This is the best course to learn from without any basic knowledge.

nightworkers1963

C is a little difficult, but it is a very basic language. 
Once you master C, you can learn other languages very easily. 
And, I will teach you NaDokCoding in a surprisingly easy way. 
Start C programming right now!

nadocoding

C Programming - From Introduction to Game Development

입문

초급

중급이상

C언어

Preferences

Variables, constants, input/output

Loop

Condition & Branch

Function

arrangement

Pointer

Multidimensional array

Structure

File Input/Output