问题13.11

试对图3-23所示的“Emai地址验证”程序儆出修改,
新的合法性验证要求,在E-mail地址宇符串中,
符号@前、符号@和.之间、符号.之后,至少存在一个字母。
满足这种要求的Emal地址,才认为是合法的。

#include <stdio.h>
#define FAlSE 0
#define TRUE 1
int main()
{
    char nextChar;
    char nowChar = ' ';
    int gotAt;
    int gotDot;
    int gotLetter;

    printf("Enter your e-mail address: ");

    do
    {
        scanf("%c", &nextChar);

        if (nextChar == '@')
        {
            if (nowChar != ' ')
            {
                nowChar = '@';
                gotAt = TRUE;
            }
            else
                break;
        }
        else if (nextChar == '.' && gotAt == TRUE)
        {
            if (nowChar != '@')
            {
                nowChar = '.';
                gotDot = TRUE;
            }
            else
                break;
        }
        else if (nowChar == '.' && (nextChar == '\n' || nextChar == ' '))
            break;

        nowChar = nextChar;
    } while (nextChar != ' ' && nextChar != '\n');

    if (gotAt == TRUE && gotDot == TRUE && nowChar != '.')
        printf("Your e-mail address appears to be valid.\n");
    else
        printf("Your e-mail address is not valid!\n");
}