C language initial contact

C language initial contact
These days I have a preliminary understanding of the C language and read a lot of grammar knowledge.

# Include <stdio. h> int main () {printf ("hello world \ n"); return 0 ;}

 

This is my first simple program design. I believe most people start with hello word! In addition, it is easy to understand that the variable name should not be the same as the keyword. There is also a const keyword, which can keep the variable's initial value unchanged in the program, as long as the const keyword is placed before the type of the variable (it is also possible to put it later), for example: const int NUM = 7 (the variable name is generally in upper case, not mandatory) one difference between the scanf and printf functions: For float double, the replicator in printf is % f, but it is different in scanf. In scanf, float is % f, and double is % lf. In fact, in the double type, the replacement character in scanf is % lf with an additional l, and all others are the same!