Getline Not Asking For Input

getline not asking for input?

You have to be careful when mixing operator>> with getline. The problem is, when you use operator>>, the user enters their data, then presses the enter key, which puts a newline character into the input buffer. Since operator>> is whitespace delimited, the newline character is not put into the variable, and it stays in the input buffer. Then, when you call getline, a newline character is the only thing it's looking for. Since that's the first thing in the buffer, it finds what it's looking for right away, and never needs to prompt the user.

Fix:
If you're going to call getline after you use operator>>, call ignore in between, or do something else to get rid of that newline character, perhaps a dummy call to getline.

Another option, and this is along the lines of what Martin was talking about, is to not use operator>> at all, and only use getline, then convert your strings to whatever datatype you need. This has a side effect of making your code more safe and robust. I would first write a function like this:

int getInt(std::istream & is)
{
    std::string input;
    std::getline(is,input);

    // C++11 version
    return stoi(input); // throws on failure

    // C++98 version
    /*
    std::istringstream iss(input);
    int i;
    if (!(iss >> i)) {
        // handle error somehow
    }
    return i;
    */
}

You can create a similar function for floats, doubles and other things. Then when you need in int, instead of this:

cin >> i;

You do this:

i = getInt(cin);

std::getline not re-requesting user input in while loop

In the first iteration of the loop:

cin >> quit;

will read up to, but not including the newline character.

In the second iteration of the loop:

std::getline(std::cin, input);

will read that newline character, and hence read an empty string into input.

There are several ways to fix this

1. You could use getline to read the string quit

2. You could read input again, if it happens to be an empty string.

3. You could call cin.get(); after the cin >> quit to clear the newline.

c++ getline() isn't waiting for input from console when called multiple times

The problem is you are mixing calls to getline() with the use of the operator >>.

Remember that operator >> ignored leading white space so will correctly continue across lines boundaries. But stops reading after the input has successfully been retrieved and thus will not swallow trailing '\n' characters. Thus if you use a getline() after a >> you usually get the wrong thing unless you are careful (to first remove the '\n' character that was not read).

The trick is to not use both types of input. Pick the appropriate one and stick to it.

If it is all numbers (or objects that play nice with operator >>) then just use operator >> (Note string is the only fundamental type that is not symmetric with input/output (ie does not play nicely)).

If the input contains strings or a combination of stuff that will require getline() then only use getline() and parse the number out of the string.

std::getline(std::cin, line);
std::stringstream  linestream(line);

int  value;
linestream >> value;

// Or if you have boost:
std::getline(std::cin, line);
int  value = boost::lexical_cast<int>(line);

cin.getline not waiting for input and setting parameters on rand

This is a common problem of reading string input after an int/long/float/etc. The issue is the '\n' character remaining in the buffer after an integer has been read:

cin >> maximumSnowfall;

When you call getline the '\n' still remaining in the buffer gets read right away. The standard library interprets it as an empty string, and returns right away.

To avoid this issue call ignore after reading an int:

cin >> maximumSnowfall;
cin.ignore(1, '\n');

getline prompt gets skipped, not working as intended

cin >> age1; does not read the newline character following the number. The newline remains in the input buffer, then prematurely stops the second getline.

So, your program already works as long as you enter the first age and the second name on the same line.

One solution would be to skip whitespace after the numbers:

cin >> age1 >> ws;

Live demo.

getline not working properly ? What could be the reasons?

Since you have not posted any code. I am going to take a guess.

A common problem while using getline with cin is getline does not ignore leading whitespace characters.

If getline is used after cin >>, the getline() sees this newline character as leading whitespace, and it just stops reading any further.

How to resolve it?

Call cin.ignore() before calling getline()

Or

make a dummy call getline() to consume the trailing newline character from the cin >>

std::getline input not working properly in C++

Following on from Prince John Wesley's reply, try

    cin >> num >> endl;

to flush the stream buffer before using it again.

c++ getline doesn't get the input

You need to consume the newline character.

int main(){
    string a, b;
    int n1, n2;

    getline(cin, a);

    cin >> n1;
    cin.get(); // this will consume the newline
    getline(cin, b);

    cin >> n2;
    cin.get(); // this will consume the newline
}

std::getline will consume the newline for you.

Here's example usage:

21:42 $ cat test.cc 
#include <iostream>
#include <string>

using namespace std;

int main(){
    string a, b;
    int n1, n2;

    getline(cin, a);

    cin >> n1;
    cin.get(); // this will consume the newline
    getline(cin, b);

    cin >> n2;
    cin.get(); // this will consume the newline

    std::cout << a << " " << b << " " << n1 << n2 << std::endl;
}
✔ ~ 
21:42 $ g++ test.cc
✔ ~ 
21:42 $ ./a.out 
hello
4
world
2
hello world 42

getline statement is not getting the input

cin will leave new lines in the buffer. Therefore when you get rno from cin there is actually an \n left in the cin buffer. When you go to read the name it just grabs the \n and instantly returns.
Doing something like cin.ignore(); after the first cin should clear the buffer and allow you to correctly read the user input.

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