How do you compare strings?

Answer 1

In most programming languages you will be relying on pre-existing library functions for all your string comparison needs.

The algorithm is:

• Consider both strings as arrays of characters (depending on the language, they will either have a specified maximum length, eg in Pascal or a terminating symbol - usually a zero - eg in C and C++)
• Iterator n represents the position in the character string, with its' initial value representing the first index in the array. If the language permits it, you can use pointer arithmetic instead.
• For each character in a string:

1. Take the n-th character from string 1
2. Take the n-th character from string 2
3. Compare both characters (the exact comparison method may vary)
4. If not equal, return false
5. Increase n by 1

• If reached end of string, return true

Here is an example function in C (returning a 1 if the strings are identical, 0 if not). This implementation forgoes use of an iterator in favor of pointer arithmetic and comparison in favor of XORing the characters with each other (a XOR of identical values returns a zero):

int string_compare(char* a, char* b)

{

while (*a)

{

if (*a++^*b++) return 0;

}

return 1;

}