c中的char数组的分割错误

Question

please tell me why this code give me segmentation fault?
I want to split the command into tokens but I don't know why it give me segmentation fault!!

char command[500]="asdadas asdasdas asdadas";   
int i,j,k;
char tokens[4][200];

for(i=0,j=0,k=0;  i<strlen(command);  i++)
{
    if(command[i]==' ') 
    {
        tokens[j][k]='\0';
        k=0;
        j++;
        continue;
    }

    tokens[j][k]=command[i];
    k++;
}
tokens[j][k]='\0';

Answer 1

command is uninitialised. That means that the strlen(command) call might run beyond the 500 bytes, causing a segmentation fault.

Initialise your command array before using it. For example with memset .

Other than that, there is no bounds checking whatsoever and some arbitrary array lengths. This is bound to fail.

Answer 2

You have a problem with tokens . You are incrementing j and k in each iteration without any check.

Anyway, dou you know there already exists functions that do what you wanna do?

Answer 3

To add More into other folks answer, you can use strsep. Look at the following sample code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int main ()
{
char * command=NULL, *tok=NULL;

command =strdup("asdadas asdasdas asdadas");
while ((tok = strsep(&command, " ")) != NULL )
{
  printf ("..%s..\n", tok);
}

Hope it helps. ;)