What's the C++ version of scanf?

Question

For example...

char* foo;
scanf("%[^\n\r]", foo);

How can I do this in C++, without including C libraries?

score 3 · Answer 1 · answered Jun 20 '15 at 01:25

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The equivalent to what you have posted [aside from the fact that char *foo without an allocation of memory, probably will lead to writing to either NULL or some random location in memory] would be

 std::string foo;
 std::getline(std::cin, foo);

But for more complex cases, where you read multiple items, either cin >> x >> y >> z; or std::getline(std::cin, str); std::stringstream ss(str); ss >> x >> y >> z; - or some combination thereof.

But C-code that is valid is valid in C++ too. It's not always the "right" solution, but certainly not completely wrong either.

answered Jun 20 '15 at 01:25

Mats Petersson

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When parsing input using a `std::stringstream`, you should use `std::istreamstream` instead. – Remy Lebeau Jun 20 '15 at 02:11
@BenVoigt: C++98, the same version that standardized the STL. – Remy Lebeau Jun 20 '15 at 03:19
@BenVoigt: `std::istringstream` is a typedef for `std::basic_istringstream`. See C++98 (ISO/IEC 14882:1998) §27.7.2, "Template class basic_istreamstream". – Remy Lebeau Jun 20 '15 at 04:06
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/81051/discussion-between-remy-lebeau-and-ben-voigt). – Remy Lebeau Jun 20 '15 at 06:09
@Remy: I've just been dropping hints about the typo in your first comment. – Ben Voigt Jun 20 '15 at 06:38
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@BenVoigt: I would have appreciated it if you had just said so up front and not wasted my time looking up the references for you. Oh well. – Remy Lebeau Jun 20 '15 at 06:51
@RemyLebeau: Classic Ben. – Lightness Races in Orbit Apr 28 '17 at 13:35

score 2 · Answer 2 · answered Jun 20 '15 at 01:03

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The C++ version of scanf is std::scanf and can be found in the <cstdio> header. Yes, it's the same function - because C functions can also be used in C++.

answered Jun 20 '15 at 01:03

Barry

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Yes and printf also can be used in C++...but nobody uses it. I'm just asking if there's another way to do this --'...without using c libraries. – Felipe Endlich Jun 20 '15 at 01:05
You are probably going to end up [even if you don't do it yourself] include some "c" libraries whatever you do. – Mats Petersson Jun 20 '15 at 01:19

score 0 · Answer 3 · edited Jun 20 '15 at 02:12

0

There are two simple methods to replace scanf.

std::cin which can be found in the standard library.
std::getline(std::cin, line); which takes user's input, up to but not including the line break, into a std::string variable line.

edited Jun 20 '15 at 02:12

Remy Lebeau

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answered Jun 20 '15 at 01:40

Dian Sheng

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What's the C++ version of scanf?

3 Answers3