Contoh konversi integer menjadi string representasi

int-str-repr.c

// need link with math lib hence link with -lm, e.g.:
// gcc int-str-repr.c -lm
// or simply using tcc like:
// tcc int-str-repr.c
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

void printSingleDigit(int num) {
	const char* repr[10] = {
		"puluh", "se", "dua", "tiga", "empat",
		"lima", "enam", "tujuh", "delapan", "sembilan"
	};
	printf("%s", repr[num]);
}

void printTens(int magn) {
	const char* tens[] = {"puluh", "ratus", "ribu"};
	printf("%s", tens[(magn-1)%3]);
}

void printConverted(int);

int printAndGetNum(int num, int base, const char *label) {
	int denom = (int)pow(10, base);
	printConverted(num / denom);
	printf(" %s ", label);
	return num % denom;
}

void printConverted(int num) {
	bool teen = false;
	while (num > 9) {
		if (num > 10 && num < 20) {
			num = num % 10;
			printSingleDigit(num);
			if (num != 1) printf(" ");
			printf("belas");
			teen = true;
			break;
		}

		int magn = (int)log10((float)num);
		int denum = (int)pow(10, magn);
		int digit1 = num / denum;
		if (magn >= 9) {
			num = printAndGetNum(num, 9, "milyar");
		} else if (magn >= 6) {
			num = printAndGetNum(num, 6, "juta");
		} else if (magn >= 3) {
			num = printAndGetNum(num, 3, "ribu");
		} else {
			printSingleDigit(digit1);
			if (digit1 != 1) printf(" ");
			printTens(magn);
			num = num % denum;
			printf(" ");
		}
	}
	if (!teen) {
		if (num == 1) printf("satu");
		else if (num == 0);
		else printSingleDigit(num);
	}
}

int printSingleDigit2(char *dst, int num) {
	char* repr[10] = {
		"puluh", "se", "dua", "tiga", "empat",
		"lima", "enam", "tujuh", "delapan", "sembilan"
	};
	int len = 0;
	for (char* s = repr[num], c = *s; c != '\0'; s++, c = *s, len++) {
		*dst = c;
		dst++;
	}
	*dst = '\0';
	return len;
}

int printTens2(char *dst, int magn) {
	char* tens[] = {"puluh", "ratus", "ribu"};
	int len = 0;
	for (char *s = tens[(magn-1)%3], c = *s; c != '\0'; s++, c = *s, len++) {
		*dst = c;
		dst++;
	}
	*dst = '\0';
	return len;
}

int printConverted2(char *dst, int num);

int printAndGetNum2(char *dst, int num, int base, const char *label, int labelen, int *outmagn) {
	int denom = (int)pow(10, base);
	int len = printConverted2(dst, num / denom);
	dst += len;
	*dst = ' ';
	dst++;
	strcpy(dst, label);
	dst += labelen;
	*dst = '\0';
	len += labelen + 1;
	*outmagn = num % denom;
	if (*outmagn > 9) {
		*dst = ' ';
		dst++;
		len++;
		*dst = '\0';
	}
	return len;
}

int printConverted2(char *dst, int num) {
	bool teen = false;
	int len = 0;
	if (num == 0) {
		strcpy(dst, "nol");
		*(dst+3) = '\0';
		return 3;
	}
	if (num < 0) {
		const char neg[] = "negatif ";
		strcpy(dst, neg);
		len = (sizeof(neg) / sizeof(char))-1;
		dst += len;
		*dst = '\0';
		num = -1*num;
	}
	while (num > 9) {
		if (num > 10 && num < 20) {
			num = num % 10;
			int singlen = printSingleDigit2(dst, num);
			len += singlen;
			dst += singlen;
			if (num != 1) {
				*dst = ' ';
				dst++;
				len++;
			}
			strcpy(dst, "belas");
			dst += 5;
			len += 5;
			*dst = '\0';
			teen = true;
			break;
		}

		int magn = (int)log10((float)num);
		int denum = (int)pow(10, magn);
		int digit1 = num / denum;
		if (magn >= 9) {
			int plen = printAndGetNum2(dst, num, 9, "milyar", 6, &num);
			dst += plen;
			len += plen;
		} else if (magn >= 6) {
			int plen = printAndGetNum2(dst, num, 6, "juta", 4, &num);
			dst += plen;
			len += plen;
		} else if (magn >= 3) {
			int plen = printAndGetNum2(dst, num, 3, "ribu", 4, &num);
			dst += plen;
			len += plen;
		} else {
			int singlen = printSingleDigit2(dst, digit1);
			len += singlen;
			dst += singlen;
			if (digit1 != 1) {
				*dst = ' ';
				dst++;
				len++;
			}
			int maglen = printTens2(dst, magn);
			dst += maglen;
			len += maglen;
			*dst = ' ';
			dst++;
			len++;
			num = num % denum;
		}
	}
	if (!teen) {
		if (num == 1) {
			strcpy(dst, "satu");
			dst += 4;
			len += 4;
		}
		else if (num == 0) {
			dst--;
			len--;
		}
		else {
			int singlen = printSingleDigit2(dst, num);
			dst += singlen;
			len += singlen;
		}
		*dst = '\0';
	}
	return len;
}

void checkNum(char *buf, int num) {
	int len = printConverted2(buf, num);
	printf("num %d repr as '%s' with buf length %d\n", num, buf, len);
	memset(buf, '\0', len);
}

int main(int argc, char* argv[]) {
	/*
	if (argc < 2) {
		printf("provide arg as num");
		exit(EXIT_FAILURE);
	}
	int num = atoi(argv[1]);
	*/
	int numtest[] = {
		        1
		,      18
		,      38
		,     585
		,    8525
		,   38595
		,  739585
		, 9717585
	};
	printf("===print conversion\n");
	for (int i = 0; i < sizeof(numtest)/sizeof(numtest[0]); i++) {
		printf("num %d is repr as '", numtest[i]); printConverted(numtest[i]); printf("'\n");
	}
	printf("===string conversion\n");
	char buf[1024];
	for (int i = 0; i < sizeof(numtest)/sizeof(numtest[0]); i++) {
		checkNum(buf, numtest[i]);
	}

	for(int i = -21; i <= 100; i++) {
		checkNum(buf, i);
	}
	checkNum(buf, 500);
	return 0;
}