First non-repeated character in a string in c

Write an efficient function to find the first non-repeated character in a string. For example, the first non-repeated character in "total" is 'o' and the first non-repeated character in "teeter" is 'r'.

Please see my solution and give me some feedback and suggestions for improving and optimizing it if needed.

#include <stdio.h>
#define SIZE 100                /* max size of input string */
#define LIM 5                   /* max number of inputs */
char repeat_ch(const char *);   /* return first non-repeated character */
int main(void)
{
    char line[SIZE];
    int i = 0;
    char ch;

    while(i < LIM && gets(line))
    {
        ch = repeat_ch(line);
        if(ch != NULL)
            printf("1st non-repeated character: %c\n", ch);
        else
                printf("There is no unique character in a string: %s\n", line);
        i++;
    }

}

char repeat_ch(const char *string)
{
    char array[130] = {0};
    char *p = string;

    /* store each character in array, use ascii code as an index for character
     * increment each time the same character appears in a string
     */
    while(*p)                               // stop when '\0' encountered
    {
        array[*p]+=1;
        p++;
    }
    while(*string)
    {
        if(array[*string] == 1)
            return *string;         // stop when unique character found
        string++;
    }

    return *string;
}