Найти количество вхождений символа в текст

#include <stdio.h>
#include <stdlib.h>
 
/**
 * This function counts how many times the given character is in the given text.
 * The first argument (ch) is the character we are looking for.
 * The second argument (sentence) is the string (array of chars) where we are counting.
 * The function returns an integer, which is the count of the characters.
 * If the character is not present in the sentence, it returns 0.
 */
int how_many(char ch, char sentence[])
{
    int count = 0;
    int position;
 
    // **********************************************************************
 
    // HERE COMES YOUR CODE!
 
    // **********************************************************************
 
    return count;
}
 
/**
 * This function cleans up the input buffer after reading a character.
 * Don't worry about it, it just works.
 */
void clean_up(char ch)
{
    while (ch != EOF && ch != '\n')
        ch = getchar();
}
 
/**
 * This is the entry point of the program.
 * The user is asked for a character and a sentence. Then the function how_many()
 * is called and the result is displayed on the screen.
 */
int main()
{
    char ch; // a single character
    char sentence[1024]; // an array of characters (text, string), the capacity is 1024 chars (including the terminator)
 
    do {
        // Ask the user for a character.
        printf("Enter a character: ");
 
        // Read the character.
        // The function getchar() reads exactly one character. It is similar to scanf("%c", &ch), but it is easier to write.
        ch = getchar();
 
        // Clean up the input queue.
        // The reason is that the user usually enters two characters, the requested one and then Enter (newline).
        // We have to get rid of the newline, which stays in the input queue.
        clean_up(ch);
 
        // Test if the user entered a valid character.
        // If he/she entered a newline, tab or other special character, display an error message.
        if (ch < ' ' || ch > '~') {
            printf("That was not a legal character. Try again.\n");
        }
 
    // If the user entered an invalid character, go up and ask again.
    } while (ch < ' ' || ch > '~');
 
    // Ask the user for a sentence.
    printf("Enter a sentence: ");
 
    // Read the sentence.
    // Note we haven't used the gets() function, because it is unsafe (buffer overflow).
    // We used the safe alternative, although it is longer to write.
    fgets(sentence, 1024, stdin);
 
    // Count the characters in the sentence (call how_many()) and display the result.
    printf("The character '%c' is in the sentence %d times.\n", ch, how_many(ch, sentence));
 
    return 0;
}

int how_many(char ch, char sentence[])
{
    int count = 0;
    int position;
 
    // **********************************************************************
 
    // HERE COMES YOUR CODE!
    position=0;
    while (sentence[position]!=0)
    {
        if (sentence[position]==ch) count++;
        position++;
    }
 
    // **********************************************************************
 
    return count;
}

#include <string.h>
int mc(const char * s, const char c) {
    return ( s = strchr(s, c) ) ? 1 + mc(s+1, c) : 0;
}