Comparing strings from within strings

[Rick]

Hi,

I need to extract some data from a string being passed. I was wondering
what would be the best way of doing this. For example, I have two
strings: "SWITCH1CLOSE" and "GATE1OPEN"

I need to take out the SWITCH part of out of the string, the "1" and the
"close". Similarly, I need to take out GATE, 1 and open from the second
string. Should I use the "strstr" function for comparing the substrings
GATE, CLOSE, OPEN etc? I can't use the tokenizing function here so I'm
not sure what would be the best way of doing this. Any suggestions would
be great! Thanks


Rick

 

[Richard Heathfield]

Hi,

I need to extract some data from a string being passed. I was wondering
what would be the best way of doing this. For example, I have two
strings: "SWITCH1CLOSE" and "GATE1OPEN"

I need to take out the SWITCH part of out of the string, the "1" and the
"close". Similarly, I need to take out GATE, 1 and open from the second
string. Should I use the "strstr" function for comparing the substrings
GATE, CLOSE, OPEN etc? I can't use the tokenizing function here so I'm
not sure what would be the best way of doing this. Any suggestions would
be great! Thanks

Yes, strstr is fine. You might not want to search from the beginning each
time, though. For example, you might want to find "GATE" and "OPEN" in your
second example. You can use a pointer to keep track of how far "into" the
string you are, and strstr to compare from that point.

char s[] = "SOMERANDOMLEADINGTEXTGATE1OPEN";
char *p = strstr(s, "GATE");

if(p != NULL)
{
/* do whatever it was you needed to do at this point, then ... */
p += strlen("GATE"); /* skip past characters of "GATE", so p now points to
the '1' character. */
p = strstr(p, "OPEN"); /* off to the next match... */


If you want to jump forward to a particular /character/, you might also find
strchr useful.

 

[Rick]

Thanks a lot Richard! One question though, is there a Standard C
function that converts lower case characters to upper case? Thanks

Rick

 

[Irrwahn Grausewitz]

Thanks a lot Richard! One question though, is there a Standard C
function that converts lower case characters to upper case? Thanks

Lookup toupper in your library reference.

Regards