#include <stdio.h>
#include <ctype.h>
/* find most frequent letter in a string */
char mostFrequentLetter(const char *s) {
int freq[26] = {0}; /* frequency array */
/* count only alphabetic characters */
for (const char *p = s; *p; p++) {
if (isalpha((unsigned char)*p)) {
freq[tolower((unsigned char)*p) - 'a']++;
}
}
/* find index of max frequency */
int maxIndex = 0;
for (int i = 1; i < 26; i++) {
if (freq[i] > freq[maxIndex]) {
maxIndex = i;
}
}
return (char)('a' + maxIndex);
}
int main(void) {
const char *text = "abcabcaadbbccsedsade";
char result = mostFrequentLetter(text);
printf("Most frequent letter: %c\n", result);
return 0;
}
/*
run:
Most frequent letter: a
*/
