sscanf string parsing
I am trying to parse data from a string. I know that the first thing that I want from the string is a string as well, but I want to limit the number of characters extracted from the string. Here's what I tried but it doesn't work - what am I doing wrong or what's the correct way or best way to handle this:
<code>
if (sscanf(somestring,"%*s%d",STRINGSIZE,tostr,&toint )==2)
</code>
Hi,
Below is a sample that puts the first four char's form one string into another string.
#include <stdio.h>
#include <conio.h>
int main()
{
char *mystr = "this is the input string";
char frstfour[5];
int x;
frstfour[4] = 0; // string terminator
for(x = 0; x < 4;++x)
{
frstfour[x] = mystr[x];
}
printf("\n%s\n",frstfour);
getch();
return 0;
}
Maybe you can get some ideas from it.
lol
Pappy
You learn something new everyday.
Assuming your string is something harder like STR10, you can easily do it like this
If there's some delimiting character between the string and the number then it's way easier :-)Code:#include <stdio.h> #include <string.h> #include <stdlib.h> int main(void) { int toint; char tostr[4] = {0}; char *src = "STR10", *pos = src; strncpy(tostr, pos, 3); toint = atoi(pos + 3); printf("The string is %s\nThe number is %d\n", tostr, toint); return 0; }
>>if (sscanf(somestring,"%*s%d",STRINGSIZE,tostr,&toint )==2)Code:#include <stdio.h> int main(void) { int toint; char tostr[4] = {0}; char *src = "STR 10"; if (sscanf(src, "%s %d", tostr, &toint) == 2) { printf("The string is %s\nThe number is %d\n", tostr, toint); } return 0; }
For the scanf family, the * modifier means to read and discard that item, so your call reads everything up to whitespace or the end of the string and just throws it away. That's a problem with scanf and printf, their modifiers don't match and that causes confusion :-)
*Cela*
Would the following limit my input string to 10 characters?:
Code:#include <stdio.h> int main(void) { /* ABCDEFGHIJKL is > 10 chars long and then a number follows */ char *input_str="ABCDEFGHIJKL 123"; char tostr[11]; int num; if(sscanf(input_str,"%10s%d",tostr,&num)==2) { printf("String limited to 10 = %s\n",tostr); printf("Number = %d\n",num); } }
>>Would the following limit my input string to 10 characters?
Yes, but sscanf would fail because there are more than 10 non-numeric characters, after reading 10 there would still be some for the next item to choke on :-)
*Cela*
That's what I needed to know. I'm disappointed though that I have to hard code in the 10 to limit the string size instead of being able to use the * and a constant to perform the limiting. But I do want the sscanf to fail for any string larger than 10 characters.
