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小奇 — Fri, 01 May 2009 11:36:00 GMT

#include <stdio.h>
#include <ctype.h>

/*
int atoi(char s[])
{
    int i = 0;
    int result, sign;
    while(isspace(s[i++])) ;
    for(sign = 1; '+' == s[i] || '-' == s[i]; ++i)
    {
        if ('-' == s[i])
            sign *= -1;
    }
    for(result = 0;isdigit(s[i]); ++i)
        result = result*10 + (s[i] - '0');
    return result * sign;
}
*/

double atof(char s[])
{
    double val, power;
    int i, sign;

    for (i = 0; isspace(s[i]); ++i)
        ;
    for (sign = 1; '+' == s[i] || '-' == s[i]; ++i)
        if ('-' == s[i])
            sign *= -1;

    for (val = 0.0; isdigit(s[i]); ++i)
        val = val*10.0 + (s[i] - '0');

    if ('.' == s[i])
        ++i;
    for (power = 1.0; isdigit(s[i]); ++i)
    {
        val = val*10.0 + (s[i] - '0');
        power *= 10;
    }
    return sign * val / power;
}

int atoi(char s[])
{
    return (int)atof(s);
}

int main(void)
{
    char s[50];
    scanf("%s", s);
    printf("%f\n%d\n", atof(s),atoi(s));
    return 0;
}

小奇 2009-05-01 19:36 发表评论

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