#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <ctype.h>

#define ATOX(name, type) \
    type name(const char* s) { \
        for(; isspace(*s); s++); \
        int neg = 0; \
        switch (*s) { \
            case '-': \
                neg = 1; \
                /* FALLTHRU */ \
            case '+': \
                s++; \
                break; \
        } \
        type num = 0; \
        for (; *s == '0'; s++); \
        for (; isdigit(*s); s++) { \
            num *= 10; \
            num += *s - '0'; \
        } \
        return num * (neg ? -1 : 1); \
    }

ATOX(atoi, int)
ATOX(atol, long int)
ATOX(atoll, long long int)

char itoc(int i) {
	if(i < 10) {
		return '0' + i;
	} else {
		return 'a' + (i - 10);
	}
}

int ctoi(char c) {
    if(c < 'A') {
		return c - '0';
	} else if(c < 'a') {
		return c - 'A' + 10;
	} else {
		return c - 'a' + 10;
	}
}

#define UXTOA(type, name) \
    char *name(unsigned type n, char *buffer, int radix) { \
        if (n == 0) { \
            buffer[0] = '0'; \
            buffer[1] = '\0'; \
            return buffer; \
        } \
        char *start = buffer; \
        for (; n; n /= radix) { \
    		*buffer++ = itoc(n % radix); \
    	} \
        *buffer-- = '\0'; \
        while(buffer > start) { \
    		char tmp = *start; \
    		*start++ = *buffer; \
    		*buffer-- = tmp; \
    	} \
        return buffer; \
    }

UXTOA(int, utoa)
UXTOA(long int, ultoa)

#define XTOA(type, name) \
    char *name(type n, char* buffer, int radix) { \
        if (n == 0) { \
            buffer[0] = '0'; \
            buffer[1] = '\0'; \
            return buffer; \
        } \
        if (n < 0) { \
            *buffer++ = '-'; \
            n = -n; \
        } \
        char *start = buffer; \
        for (; n; n /= radix) { \
    		*buffer++ = itoc(n % radix); \
    	} \
        *buffer-- = '\0'; \
        while(buffer > start) { \
    		char tmp = *start; \
    		*start++ = *buffer; \
    		*buffer-- = tmp; \
    	} \
        return buffer; \
    }

XTOA(int, itoa)
XTOA(long int, ltoa)

char *ftoa(float f, char *buffer) {
    char *b = buffer;
    if (f < 0 || f == -0)
        *buffer++ = '-';
    int n, i=0, k=0;
    n = (int) f;
    while (n > 0) {
        f /= 10;
        n = (int)f;
        i++;
    }
    *(buffer+i) = '.';
    f *= 10;
    n = (int) f;
    f -= n;
    while ((n > 0.1) || (i > k)) {
        if (k == i)
            k++;
        *(buffer+k) = '0' + n;
        f *= 10;
        n = (int) f;
        f -= n;
        k++;
    }
    *(buffer+k) = '\0';
    return b;
}

#define STRTOX(name, type) \
    type name(const char *s, char **endptr, int radix) { \
        *endptr = NULL; \
        for(; isspace(*s); s++); \
        int neg = 0; \
        switch (*s) { \
            case '-': \
                neg = 1; \
                /* FALLTHRU */ \
            case '+': \
                s++; \
                break; \
        } \
        if (!radix) { \
            if (*s == '0') { \
                s++; \
                if (*s == 'x' || *s == 'X') { \
                    s++; \
                    radix = 16; \
                } else { \
                    radix = 8; \
                } \
            } else { \
                radix = 10; \
            } \
        } \
        for (; *s == '0'; s++, *endptr = (void*) s); \
        type num = 0; \
        for (; isdigit(*s); s++, *endptr = (void*) s) { \
            num *= radix; \
            num += *s - '0'; \
        } \
        return num * (neg ? -1 : 1); \
    } 

STRTOX(strtoi, int)
STRTOX(strtol, long int)
STRTOX(strtoll, long long int)