String partitioning function and its implementation method in C language _c language

1. Introduction of the problem

When I wrote a simulated execution instruction under Linux, I encountered the input "cat a.c", To break the string down into two separate strings for cat and A.C, although I know there is a strtok, but I want to try to write, so I wrote one, but always encountered such or such a problem, although the final adjustment, but indeed wasted a lot of time; later, after handing in the homework and carefully read the Strtok function, found The original Linux has been changed to STRSEP, all here to write the process of their walk.

2, write their own string segmentation function: For segmentation instructions, such as Cat A.C will eventually be divided into cat and a.c two strings, MV A.C B.C will eventually be divided into MV and A.C and B.C three strings.

Specifically implemented as follows:

#include <stdio.h> #include <string.h> #define Max_len 128 void Main () {int i,length,ct=0,start =-1;
  Char Inputbuffer[max_len],*args[max_len];
  strcpy (InputBuffer, "MV A.C B.C");
   Length=strlen (InputBuffer); for (i = 0; I <= length; i++) {switch (Inputbuffer[i]) {case ": Case ' t ':/* Argument separator  S */if (start!=-1) {ARGS[CT] = &inputBuffer[start];
      /* Set up pointer * * ct++; } Inputbuffer[i] = '; /* Add a null char;
      Make a C String */start =-1;
    Break Case ' I ':/* should be the final char examined */if (start!=-1) {ARGS[CT] = &inputbuffer[sta
        RT];
      ct++;
      } Inputbuffer[i] = '; ARGS[CT] = NULL;
    * No more arguments to the this command * * break;
    Default:/* Some other character */if (start = = 1) start = i;
  printf ("The string after decomposition is: \ n"); for (i=0;i<ct;i++) printf ("%s \ n", Args[i]); }

3, the job submitted and query the Strtok, found that the use of strtok function will be more convenient

The specific examples are as follows:

#include <stdio.h>
#include <string.h>
int main ()
{
  char str[] = "mv a.c B.C";
  char *p; 
  p = strtok (str, "");
  while (p)
  {  
    printf ("%s\n", p);  
    p = strtok (NULL, "");  
  }
  return 0;
}

4, in the later version of Linux2.6.29, Strtok was replaced by STRSEP.

The specific examples are as follows:

#include <stdio.h>
#include <string.h>
int main ()
{
  char str[] = "mv a.c B.C";
  char *p;
  char *buff;
  Buff=str;
  p = strsep (&buff, "");
  while (p)
  {
    printf ("%s\n", p);
    p = strsep (&buff, "");
  }
  return 0;
}

And in the Linux codeblog of my own computer, the code in run 4 requires 0.029s, and the code running 3 requires 0.044s, which means that strsep speed is indeed faster than strtok.

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