//atoi的实现
while (num)
{
*ptr++ = string[num % radix];
num /= radix;
if (num
*ptr++ = string[num];
*ptr = '\0';
break;
}
}
j = ptr - str - 1;
for (i = 0; i <(ptr - str) / 2; i++)
{
int temp = str[i];
str[i] = str[j];
str[j--] = temp;
}
return str;
}