specifying variable field width in sscanf

Question

I have the following sscanf statement:

sscanf(line, "%*s %511s %511s",protocol,hexdata)

Now line consists of the following form " a b c ". It's clear I am ignoring the value a by giving %*s. I take the values of b and c into protocol and data.

What I would like to do is I dont want to hardcode 511. I am just unable to do so. I tried the following but it does not seem to work.

    sprintf(log_buffer,"1234 56789");
    printf("\n Buffer is : %s \n",log_buffer);

    strcpy(format,"%*s ");                    // gives %*s
    sprintf(format1, "%%%ds", 5);            // gives %5s
    printf("\n Format is : %s ",format);
    printf("\n Format1 is : %s ",format1);
    strcat(format,format1);
    printf("\n new format is : %s ",format);

    sscanf(log_buffer,format,name);

    printf(" Name is : %s ",name);
    printf(" \n Size of name %d ",strlen(name));

This gives me junk value.

Sample output:

Buffer is : 1234 56789
Format is : %*s
Format1 is : %5s
new format is : %*s %5s
Name is : �
8r�2�%*s %5s  
Size of name 15

What is wrong here ? I just have to prevent hardcoding variable field.

Answer 1

my declarations are as follows char format[5]={0};

The format string can hold 4 chracters and the zero terminator. That is not enough for "%*s %5s"!

Increase the array size.