从字符串中取数

static char* p;
if(str)
    p = str;
double num = 0;
while(*p && !(*p>='0'&&*p<= '9'))
    ++p;
if(*p == 0)
    return -1;
while(*p>='0' && *p<='9') {
    num = num*10+*p-'0';
    ++p;
}
if(*p == '.') {
    ++p;
    double i = 10;
    while(*p>='0' && *p<='9') {
        num += (*p-'0')/i;
        ++p;
        i *= 10;
    }
}

return num;

转载From：https://www.cnblogs.com/VincentValentine/p/5677353.html

贴在这里，作为自己日后回顾学习使用，如有冒犯，本人可立即删除！