エクセル列名変換問題

excelColConv.c

/*
	エクセル列名変換問題

	NOTE：
		A = 1, B = 2, .....
		AA = 27.....
		XFD = 16384
		
	@created at: 2012-01-31
	@author: lithtle
*/

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

#define CHARACTER_A 65
#define ALPHABETS 26

int
argvCheck(char *arg)
{
	int c;
	
	while(*arg)
	{
		c = *arg;
		if(!isalpha(c))
		{
			return 1;
		}
		arg++;
	}
	return 0;
}

int
i_pow(int i, int j)
{
	int ret = 1;
	int k;
	
	for(k = 0; k < j; k ++)
	{
		ret *= i;
	}
	
	return ret;
}

int
conv(char *s)
{
	int ret = 0;
	int c;
	int len;
	
	while(*s)
	{
		c = *s;
		len = strlen(s);
		
		c = toupper(c);
		ret += i_pow(ALPHABETS, len - 1) * (c - CHARACTER_A + 1);
		
		s++;
	}
	
	return ret;
}

int
main(int argc, char *argv[])
{
	if(argc != 2 || argvCheck(argv[1]))
	{
		fprintf(stderr, "invalid argument\n");
		fprintf(stderr, "usage: %s [string]\n", argv[0]);
		exit(1);
	}
	
	printf("%s converts into => %5d\n", argv[1], conv(argv[1]));
	
	return 0;
}