get string parts using strtok

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i have string like that

SQL

update std set name=test,phone=8787898 where id = 10

i want to split it into tokens using space and =, delmiters i'm using the follwoing code

the probleme is that i can not select where token the pointer at that stage is NULL
how to make it point to where

C++

pch=strtok(str," ");

while(pch !=NULL)
{

   if(strcmpi("update",pch)==0)// check update 
    {
       pch=strtok(NULL," ");
       if(strcmpi("std",pch)==0)
          {
            pch=strtok(NULL," ");
            if(strcmpi("set",pch)==0)
             {
               pch=strtok(NULL," ");//pointer(pch) holds name=test,phone=8787898
               pch= strtok(pch,"=,");//pointer holds name
               if(strcmpi("name",pch)==0)
                 {
                    pch=strtok(NULL,"=,");//pointer holds test
                    pch=strtok(NULL,"=,");//pointer holds phone
                  }
               if(strcmpi("phone",pch)==0)
                  {
                    pch=strtok(NULL,"=,");//pointer holds 8787898 
                    pch=strtok(NULL,"=,");//pointer holds NULL
                   }
                pch=strtok(NULL," ");//pointer holds NULL
                if(strcmpi("where",pch)==0)
                 {
                    printf("where selected");
                  }
              }
           }
    }
}

Posted 9-Nov-14 14:39pm

TheSniper105

Updated 9-Nov-14 14:49pm

Garth J Lancaster

v2

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2 solutions

Solution 1

quite frankly, I think strtok approach is a little simplistic for something like a sql statement

you'll see Ive put a code tag for sql around your statement - interesting, it highlights the sql keywords update, set, and where ... if I wanted a 'simpler' approach, I would 'split up the string into sections', each section being the update, set and where 'clauses', and then maybe strtok for the pieces (but that may still be too simplistic)

are you open to using any other tools, or do you have to do this the hard way ?

Posted 9-Nov-14 14:54pm

Garth J Lancaster

Comments

TheSniper105 9-Nov-14 21:29pm

other tools like what ??

Garth J Lancaster 9-Nov-14 21:43pm

ok apart from a hybrid method of what you started with, but using sscanf to get the positions of the keywords, you could take a look at http://www.hwaci.com/sw/lemon/ and have a look at the SQLite source code - they use their Lemon parser to parse SQLite's sql

TheSniper105 9-Nov-14 23:56pm

i prefer hard way as i' not actually run sql statments

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BacchusBeale · Accepted Answer · 2014-11-09T16:17:00

Solution 2

Hi,
I tried strtok with all delims listed and all tokens where separated into a list.

C#

void P(char *p)
{
    printf("%s\n", p);
}
int main()
{
    char str[]="update std set name=test,phone=8787898 where id = 10";
    char *pch=strtok(str," =,");
    P(pch);
    while(pch)
    {
        pch = strtok (NULL, " =,");
        if(pch != NULL)
          P(pch);
    }

    return 0;
}

Posted 9-Nov-14 16:17pm

BacchusBeale

Comments

TheSniper105 9-Nov-14 23:55pm

can you print them all ??

BacchusBeale 11-Nov-14 19:27pm

That's what the code does. strtok looks for any delim in the list " =," and returns next token on each call.