compare char* with each other

Question

I currently have a method called getResult which returns const char* now I am doing something like this

if(getResult=="Something")
{
  ...
}

However it seems this type of comparison doesn't work. Isn't "Something" also a const char pointer ? or in this case are the addresses being compared?

@Rapptz thanks that works. Could you post why my way was not working so that I could close this question. — Casper_2211, Feb 09 '13 at 00:07
Because you can't compare const char* strings with `operator==`. Other answers explain this too. — Rapptz, Feb 09 '13 at 00:08

score 6 · Answer 1 · answered Feb 09 '13 at 00:06

6

Yes, the addresses are being compared. To compare the contents of two strings, use the strcmp function:

if (strcmp(getResult, "Something") == 0) {
    ...
}

answered Feb 09 '13 at 00:06

score 5 · Accepted Answer · answered Feb 09 '13 at 00:06

If getResult is a method (member function) you need to call it to compare the result, so you probably want:

if (something.getResult() == std::string("Something"))
  // ...

If, on the other hand, getResult is really a pointer to char (or pointer to const char), you need to convert one of the things you're comparing to string before the comparison):

if (getResult == std::string("Something"))

or:

if (std::string(getResult) == "something))

IMO, this should almost never be necessary -- instead of starting with a pointer to [const] char, then converting, you should normally use std::string throughout.

score 2 · Answer 3 · answered Feb 09 '13 at 00:08

2

If you compare 2 string constants in C/C++ you compare the actual address of each string, not the content. Using strcmp on 2 c-strings or using C++'s std::string class will compare the content.

answered Feb 09 '13 at 00:08

bash0r

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compare char* with each other

3 Answers3