// 模拟实现库函数的atof函数
#include
#include
#include
#include
double my_atof(char const *p)
{
double ret = 0;
int flag = 1;
int count = 0;
assert(p != NULL);
while (isspace(*p))
{
p++;
}
while (*p)
{
if (count)
{
count = count * 10;
}
if (*p == '+')
p++;
else if (*p == '-')
{
p++;
flag = -1;
}
else if (*p == '.')
{
count++;
p++;
}
else if (*p >= '0'&& *p <= '9')
{
ret = ret * 10 + (*p - '0');
p++;
}
else
return 0;
}
return ret*flag / count;
}
int main()
{
printf("%fn", my_atof(" +23.45"));
printf("%fn", my_atof(" -2.345"));
printf("%fn", my_atof("+234.5"));
printf("%fn", my_atof("-23.45"));
printf("%fn", my_atof("2.345"));
printf("%fn", my_atof("234.5"));
printf("%fn", my_atof(" ."));
printf("%fn", my_atof("12.3ab"));
return 0;
}