Thread: Equivelant to Left or Right function of VB?

  1. #1
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    Question Equivelant to Left or Right function of VB?

    I need to get the 3 letters right of a string, the extension. Is there a function in string.h that can do that??
    I used Right and Left in Visual Basic.
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  2. #2
    End Of Line Hammer's Avatar
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    I don't believe there's a standard one, but it'd be easy enough to build one yourself.......
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  3. #3
    Im back! shaik786's Avatar
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    No (In ANSI C atleast). But you can write your own with very little ease using the standard string functions.

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    Has anyone made something similar? I dont want the actual code, but which functions did you use to make it?
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  5. #5
    Im back! shaik786's Avatar
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    >Has anyone made something similar? I dont want the actual code, but which functions did you use to make it?
    It depends on the way you implement it. strlen() is one which is real helpful.
    One way of implementing is, extract all the characters individually from the string in the range: [strlen(string) - 4] to [strlen(string)]

  6. #6
    End Of Line Hammer's Avatar
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    Just remember to account for strings that don't have enough characters (ie empty ones)........
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  7. #7
    and the hat of int overfl Salem's Avatar
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    Well if you start with

    char filename[] = "wibble.txt";

    Then you can locate the dot with

    char *p = strchr( filename, '.' );

    Or locate the .txt with

    char *p = strstr( filename, ".txt" );

    In both cases, p either points to the dot, or p is NULL indicating that nothing was found.

  8. #8
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    Oh thank you Salem, it worked strchr was the solution i needed!
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  9. #9
    ATH0 quzah's Avatar
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    Unless you're using DOS (or potentially some other OS), you don't know for sure that there is only one "." in the file name.

    Example: In *nix, it's common to have:

    ".tar.gz" on the end of the file.

    One way is simply to loop through the string from the end. (Basicly strchr does the same thing, just from the beginning.)
    Code:
    for( x = strlen( s ) -1; x > -1; x-- )
    {
        if( s[x] == charToFind ) break;
    }
    Now, you could use strchr. Just use it with more than one character. Or, even better, use it in a loop:

    Code:
    c = strchr( string, tofind );
    for( temp = c; temp != NULL; temp = strchr( c, tofind ) )
        if( temp != NULL ) c = temp;
    That should do it.

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

  10. #10
    End Of Line Hammer's Avatar
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    Correct me if I'm wrong, but wouldn't it be simpler to use strrchr().
    For example:
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main(void)
    {
    	char x[] = "filename.txt";
    	char *p;
    	
    	if ((p = strrchr(x, '.')) == NULL)
    		printf ("No extension\n");
    	else
    		printf ("Extension is %s\n", p+1);
    	
    	return 0;
    }
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  11. #11
    ATH0 quzah's Avatar
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    Sure. That'd work. However, are either of those two functions in the standard? My reference may be outdated, but it doesn't liste them as ANSI functions... (While it may be no big deal to the original poster, I'm generally pick regarding this.)

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

  12. #12
    and the hat of int overfl Salem's Avatar
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    Yes they are ANSI functions

  13. #13
    ATH0 quzah's Avatar
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    Originally posted by Salem
    Yes they are ANSI functions
    I need updated man pages then...

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

  14. #14
    End Of Line Hammer's Avatar
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    Originally posted by quzah
    Sure. That'd work. However, are either of those two functions in the standard? My reference may be outdated, but it doesn't liste them as ANSI functions...
    What 2 functions? I only used strrchr() and printf()? !! (I'm just being sarcastic, I guess you meant strchr() )

    Also, if your documentation doesn't liste them, it's probable that you have Ye Olde English version... I definately recommend updating.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  15. #15
    ATH0 quzah's Avatar
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    I just use the man pages while at work for quick reference. Some one needs to update them. (They don't list strchr and strrchr as conforming to ANSI.) Still, over all they're a pretty good reference.

    (I've never seen a compiler that didn't have strchr, and had never looked for or used strrchr--actually, I very seldom need either function [never in the case of strrchr]--but I find it's better to not assume something is ANSI and find out later that it isn't.)

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

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