    
       **Program source**
    
           #define _GNU_SOURCE
           #include <stdio.h>
           #include <stdlib.h>
           #include <string.h>
    
           int
           main(int argc, char *argv[])
           {
               int res;
    
               if (argc != 3) {
                   fprintf(stderr, "Usage: %s <string1> <string2>\n", argv[0]);
                   exit(EXIT_FAILURE);
               }
    
               res = strverscmp(argv[1], argv[2]);
    
               printf("%s %s %s\n", argv[1],
                      (res < 0) ? "<" : (res == 0) ? "==" : ">", argv[2]);
    
               exit(EXIT_SUCCESS);
           }
    


* * *