Error messages, and that's all - that code will not compile as C code, and if it did, it wouldn't run.
"Blocks" of code statements need curly brackets roundthem: so a
fucntion would need to have them to hold any useful code:
A line containing a single character variable name that isn't declared won't work at all.
Lines of code need to be separated by semicolons, all variables must be declared before they are used.
There is no "--" operator in C: there is a "-=" is that's what you meant.
loop requires three parts: (initializer; check; incrementor) - you can't just skip one and "hope for the best".
"O" is not the same as "0".
Being too lazy to type "printf" is not a good reason for using a
to make it quicker: it makes your code harder to read, harder to maintain, and less reliable.
Array's are not declared with round brackets, they need square brackets.
And so on.
Basically, that looks like someone spent most of the lesson on farcebook and tiktok while barely paying attention to the subject matter, and now needs to hand in homework - so they threw their shoes at a keyboard and hoped what they typed would compile ...