I want to see if a character is present in a string.

views:

150

answers:

+3 Q:

I want to see if a character is present in a string.

Hi,

I'm programming a program in C++ (typical game) in which you need to guess a letter and it will check if it is present in a string.

For example

Secret String: I like to program.

Guess1: 'a'

Display: . .... .. .....a...

Etc.

But i don't know how to see if a character is in this secret string.

I'm using std::string (obligatory)

Any help is appreciated!

+7 A:

You can use find_first_of

JRL 2010-07-21 15:08:12

You can, but it's not really intended for this job. It's intended to find any one of a set of characters.

Jerry Coffin 2010-07-21 15:10:52

The function is also overloaded to take only one character

Tomaka17 2010-07-21 15:11:53

Not to mention that said set of characters could very well consist of a single character anyway. Using `string::find` would make your code slightly more concise, though, as the difference in functionality with `string::find_first_of` is irrelevant in this case.

JAB 2010-07-21 15:12:46

@Jerry: not true and hardly worth a downvote, especially since there is the method signature `size_t find_first_of ( char c, size_t pos = 0 ) const;`

JRL 2010-07-21 15:14:12

Yes, it is true. Yes, it's overloaded to take a single character, and yes, you can also pass a string that only contains one character (which is what the single-character version does, indirectly). Nonetheless, using "first_first_of" when you do *not* intend to find the first one of a set of characters is misleading at best, and a poor idea. When writing code, understanding by other people is primary, and by the compiler secondary (or *should* be anyway).

Jerry Coffin 2010-07-21 15:23:18

@Amardeep: Given the question, the right (or at least best) answer is clearly `find`, not `find_first_of`. The subsequent discussion has shown only how the answer is poor rather than dead wrong -- hardly a good reason for an up-vote.

Jerry Coffin 2010-07-21 16:41:19

@Jerry: We obviously have different criteria for voting. I only downvote if the answer is factually wrong or materially harms the knowledge base. I'll revoke it if the breach is corrected. I'll upvote if the answer offered something useful even when that useful thing may not be 100% germane to the original question. I feel that comments are a better mechanism to steer answers that are functionally correct but not optimal. I'm not preaching that you do the same but explaining why I did.

Amardeep 2010-07-21 17:11:19

@Amardeep: apparently we do. I think anything further about it belongs on meta, not here though...

Jerry Coffin 2010-07-21 17:40:49

+4 A:

There are several methods in std::string that would help:

find() rfind() find_first_of() find_last_of() substr()

Amardeep 2010-07-21 15:09:06

+9 A:

Begin by learning searching in a documentation like : http://www.cplusplus.com/reference/string/string/ . (Hint : you want to "find" something ... )

Scharron 2010-07-21 15:09:39

+1 because you offered documentation instead of pointing to the exact answer to this obvious homework question.

paercebal 2010-07-21 15:24:09

@paercebal: How do you know it's not just a hobbyist learning to write a game program? Most homework assignments have tended to use char arrays and disallow library functions. Besides, you don't provide them the whole game just by telling them which function finds a character in a string. (Oh, +1 for the documentation).

Amardeep 2010-07-21 15:32:29

@Amardeep : The way the question is formulated, the question itself, and some hints like "I'm using std::string (**obligatory**)". cpluplus.com is a very good C++ reference, and the author of the answer both pointed to it and gave a hint... ^_^ ...

paercebal 2010-07-22 08:13:31

+1 A:

Take a look at string::find

JLWarlow 2010-07-21 15:09:47

Thx all, just really overlooked it :s

2010-07-26 08:22:12

ansaurus

tags:

views:

answers:

I want to see if a character is present in a string.

related questions