Mad Libs

Mad Libs is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Write a program to read a multiline story from the input. The story will be terminated with a blank line. Then, find each replacement to be made within the story, ask the user for a word to replace it with, and make all the replacements. Stop when there are none left and print the final story.

The input should be in the form:

<name> went for a walk in the park. <he or she>
found a <noun>. <name> decided to take it home.

It should then ask for a name, a he or she and a noun. (<name> gets replaced both times with the same value.)

C++

<lang cpp>#include <iostream>

1. include <string>

using namespace std;

int main() {

 string story, input;

 //Loop
 while(true)
 {
   //Get a line from the user
   getline(cin, input);

   //If it's blank, break this loop
   if(input == "\r")
     break;

   //Add the line to the story
   story += input;
 }

 //While there is a '<' in the story
 int begin;
 while((begin = story.find("<")) != string::npos)
 {
   //Get the category from between '<' and '>'
   int end = story.find(">");
   string cat = story.substr(begin + 1, end - begin - 1);

   //Ask the user for a replacement
   cout << "Give me a " << cat << ": ";
   cin >> input;

   //While there's a matching category 
   //in the story
   while((begin = story.find("<" + cat + ">")) != string::npos)
   {
     //Replace it with the user's replacement
     story.replace(begin, cat.length()+2, input);
   }
 }

 //Output the final story
 cout << endl << story;

 return 0;

} </lang>

Pike

this solution uses readline to make editing more convenient. <lang Pike>#!/usr/bin/pike

Stdio.Readline readln = Stdio.Readline();

void print_help() {

   write(#"Write a Story.

Names or objects in the story can be made variable by referencing them as <person> <object>, etc. End the story with an empty line.

Type show to read the story. You will be asked to fill the variables, and the the story will be shown.

Type help to see this message again. Type exit to quit.

"); }

void add_line(string input) {

   array variables = parse_for_variables(input);
   write("Found variables: %{\"%s\" %}\n", variables);
   story += input+"\n";

}

array parse_for_variables(string input) {

   array vars = Array.flatten(array_sscanf(input, "%*[^<>]%{<%[^<>]>%*[^<>]%}%*[^<>]"));
   return Array.uniq(vars);

}

mapping fill_variables(string story) {

   array vars = parse_for_variables(story);
   mapping variables = ([]);
   foreach(vars;; string name)
   {
       string value = readln->read(sprintf("Please name a%s %s: ", (<'a','e','i','o','u'>)[name[1]]?"":"n", name));
       if (value != "")
           variables["<"+name+">"] = value;
   }
   return variables;

}

void show_story(string story) {

   mapping variables = fill_variables(story);
   write("\n"+replace(story, variables));

}

void do_exit() {

   exit(0);

}

mapping functions = ([ "help":print_help,

                      "show":show_story,
                      "exit":do_exit,
                    ]);

string story = "";

void main() {

   Stdio.Readline.History readline_history = Stdio.Readline.History(512);
   readln->enable_history(readline_history);

   string prompt="> ";

   print_help();
   while(1)
   {
       string input=readln->read(prompt);
       if(!input)
           exit(0);
       if(input == "")
           show_story(story);
       else if (functions[input])
           functions[input]();
       else add_line(input);
   }

}</lang>

Sample output:

Write a Story.

Names or objects in the story can be made variable by 
referencing them as <person> <object>, etc.
End the story with an empty line.

Type show to read the story. You will be asked to fill the variables, 
and the the story will be shown.

Type help to see this message again.
Type exit to quit.

> <person> is a programmer.
Found variables: "person" 
> <he or she> created <website> for all of us to enjoy.
Found variables: "he or she" "website" 
> 
Please name a person: Michael
Please name a he or she: he
Please name a website: RosettaCode

Michael is a programmer.
he created RosettaCode for all of us to enjoy.
> 
Please name a person: Guilaumme
Please name a he or she: he
Please name a website: PLEAC

Guilaumme is a programmer.
he created PLEAC for all of us to enjoy.
> exit