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So I'm a bit stumped on this, I'm reading a file with two types of lines that contain data, and they are started by a number followed by a comma. I need a way in order to match the lines with the same starting digit into a single line and output that. How would I even get started?
I'd do this by reading each line in two parts: the stuff before the comma, and the stuff after it.
Then I'd have a map (or unordered_map) with the value before the comma as the key, and the rest as the value associated with it.
std::map<std::string, std::string> data;
std::string key, value;
while (std::getline(infile, key, ',')) {
std::getline(infile, value);
data[key] += value;
}
Then (presumably) you'd want to write out the values:
for (auto const &v : data)
std::cout << v.first << ":" << v.second << "\n";
Related
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I've asked to write code that gets a char array(sentence), if the there is an 'i' in the sentence I need to add the letter 'b' the letter 'i' again like this example:
pig -> pibig
I tried to use string.h functions but I didn't succeed to make it right.
Use std::string in string header file, and std::string::insert whenever you need to insert a char in string:
std::string my_string = "my satringa";
for (size_t i = 0; i < my_string.length(); ++i)
{
if (my_string.at(i) == 'a')
{
my_string.insert(i + 1, "b");
}
}
std::clog << my_string << std::endl;
Output:
> my sabtringab
If you are forced to use C-style strings, don't worry do all of your operations on std::string and then take the underlying stored string with std::string::c_str() as a C-style string (and don't forget to take a copy).
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I am making a shopping list program. For this program, I need to be able to type in a user input that accepts both number (1564, 121,1, etc) and word (hello, goodbye, etc) combinations. The program reads numbers just fine, but it cannot process words. Thank you in advance. The part of the code I am stuck with is below:
int code, option, count = 0;
double quantity, price, cost;
string description;
cin >> code;
while ((code != 123456789) && (count < 2))
{
cout << "Incorrect code, try again \n";
cin >> code;
count++;
if (count == 2)
{
cout << "max # of tries reached. Goodbye. \n";
system("pause");
}
}
Your code variable is now an int. If you wanted that to be a string, declare it so: std::string code;. Note that you might need to #include <string> in the very beginning. Also, if you want to compare it with numbers, either you call something like atoi() (string has .cstr()), or better yet, you might just compare it with "123456789". HTH.
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I receive text with special characters (such as á) so I have to manually search and replace each one with code (in this case "á")
I would like to have code to search and replace such instances automatically after user input. Since I'm a noob, I'll show you the code I have so far - however meager it may be.
// Text fixer
#include <iostream>
#include <fstream>
#include <string>
int main(){
string input;
cout << "Input text";
cin >> input;
// this is where I'm at a loss. How should I manipulate the variable?
cout << input;
return 0;
}
Thank you!
An easy method is to use an array of substitution strings:
std::string replacement_text[???];
The idea is that you use the incoming character as the index into the array and extract the replacement text.
For example:
replacement_text[' '] = " ";
// ...
std::string new_string = replacement_text[input_character];
Another method is to use switch and case to convert the character.
Alternative techniques are a lookup table and std::map.
The lookup table could be an array of mapping structures:
struct Entry
{
char key;
std::string replacement_text;
}
Search the table using the key field to match the incoming character. Use the replacement_text to get the replacement text.
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How could I access a text file and go through word by word. I understand how to open the file but just not how to pull out each word one by one. I think it has something to do with arrays?
Simply:
#include <fstream>
#include <iostream>
int main()
{
std::fstream file("table1.txt");
std::string word;
while (file >> word)
{
// do whatever you want, e.g. print:
std::cout << word << std::endl;
}
file.close();
return 0;
}
word variable will contain every single word from a text file (words should be separated by space in your file).
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I need to parse the following file so it takes the item as a string then skip the # sign and then take the price as a float.
text file:
hammer#9.95
saw#20.15
shovel#35.40
how would I go about doing this?
In case when you have std::string in presented format you could use something like this:
std::string test {"test#5.23"};
std::cout << std::stof(std::string{test.begin() + test.rfind('#') + 1, test.end()});
Note that std::stof is C++11 function
Read the file line by line into a string. Find # and parse second part as float.
std::ifstream file("input.txt");
for (std::string line; std::getline(file, line); )
{
auto sharp = line.find('#'); // std::size_t sharp = ...
if (sharp != std::string::npos)
{
std::string name(line, 0, sharp);
line.erase(0, sharp+1);
float price = std::stof(line);
std::cout << name << " " << price << "\n";
}
}
Note: I didn't some error checking, do them yourself as an exercise. and also you should know about std::string, std::ifstream, std::getline and std::stof.