How to find the most frequent vowel and consonants in the text in C

Question

For example the user entered this text: How arrree yooou

output ==> the most frequent vowel is: o
the most frequent consonants is: r

Not: Here 'e' also a duplicate, but the most frequent one is 'o', I am looking for the most frequent

/* Initializes frequency of all characters to 0 */
for(i=0; i<MAX_CHARS; i++)
{
    freq[i] = 0;
}
/* Finds frequency of each characters */
i=0;
while(str[i] != '\0')
{
    ascii = ((int)str[i]=='a' || str[i]=='e' || str[i]=='i' ||
       str[i]=='o' || str[i]=='u' || str[i]=='A' ||
       str[i]=='E' || str[i]=='I' || str[i]=='O' ||
       str[i]=='U');

    vowels++;

    freq[ascii] += 1;

    i++;
}

/* Finds maximum frequency */
max = 0;
for(i=0; i<MAX_CHARS; i++)
{
    if(freq[i] > freq[max])
        max = i;
}


printf("Maximum occurring character is '%c' = %d times.", max, freq[max]);

return 0;

}

Answer 1

Since I was explicitly asked in the comments, you could do something like:

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

struct max {
        int count;
        int value;
};
/* CAUTION: this incorrectly reports that '\0' is a vowel.
   exercise for the reader. */
int isvowel(int c) 
{ 
        return strchr("aeiou", tolower(c)) != NULL;
}
int isconsonant(int c) 
{ 
        return isalpha(c) && ! isvowel(c);
}

int main(void)
{
        int c;
        struct max consonant = {0}, vowel = {0};
        int count[256] = {0};
        while( ( c = fgetc(stdin)) != EOF ) {
                assert( c < 256 );
                count[c] += 1;
                if( isvowel(c) && count[c] > vowel.count ) {
                        vowel.count = count[c];
                        vowel.value = c;
                } else if( isconsonant(c) && count[c] > consonant.count ) {
                        consonant.count = count[c];
                        consonant.value = c;
                }
        }
        printf("%c appears %d time%s, %c appears %d time%s\n",
                vowel.value, vowel.count, vowel.count > 1 ? "s" : "",
                consonant.value, consonant.count, consonant.count > 1 ? "s" : "" );
        return 0;
}

Answer 2

Here's a short solution I had fun assembling.

#include <stdio.h>
#include <ctype.h>
#include <string.h>

void get_most_frequent(int count[], const char const* set, char* letter, int *number)
{
    *letter = '\0';
    *number = 0;
    for(int i=0; set[i]; ++i)
    {
        *letter = (count[set[i]-'a'] > *number)? set[i]            : *letter;
        *number = (count[set[i]-'a'] > *number)? count[set[i]-'a'] : *number;
    }
}

int main(void) {
    const char str[] = "My sample text, that Contains many vowels And consanants of all shapes and sizes; along with UPPER and LOWER cases.";
    const char vowels[] = "aeiou";
    const char cnsts[] = "bcdfghjklmnpqrstvwxyz";
    int max;
    char letter;
    int count[26] = {};

    for(int i=0; str[i]; ++i)
    {
        count[tolower(str[i])-'a'] += !!isalpha(str[i]);
    }

    // Most frequent vowel
    get_most_frequent(count, vowels, &letter, &max);
    printf("Vowel %c appears %d times\n", letter, max);

    // Most frequent consonant
    get_most_frequent(count, cnsts, &letter, &max);
    printf("Consonant %c appears %d times\n", letter, max);

    return 0;
}

Output

Success #stdin #stdout 0s 4532KB
Vowel a appears 13 times
Consonant s appears 11 times

Answer 3

Since you've already figured out the most frequent vowel/ consonant, you might pass it to a switch case like this:

switch(c)
    {
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
        case 'A':
        case 'E':
        case 'I':
        case 'O':
        case 'U':
                    printf("\nThe most frequent vowel is: %c", c);
                    break;
        default:
                    printf("\nThe most frequent consonant is: %c", c);
    }

In case if you just want to know whether the most repeated character is a vowel/ consonant, the switch case could do the job. I haven't cheked your entire code, but if here:

printf("Maximum occurring character is '%c' = %d times.", max, freq[max]); 

max contains the most frequent character in your string, you could simply pass max to the switch case and print the output from the switch case itself.