sscanf with "_" delimiter in C

Question

I'm running the following code in C. I'm not getting the right answer.

int main()
{

    char test[100] = "This_Is_A_Test_99";
    char tmp1[10],tmp2[10],tmp3[10],tmp4[10],tmp5[10];

    sscanf(test,"%[^'_'],%[^'_'],%[^'_'],%[^'_'],%s",tmp1,tmp2,tmp3,tmp4,tmp5);

    printf ("Temp 1 is %s\n",tmp1);
    printf ("Temp 2 is %s\n",tmp2);
    printf ("Temp 3 is %s\n",tmp3);
    printf ("Temp 4 is %s\n",tmp4);
    printf ("Temp 5 is %s\n",tmp5);

    return 0;
}

The output I get is

Temp 1 is This
Temp 2 is 
Temp 3 is 
Temp 4 is 
Temp 5 is 

What is that I have to do fetch "This" "Is" "A" "Test" and "99" on individual variables.

Answer 1

sscanf(test,"%[^'_'],%[^'_'],%[^'_'],%[^'_'],%s",tmp1,tmp2,tmp3,tmp4,tmp5);

should be

sscanf(test,"%[^_]_%[^_]_%[^_]_%[^_]_%s",tmp1,tmp2,tmp3,tmp4,tmp5);

Note that you are separating the placeholders with , instead of _.

See http://ideone.com/8zBmG.

Also, you don't need the 's unless you want to skip the single quotes as well.

(BTW, you should take a look into strtok_r.)

Answer 2

You are scanning commata between your strings, and there are none in the text. Remove them from the pattern:

sscanf(test,"%[^'_']%[^'_']%[^'_']%[^'_']%s",tmp1,tmp2,tmp3,tmp4,tmp5);

Apostrophes are probably unnecessary, too. You don't need to quote anything since no shell is going to expand it:

sscanf(test,"%[^_]%[^_]%[^_]%[^_]%s",tmp1,tmp2,tmp3,tmp4,tmp5);

Taking up pmg's suggestion, you should write the length of your temporary explicitly into the scanf arguments to make sure you don't get buffer overflows:

sscanf(test,"%9[^_]%9[^_]%9[^_]%9[^_]%9s",tmp1,tmp2,tmp3,tmp4,tmp5);

And then check the return value:

int token_count = sscanf(test,"%9[^_]%9[^_]%9[^_]%9[^_]%9s",tmp1,tmp2,tmp3,tmp4,tmp5);
if ( token_count != 5 ) { fprintf(stderr, "Something went wrong\n"); exit(42); }

Answer 3

It looks to me like you have included commas (,) in your sscanf string.

But there are no commas in your input. Without any commas to process, sscanf is failing after the first string "This"

I recommend trying the format string:

"%[^_]_%[^_]_%[^_]_%[^_]_%s"