CODEWITHSUNDEEP
c++cin
Thor
Thor

Reputation: 10028

How to remove all punctuation marks from a sentence?

I'm new to C++ and is trying to solve the beginner's problem of trying to remove all punctuation marks from a sentence. Below is the code I have came up with. However, when I entered "Hello! Hello!", the compiler output "Hello" instead of "Hello Hello" (which is what I would expect).

Why is this happening?

#include <iostream>
#include <string>
using namespace std;

int main(){

    cout << "please enter a sentence which include one or more punctuation marks" << endl;    
    string userInput;
    string result;
    cin >> userInput;
    decltype(userInput.size()) n;
    for (n = 0; n < userInput.size(); n++){
        if(!ispunct(userInput[n])){
            result += userInput[n];
            cout << result << endl;
        }
    }
    return 0;
}

Input:

Hello! Hello!

Compiler output:

Hello

Upvotes: 2

Views: 519

Answers (3)

paddy
paddy

Reputation: 63461

As others already said, you use getline to read a whole line of text.

I wanted to also point out there are functions in <algorithm> that make this kind of thing much cleaner. Instead of looping over your string, you can use std::remove_if.

#include <iostream>
#include <string>
#include <algorithm>

int main()
{
    std::string line;
    while( std::getline( std::cin, line ) )
    {
        line.erase( std::remove_if( line.begin(), line.end(), ispunct ), line.end() );
        std::cout << line << std::endl;
    }
    return 0;
}

Upvotes: 1

SegFault
SegFault

Reputation: 2546

Try using the getline() function. Read about it here.

Welcome to C++! Read up about stringstreams they are very good at manipulating strings

Upvotes: 1

Jerry Coffin
Jerry Coffin

Reputation: 490048

When you do cin >> userInput, it only reads up to the first white-space character in the input stream.

You probably want to use std::getline instead (it'll read the entire line, by default).

Upvotes: 4

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