C:calculate your cup size

bra.c

#include <ctype.h>
#include <errno.h>
#include <float.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* * * * * * * * * * * * * * * * * * * * *
 *
 * ./bra [your_underbust] [your_bust]
 * unit: cm
 *
 * for example:
 * ./bra 75.3 93.2
 *
 * then you will get:
 * Underbust is 75.3 cm, bust is 93.2 cm, bra is C75.
 *
 * * * * * * * * * * * * * * * * * * * * */


int get_cup_size(double underbust, double bust) {
    int delta;
    underbust = round(underbust);
    delta = (int)round(bust-underbust);
    if (delta % 2 == 0) {
        delta -= 1;
    }
    return (delta-11)/2;
}

int get_underbust_size(double underbust) {
    return (((int)underbust)+2)/5*5;
}

int main(int argc, char *argv[]) {
    char *csize_str = NULL, *endptr = NULL;
    double ub, b;
    int csize, ubsize;
    if (argc < 3) {
        fprintf(stderr, "Usage: %s your_underbust your_bust\n", argv[0]);
        return 5;
    }
    errno = 0;
    ub = strtod(argv[1], &endptr);
    if ((errno == ERANGE && (ub == DBL_MAX || ub == DBL_MIN)) || (errno != 0 && ub == 0)) {
        perror("strtod");
        return 3;
    }
    errno = 0;
    b = strtod(argv[2], &endptr);
    if ((errno == ERANGE && (b == DBL_MAX || b == DBL_MIN)) || (errno != 0 && b == 0)) {
        perror("strtod");
        return 4;
    }
    csize = get_cup_size(ub, b), ubsize = get_underbust_size(ub);
    if (ub <= b) {
        if (csize >= 0 && csize <= 26) {
            if (csize == 0) {
                csize_str = (char *)calloc(3, sizeof(char));
                strcpy(csize_str, "AA");
            } else {
                csize_str = (char *)calloc(2, sizeof(char));
                *csize_str = toascii(csize + 64);
                *(csize_str + 1) = '\0';
            }
            printf("Underbust is %f cm, bust is %f cm, bra is %s%d.\n", ub, b, csize_str, ubsize);
            free(csize_str);
        } else if (csize > 26) {
            fprintf(stderr, "Error: it\'s TOO BIG!!\n"); 
            return 1;
        } else {
            fprintf(stderr, "Error: it\'s TOO FLAT!!\n"); 
            return 3;
        }
    } else {
        fprintf(stderr, "Error: underbust is BIGGER than bust! Are you kidding me?!\n"); 
        return 2;
    }
    return 0;
}