Ok so I've got a kind of weird question
I need to take output such as:
"12 Spiderman message goes here\n
13 Superman message goes here"
And reformat it like
12: Spiderman - message goes here
13: Superman - message goes here
I tried using strtok but it ended up just being a mess. The whole problem with doing that is these statements (there could be anywhere from 1 - infinity lines) are all connected into one char array. I need an easier way to insert chars into these statements.
sscanf + sprintf
sscanf for %d, %s, %[^\n]
sprintf %d space %s space %s
Give it a shot and post your attempt / what you're stuck on specifically.
Quzah.
Hope is the first step on the road to disappointment.
That makes sense, but what exactly is the %[^\n] doing?Originally Posted by quzah
Here's what I just tried, but its giving me a segmentation fault. i have a feeling it might have to do with my misunderstanding of what %[^\n] is doing
(response is the string)
char str [100];
char str2 [100];
char strfinal[MAX_RESPONSE];
int i;
sscanf(response, "%d %s %[^\n]",i, str, str2);
sprintf(strfinal, "%d: %s - %s", i, str, str2);
printf("%s\n", strfinal);
First, check the forum faqs for the use of code tags, it makes code a lot easier to read.
Where is response defined?
It's probably segfaulting because response is either undefined or too small.
Ok I will check it out and that's not the case. Response is defined in the rest of my code. I've tested it to make sure response is ok. I can print off response fine with no segmentation error and it contains the string I posted in my initial comment.
It may be in the rest of the code, but is it in a scope where the listed functions can see it?
For example if you defined it inside main() it's possible with a function call outside of main, it isn't valid at that point in the program.
Can you post your whole program... might make things easier, if it's not too long.
It's stripping line feeds. If there is no chance of a trailing line feed you could try replacing that with %s which would read a second string.
No, it definitely is valid right there. It's defined just before this segment of code all in the very same method. I'm 99% sure the problem is in something I wrote out 2 posts ago. I just don't know what. And I still am not sure what %[^\n] is doing.
Last edited by rkrajnov; 12-04-2010 at 11:14 PM.
What do you mean by stripping line feeds.... there definitely is a trailing line feed. Take a look at my initial post and you can see what the input is (note it could be 3, 4, 5+ lines as well).
Post a complete small version of your program. Not some huge crap we have to read through, but a small illustration of the issue. Go read the format specifier sections for scanf/printf to better understand what it's doing. (here)
Quzah.
Hope is the first step on the road to disappointment.
Ok... there are linefeeds in the file... but are they stripped when you load it into the string?
Quzah is right... we need to see your code before we can do much more...
Here's the main relevant method. It gets a string response through a program given to us. The sendCommand method outputs into response (so response has right output no questions asked). Then I removed the '\r' (not really important) and alter the "response". That works fine and is irrelevant to my question pretty much.
messages is printed down here after initial call of get_messages and then through every loop: (messages is global variable)Code:void get_messages() { char response[ MAX_RESPONSE ] = ""; char lastNum[10]; sprintf(lastNum, "%d", lastMessage); sendCommand(host, port, "GET-MESSAGES", user, password, lastNum, response); char *temp; int x = 0; temp = response; //removes /r while(x < strlen(response)-2) { if (response[x] != '\r') *temp++ = response[x]; if (response[x] == '\r') lastMessage++; x++; } *temp = 0; char str [100]; char str2 [100]; char strfinal[MAX_RESPONSE]= ""; int i; messages = malloc(MAX_RESPONSE * sizeof(char)); if(strcmp(response, "NO-NEW-MESSAGES") != 0){ sscanf(response, "%d %s %[^\n]",i, str, str2); sprintf(messages, "%d: %s - %s", i, str, str2); } else{ messages = ""; } }
Now If I replace the sscanf and sprintf with messages = strdup(response), messages prints perfectly. keep that in mind.Code:void * getMessagesThread(void * arg) { // This code will be executed simultaneously with main() // Get messages to get last message number. Discard the initial Messages char response[ MAX_RESPONSE ] = ""; get_messages(); //the method posted above while (1) { // Get messages after last message number received. get_messages(); // Print messages printf("%s", messages); // Sleep for ten seconds usleep(2*1000*1000); } }
Last edited by rkrajnov; 12-04-2010 at 11:37 PM.
Ok, that answered my question... response does not have carriage returns in it.
Try it like this...
Code:if(strcmp(response, "NO-NEW-MESSAGES") != 0){ sscanf(response, "%d %s %s",i, str, str2); sprintf(messages, "%d: %s - %s", i, str, str2);
unfortunately I tried that and it results in a segmentation fault as well.
