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String comparision

Posted on 2003-02-21
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Last Modified: 2010-04-15
Hello
I am new to c programming. I need to write own code for comparing two strings in C and not use inbuilt strcmp function. Can someone please help me with this.
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Question by:Leafox
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2 Comments
 
LVL 22

Expert Comment

by:grg99
ID: 7994639
Here's a huge hint:

start with i = 0;
compare str1[ i ] with str2[ i ].

if they're both '\0', then the strings are equal, return 0.

if they're not '\0', and  equal, move on to the next character (i+1)

now we've found two unequal characters at position i.

if the first one is > the second one, return +1
otherwise return -1.



That's pretty much it.

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Accepted Solution

by:
codez80 earned 200 total points
ID: 7995939
you can do it like this:


int string_compare(const char* str1, const char* str2)
{
  int i;

  i = strlen(str1) - strlen(str2);

  if (i != 0)
  {
     return i;
  }

  while (*str1)
  {
     i = *str1 - *str2;
     if (i != 0)
     {
        return i;
     }
     ++str1;
     ++str2;
  }  
 
  return 0;
}
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