Problem B: 编写函数：String to Double (II) (Append Code)

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <math.h>

#include <malloc.h>

#define  MAX_STR_LEN  12

double strToDouble(char str[])

{

 

    if(str[0]=='\0') return 0;

    int i,j=0,n,k=0,h=0,flag=0;

     double sum=0,m=0.1,sum1=0,sum2;  char c[20],d;

     n=strlen(str);

     for(i=0;i<n;i++)

     {

         if(isdigit(str[i]))

          {sum=sum*10+str[i]-'0';flag++;}

        if(str[i]=='.') {i++;break;}

     }

     for(;i<n;i++)

     {

         if(str[i]=='-'||str[i]=='+') c[j++]=str[i];

         if(isdigit(str[i]))

         {sum1+=(str[i]-'0')*m;m/=10;}

     }

     sum2=sum+sum1;

     for(i=0;i<n;i++)

     {

         if(isdigit(str[i]))  break;

         else if(str[i]=='+'||str[i]=='-')

            {  if(str[i]=='-')  sum2=-sum2;break; }

     }

    return sum2;

}

 

int main()

{

    char s[MAX_STR_LEN];

    while(gets(s) != NULL)

        printf("%lg\n", strToDouble(s));

    return 0;

}

C语言