Counting reapetance of a word in a string

[Saeid87]

Dear Friends, is there a premade function to count reapetance of a characters in a string or an array in C? if not what is your suggested approach to do it?

for example:

the input is: ARIZONA
Result is : 2111112

input is: KISS
output : 1122


Thanks.

[laserlight]

It sounds like you are trying to count the frequency of characters, not words.

[Saeid87]

Edited the title..thanks for informing

[laserlight]

Well, a simple solution, assuming 8-bit bytes, is to create an array of 256 integers. These will be the frequencies, with the values of the characters as the corresponding indices. As such, you initialise this array to contain zeroes, then loop over the string and directly increment the corresponding frequency. Note that you may need to cast the char to unsigned char since char can be signed.

[Saeid87]

wow can you please break it down a little bit? I could not get the idea maybe a little example please

[System_159]

I had this project in school as well.

Think of it as having a place in an integer array for each of letter of the alphabet(A = 0, B = 1, C = 2, etc...).
Iterate through the word once adding 1 to that letters index.
Once you're all the way through the word, go back to the start.
Iterate through again, but this time instead of adding 1, just read the value in that letters index.

It's easier to think about with just the alphabet, but much easier to actuall implement with all 256 characters.