After a few computer science courses, students may start to get the feeling that programs can always be written to solve any computational problem. Writing the program may be hard work. For example,...

C++

Add a search command that asks the user for a string and finds the first line that contains that string. The search starts at the first line currently displayed and stops at the end of the file. If the string is found, the line that contains it is displayed at the top. In case the user enters a string X that does not occur in the file, the program should print the error message:

ERROR: string "X" was not found.

Attached is the first lines of the .txt file

Extracted text: After a few computer science courses, students may start to get the feeling that programs can always be written to solve any computational problem. Writing the program may be hard work. For example, it may involve learning a difficult technique. And many hours of debugging. But with enough time and effort, the program can be written. So it may come as a surprise that this is not the case: there are computational problems for which no program exists. And these are not ill-defined problems (Can a computer fall in love?) or uninteresting toy problems. These are precisely defined problems with important practical applications.