std::cin is the global stream object provided by the C++ standard library for reading from the standard input stream.
For more general questions about std::istream use the iostream or istream tags.
Questions tagged [cin]
1859 questions
215
votes
8 answers
std::cin input with spaces?
#include
std::string input;
std::cin >> input;
The user wants to enter "Hello World". But cin fails at the space between the two words. How can I make cin take in the whole of Hello World?
I'm actually doing this with structs and…
dukevin
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133
votes
14 answers
120
votes
4 answers
Why would we call cin.clear() and cin.ignore() after reading input?
Google Code University's C++ tutorial used to have this code:
// Description: Illustrate the use of cin to get input
// and how to recover from errors.
#include
using namespace std;
int main()
{
int input_var = 0;
// Enter the do…
JacKeown
- 2,780
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96
votes
7 answers
When and why do I need to use cin.ignore() in C++?
I wrote a very basic program in C++ which asked the user to input a number and then a string. To my surprise, when running the program it never stopped to ask for the string. It just skipped over it. After doing some reading on StackOverflow, I…
Raddicus
- 1,114
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- 9
83
votes
6 answers
How do I deal with the max macro in windows.h colliding with max in std?
So I was trying to get valid integer input from cin, and used an answer to this question.
It recommended:
#include // includes WinDef.h which defines min() max()
#include
using std::cin;
using std::cout;
void Foo()
{
int…
Almo
- 15,538
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64
votes
22 answers
How to cin values into a vector
I'm trying to ask the user to enter numbers that will be pushed into a vector,
then using a function call to count these numbers.
why is this not working? I'm only able to count the first number.
template
void write_vector(const…
Sean
- 957
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62
votes
9 answers
if (cin >> x) - Why can you use that condition?
I have been using "Accelerated C++" to learn C++ over the summer, and there's a concept which I don't seem to understand properly.
Why is
int x;
if (cin >> x){}
equivalent to
cin >> x;
if (cin){}
By looking at the code, it seems to me that we're…
Muhsin Ali
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56
votes
2 answers
Why does stringstream >> change value of target on failure?
From Stroustrup's TC++PL, 3rd Edition, Section 21.3.3:
If we try to read into a variable v and the operation fails, the value of v should be unchanged (it is unchanged if v is one of the types handled by istream or ostream member functions).
The…
user1823664
- 1,071
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52
votes
4 answers
changing the delimiter for cin (c++)
I've redirected "cin" to read from a file stream cin.rdbug(inF.rdbug())
When I use the extraction operator it reads until it reaches a white space character.
Is it possible to use another delimiter? I went through the api in cplusplus.com, but…
yotamoo
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50
votes
4 answers
cin and getline skipping input
earlier i posted a question about cin skipping input, and I got results to flush, and use istringstream, but now I tried every possible solution but none of them work.
here is my code:
void createNewCustomer () {
string name, address;
cout…
hakuna matata
- 3,243
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49
votes
13 answers
Using getline(cin, s) after cin
I need the following program to take the entire line of user input and put it into string names:
cout << "Enter the number: ";
int number;
cin >> number;
cout << "Enter names: ";
string names;
getline(cin, names);
With the cin >> number command…
pauliwago
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46
votes
3 answers
cin.ignore(numeric_limits::max(), '\n')
What does cin.ignore(numeric_limits::max(), '\n') mean in C++?
Does it actually ignore the last input from the user?
Zyi
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44
votes
3 answers
Multiple inputs on one line
I have looked to no avail, and I'm afraid that it might be such a simple question that nobody dares ask it.
Can one input multiple things from standard input in one line? I mean this:
float a, b;
char c;
// It is safe to assume a, b, c will be in…
Joshua
- 4,270
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43
votes
5 answers
std::cin.getline( ) vs. std::cin
When should std::cin.getline() be used? What does it differ from std::cin?
Simplicity
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42
votes
4 answers
C++: how do I check if the cin buffer is empty?
How do you check to see if the user didn't input anything at a cin command and simply pressed enter?
Matt Shindala
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