Is there a command like grep in Windows code example

Example 1: grep in windows

Use findstr in Windows with following command line structure:
findstr [/I] [/S] "substring" "regex_file_name"
/I   Case-insensitive search.
/S   Search files in subfolders recursively.

Example 2: windows cat grep equivalent

Use cat with find in Windows PowerShell
cat [Filename] | find "search"