十进制十六进制互转、数字转字符、日期转总天数

#include<stdio.h>
/*
    将十六进制转换成十进制输出
*/
void hex2dec(char *hex)
{
    int result = 0;
    int temp;
    while(*hex != '\0')
    {
        if(*hex>='0' && *hex<='9')
        {
            temp = *hex - '0';
        }
        else if(*hex>='A' && *hex<='F')
        {
            temp = *hex - 'A' + 10;
        }
        else if(*hex>='a' && *hex<='f')
        {
            temp = *hex - 'a' + 10;
        }
        result += temp;
        if(*(hex+1) != '\0')
        {
            result = result*16;
        }
        hex++;
    }
    printf("%d", result);
}

/*
    将十进制转换成十六进制输出
*/
void dec2hex(int dec)
{
    int hex;
    if(dec<16)
    {
        hex = dec;
    }
    else
    {
        //余数
        int x = dec%16;
        //对商进行递归
        dec2hex(dec/16);
        //递归最外层最后输出
        hex = x;
    }
    if(hex>9)
    {
        printf("%c", hex-10+'A');
    }
    else
    {
        printf("%c", hex+'0');
    }
}

/*
    将整数转换成字符串输出
*/
void int2char(int n)
{
    int r = n%10;
    int s = n/10;
    if(s==0)
    {
        printf("%c" ,n+'0');
    }
    else
    {
        int2char(s);
        printf("%c", r+'0');
    }
}
/*
    给定日期是当年的第几天
*/
int date2TotalDays(int year, int month, int day)
{
    int i,totalDays=0;
    int months[] = {31,28,31,30,31,30,31,30,31,30,31,30};
    if((year%4==0 && year%100!=0) || year%400==0)
    {
        months[1] = 29;
    }
    for(i=0; i<month-1; i++)
    {
        totalDays += months[i];
    }
    totalDays += day;
    return totalDays;
}
void main()
{
    hex2dec("12cd");
    printf("\n");
    dec2hex(1000);
    printf("\n");
    int2char(483);
    printf("\n");
    printf("%d", date2TotalDays(2014,3,7));
}