strings

This is a discussion on strings within the C Programming forums, part of the General Programming Boards category; How can I extract a specific string from a string? The string comes over a serial port in the form ...

  1. #1
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    Question strings

    How can I extract a specific string from a string?

    The string comes over a serial port in the form of "@15:28:08D ". It just so happens that this string is the time of day with a character on the beginning and at the end.

    I need to extract the hours, minutes, and seconds only.

    I would certainly appreciate any and all help!

  2. #2
    Registered User The Dog's Avatar
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    Without using library functions, you could just use this.

    char date[MAX];
    char temp[MAX];

    int i , j;

    for( i=1, j=0; date[i] != '\o'; i++, j++)
    {
    temp[j] = date[i];
    }

    temp[j-1] = '\o';

  3. #3
    Registered User JoshG's Avatar
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    If it is always in the format of "@15:28:08D"

    Then maybe you could;

    char hour[2];
    hour[0] = date[1];
    hour[1] = date[2];

    int thehour = atoi(hour);

    I think that would work, I don't really know though. If it does you could do the same thing to get the minutes and the seconds.

  4. #4
    ATH0 quzah's Avatar
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    sscanf is like scanf, or fscanf, but it scans another string as the source.
    strstr will locate a given string in another string.

    These are just a few options.

    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
    End Of Line Hammer's Avatar
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    Or you could do this.....
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main(void)
    {
    	char mystring[] = "@15:28:08D";
    	
    	printf ("string is %s\n", mystring);
    	memmove(mystring, mystring+1, 8);
    	mystring[8] = '\0';
    	printf ("string is now %s\n", mystring);
    	return(0);
    }
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  6. #6
    ATH0 quzah's Avatar
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    > Or you could do this.....

    Well hell, if you're going to be that way about it!

    printf("%s", string + 1 );


    Quzah.
    Hope is the first step on the road to disappointment.

  7. #7
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    Question

    The problem is that the string I'm looking for (time of day, HH:MIN:SEC) is updating constantly and therefore is a dynamic string. How do I find a dynamic string on a line and then how can I get it into the variable I want it to go to?

    A second question I forgot to add previously. How can I find another string on a line that is not always at the same location in the line? This string isn't always the same, it can be one of 158 possibilities. It is always 5 or 6 characters long and always has an underscore as it's third character. I would greatly appreciate any help!
    Thanks!

  8. #8
    ATH0 quzah's Avatar
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    Originally posted by Unregistered
    The problem is that the string I'm looking for (time of day, HH:MIN:SEC) is updating constantly and therefore is a dynamic string. How do I find a dynamic string on a line and then how can I get it into the variable I want it to go to?

    A second question I forgot to add previously. How can I find another string on a line that is not always at the same location in the line? This string isn't always the same, it can be one of 158 possibilities. It is always 5 or 6 characters long and always has an underscore as it's third character. I would greatly appreciate any help!
    Thanks!
    Meaning what exactly? How is it a "dynamic string"? You must have some pointer to this string. If so, what's the problem? If not, then your question really is "how do I read from ___?"

    If you have a file stream, which is what you use to read from specific devices, then just use fread or something similar.

    For your second question, as I've already stated, use sscanf.

    Quzah.
    Hope is the first step on the road to disappointment.

  9. #9
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    quzah,
    Maybe dynamic was an improper description. What I need to do is take this string "@HH:MM:SSD" and extract the HH, MM, and SS separately and put each respective one into a variable. Can you or somebody else show me how this can be done?
    Thanks!

  10. #10
    ATH0 quzah's Avatar
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    Did you even look at sscanf, because I really think that sscanf will do the trick. Once again, might I suggest sscanf? I find sscanf to be a handy tool for this sort of thing. Perhaps you should consider sscanf. sscanf is quite useful in this situation. This is one of those times when sscanf would help out.

    And finally...

    sscanf should do the job nicely.

    Get the message?

    Quzah.
    Hope is the first step on the road to disappointment.

  11. #11
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    sscannnnf. I tried it but it blows up!

  12. #12
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    Code:
    #include <string.h>
    #include <stdio.h>
    
    int main(){
        char string[] = "@15:28:08D";
        int hour, minute, second;
        sscanf(string,"%*c%d:%d:%d%*c",&hour,&minute,&second);
        printf("%d\n%d\n%d\n",hour, minute, second);
        return 0;
    }
    Enough said.

    kwigibo

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