ascii.c

ascii.c

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

int NUMASCII = 127;

struct Ascii {
	int code; // ascii character code
	int occurrences; // number of occurrences
};

int swap(const void *a, const void *b) {
    const struct Ascii *character1 = a;    
    const struct Ascii *character2 = b;
    return character2->occurrences - character1->occurrences;
}

int main(int argc, char *args[]) {
	struct Ascii ascii[NUMASCII];
	int counter = 0;
	for (struct Ascii *a = ascii; a < ascii + NUMASCII; a++) {
		a->code = counter++;
		a->occurrences = 0;
	}

	char c;
	while((c = getchar()) != EOF) {
		int code = c;
		ascii[code].occurrences += 1;
	}

	qsort(ascii, NUMASCII, sizeof(*ascii), swap);

	for (int i = 0; i < NUMASCII; ++i) {
		if (ascii[i].occurrences > 0) {
			printf("%c: %i\n", (char)ascii[i].code, ascii[i].occurrences);
		}
	}
}