The 163rd day to learn web

Today is the fifth day to learn cs50 week1 short videos.But cs50 has the newer videos. Remmber the values  on the both sides of the equal symbol , Assignment from left to right,unsigned int can increase the positive integer of 2 billion  to a positive integer of 4 billion  .void type returns nothing, for example, printf and main function.Float type can be double，so pi takes on places, from 7 to 30, from 32bits to 64bits.okay.