Thread: Transferring non-repeated characters to another string

Code:

#include<stdio.h>#include<string.h>
#define size 50


void count(char s[size]);


main(){
    char str[size];
    int num = 7;


    printf("Enter a string: ");
    scanf("%s", str);


    count(str);
}


void count(char s[size]){
    char str[size];
    int str_cnt[size] = {}, i, j, str_s = strlen(s);


    for(i = 0; i < str_s; i++){
        if(strlen(str) == 0){
            str[0] = s[i];
            str_cnt[0]++;
            str[1] = '\0';
        }
        else{
            //check if character already exists
            for(j = 0; j < strlen(str); j++){
                //if it exists then increment
                //printf("%c, %c\n", s[i], str[j]);
                if(s[i] == str[j]){
                    str_cnt[j]++;
                    break;
                }
            }
            
            //if not, then add to the character array then increment
            if(j == strlen(str)){
                str_cnt[j]++;
                str[j] = s[i];
                str[j+1] = '\0';
            }
        }
    }


    for(i = 0; i < str[i] != '\0'; i++){
        printf("%c - %d\n", str[i], str_cnt[i]);
    }
}

This program will count how many times a character was used in a word. Now, I want to modify it so that it will remove letters that was used more than 1. Since I do not know how to remove a character from a string, my idea is to transfer the letters that were only used once to another string.
Example:
Enter string: google
g-2
o-2
l-1
e-1
Output: le

Is this possible? Or is removing(if such function exists) a character much easier?

It's not easier to remove a character in place, it's possible to shift all characters back one step to achieve that, but it's going to be simpler IMO to copy to a new array.

There is no pre-built function in C to remove repeating char's, in place.

There is a simpler, more efficient way to do this job, however. All letter values in the computer character set, are contiguous, and represented as small 8 bit int's. So it's easy to treat them as indices to an array of int's.

I see your eyes starting to glaze over there, but stick with me!

Let's take an example where the input is all lowercase, to make it easier. If you printf("%c",97), in a program, what do you see? What about printf("%d",97); what do you see now?

Char's are simply small range int's, with only 8 bits.

So if we had an array and were trying to count all the occurrences , we could count them like so:

Code:

for(each i in the int array of count[]) {
    count[i] = 0;
}
//now
for(each letter in the string[]) {
   count[string[i]]++;
}

Now print count, and each count[i] that == 1, you want to print. Don't print the rest.