Interview Question

This is a discussion on Interview Question within the C Programming forums, part of the General Programming Boards category; Hi I was wondering if someone could help me with this I always get this question alot in interviews and ...

  1. #1
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    Interview Question

    Hi I was wondering if someone could help me with this I always get this question alot in interviews and was hoping someone could help with an answers.

    if i had 2 strings str1"abcde" and str2 "bcd" create a function that would take both the strings and see if the str1 contains str2 if so return the index of str1 where the str2 is located. if not return -1

    Most of the times im using just a bunch of for loops and if statesment but is there a simpler approach to getting this done?

  2. #2
    Registered User claudiu's Avatar
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    Well to be honest I find interview questions that make you reinvent the wheel completely pointless in assessing someone. There is a function which does this already and it is part of the library.

    strstr()

    strstr - C++ Reference

    I'm pretty sure it's optimally implemented so you might want to take a look at its implementation.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  3. #3
    C++ Witch laserlight's Avatar
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    If you are being asked to describe an algorithm without actually implementing it, then perhaps the interviewer is looking for something sophisticated, e.g., Boyer-Moore. If you are being asked to implement an algorithm on paper, or on a computer but within a very short period of time, then perhaps the interviewer is just checking that you have practical programming skills to develop and implement a simple algorithm, in which case "a bunch of for loops and if statesment" would suffice.

    EDIT:
    Or, if there is no requirement to develop a simple algorithm, then an extension of claudiu's suggestion is best, i.e., to demonstrate practical programming skills by writing a wrapper around an existing function to do exactly what is required.
    Last edited by laserlight; 10-01-2010 at 12:34 PM.
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    Quote Originally Posted by kiros88 View Post
    if i had 2 strings str1"abcde" and str2 "bcd" create a function that would take both the strings and see if the str1 contains str2 if so return the index of str1 where the str2 is located. if not return -1
    Code:
    int foo(void) {
        return 1;
    }

  5. #5
    Registered User claudiu's Avatar
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    Quote Originally Posted by JohnGraham View Post
    Code:
    int foo(void) {
        return 1;
    }
    LOL. Nice one.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  6. #6
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by claudiu
    LOL. Nice one.
    Except that it demonstrates JohnGraham's failure to read the requirements properly since the function has no parameters. Furthermore, although the language is a little ambiguous, the description does state certain steps that must be done, even if precomputation due to known input was feasible.
    Last edited by laserlight; 10-01-2010 at 12:41 PM.
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  7. #7
    Registered User claudiu's Avatar
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    Quote Originally Posted by laserlight View Post
    Except that it demonstrates JohnGraham's failure to read the requirements properly since the function has no parameters. Furthermore, although the language is a little ambiguous, the description does state certain steps that must be done, even if precomputation due to known input was feasible.
    Actually, if we are talking requirements now, I think John got them spot on. The OP meant to say something else but said exactly what John pointed out. There is nowhere in the OP's original post a mention of the word "parameters".
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  8. #8
    Banned ಠ_ಠ's Avatar
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    Quote Originally Posted by claudiu View Post
    Actually, if we are talking requirements now, I think John got them spot on. The OP meant to say something else but said exactly what John pointed out. There is nowhere in the OP's original post a mention of the word "parameters".
    ... create a function that would take both the strings ...
    that sounds like a request for parameters to me
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  9. #9
    Registered User claudiu's Avatar
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    Quote Originally Posted by ಠ_ಠ View Post
    that sounds like a request for parameters to me
    Well, I think we are going off subject here, but it really isn't a request for parameters, or rather not one expressed correctly. "taking the strings" could very well mean storing them in some function variables:

    int func(void){
    char *str1 = "hello";
    char *str2 = "abcd";
    }

    Vague requirements are not really requirements.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  10. #10
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    Quote Originally Posted by claudiu View Post
    Vague requirements are not really requirements.
    if you ever try to implement that belief during an interview, please let me know ahead of time so I can come and watch


    and yes, I agree, your example does count as "taking the strings"
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  11. #11
    Registered User claudiu's Avatar
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    Quote Originally Posted by ಠ_ಠ View Post
    if you ever try to implement that belief during an interview, please let me know ahead of time so I can come and watch


    and yes, I agree, your example does count as "taking the strings"
    I do. I worked as a requirements engineer for several years.
    1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
    2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
    3. Get rid of conio.h and other antiquated DOS crap headers.
    4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.

  12. #12
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by claudiu
    "taking the strings" could very well mean storing them in some function variables:
    Excellent. Explain how did JohnGraham satisfy this interpretation of the "requirements".

    Quote Originally Posted by claudiu
    Vague requirements are not really requirements.
    Agreed, but if so, clarify, rather than interpret, or if you really want to interpret, then be bulletproof.
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