Beginner Error with "getline"

Question

this is my first time posting a question so I hope I'm getting this right. Anyways, I'm trying to create a program to ask the user for a string, count the types and numbers of letters, then output the frequency of the letters. So far I'm having an error with even getting the right input, and just can't figure out what the issue is. My (relevant) code is:

#include <iostream>
#include <iomanip>
#include <string>
#include <vector>

using namespace std;    

string getPhrase(const string & phrase);  //Function for gathering string input
int main()
{
     const string phrase;
     getPhrase(phrase);
     ...
}

string getPhrase(const string &phrase)
{
   cout<<"Enter phrase: "
   getline(cin, phrase);

   return (phrase);
}

When I run, this I get the error:

freq.cpp: In function ‘std::string getPhrase(const std::string&)’:
freq.cpp:21: error: no matching function for call to ‘getline(std::istream&, const
std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)’

I have no idea what I'm doing wrong, and just can't seem to find anything online that's relevant to what I'm doing.

What was your reasoning for making `phrase` a `const` variable? I'd like to know so we can help you understand why it's wrong. :) — Joseph Mansfield, Apr 09 '13 at 22:42
If you're a beginner, you absolutely should learn 21st-century C++ and never ever say `abusing namespace std;`. Stuffy pseudo-professors in the 1980s came up with that, but that doesn't mean it's acceptable. — Kerrek SB, Apr 09 '13 at 22:42
@sftrabbit Its a template given to me by my intro C++ class haha, I removed the "const" part and used some "std::"'s in certain places like suggested below and its finally working — user2250690, Apr 09 '13 at 22:55
@KerrekSB its an intro C++ class, and its just the way I'm being taught right now — user2250690, Apr 09 '13 at 22:55

score 1 · Answer 1 · answered Apr 09 '13 at 22:40

1

Your getPhrase should look like this:

std::string getPhrase()
{
    std::string result;
    std::cout << "Enter phrase: ";
    std::getline(std::cin, result);
    return result;
}

Then:

int main()
{
    std::string phrase = getPhrase();

    // ...
}

answered Apr 09 '13 at 22:40

Kerrek SB

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score 0 · Answer 2 · answered Apr 09 '13 at 22:40

 const string phrase;

remove const in function parameter and local variable declaration since otherwise you can't accept user input to a const variable, which means nonchangable/ non-modifiable.

Like the following:

string getPhrase(string & phrase);  //Function for gathering string input
int main()
{
     string phrase;
     getPhrase(phrase);
     //...
}

score 0 · Answer 3 · answered Apr 09 '13 at 22:40

Notice that phrase is a const string. That means it's constant and can't be modified. Therefore you can't use getline to set phrase to the user's input.

You should declare phrase with string phrase; and then make the parameter of getPhrase a non-const reference.

string getPhrase(string& phrase);  //Function for gathering string input
int main()
{
     string phrase;
     getPhrase(phrase);
     ...
}

Beginner Error with "getline"

3 Answers3