C语言从字符串中提取数字

输入
A123.1c34.df.1 456.78cpc876.9er 849.1

输出 
123.1
1
456.78
876.9
849.1

直接代码

#include "stdio.h"
int CharToInt(char a){
	return a-'0';
}
int PointLen(double f)
{
    int i = 0,j=1;
    while (i++, f != (int)f) f *= 10;
	//return i-1;
	for(i;i>0;i--)
		j=j*10;
    return j;
}

int main(void){
	char aa[100]="A123.1c34.df.1 456.78cpc876.9er 849.1";
	char *a=aa;
	int i,num=0,flag_num=0,flag_point=0;
	double b[20];
	for (i=0;i<20;i++)
		b[i]=0;

	while(*a!='\0'){
		if(*a>='0' && *a<='9'){
			flag_num=1;
			if(flag_point==1)
				b[num] = b[num] + (double) CharToInt(*a)/(PointLen(b[num]));
			else
				b[num] = b[num]*10 + CharToInt(*a);
		}else{
			if(*a=='.'){
				if(flag_num==1){
					flag_point=1;
				}
			}else{
				if(flag_num==1)
					num++;
				flag_num=0;
				flag_point=0;
			}
		}
		a++;
	}
	for(i=0;i<=num;i++)
		printf("第%d个数为：%.4f\n",i,b[i]);	
	return 0;
}