Comparing const char to a string

Question

I have an issue comparing a const char to a string... If I use Com_Printf ("%s", value); It returns what I want (0.3c), but how can I convert value to a string and compare that to 0.3c? This is what I have:

value = SearchInfostring(msg, "shortversion");
if (value != "0.3c")
{
    Com_Printf (MSG_WARNING,
            Com_Printf (MSG_WARNING,
                "> WARNING: Value: Should be 0.3c, is:  %s \n",
                value);
//Run stuff
}

That returns: WARNING: Value: Should be 0.3c, is: 0.3c

I assume value is std::string as you wrote. Are you sure there are no trailing/leading spaces in value? — Rafal R
– Rafal R, Commented Apr 22, 2012 at 19:30

Bojan Komazec · Accepted Answer · 2012-04-22 19:29:58Z

10

If value is of type const char*, expression

value != "0.3c"

is comparing two pointers (addresses), not strings. You want to compare string and a string literal so can use strcmp:

if(strcmp(value, "0.3c"))
{
   // strings are not equal
}
else
{
   // strings are equal
}

Bear in mind that preferred string type in C++ is std::string.

answered Apr 22, 2012 at 19:29

Bojan Komazec

9,6162 gold badges44 silver badges52 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bojan Komazec Over a year ago

I'm glad it helped. Note that if value was of type std::string the code you posted would be working as you expected (as chris posted in his answer).

Qaz · Accepted Answer · 2012-04-22 19:28:34Z

3

Use an std::string for value.

std::string value = SearchInfoString(msg, "shortversion");

Then, you can compare it normally. If you cannot use a string at all for whatever reason (the return value can be converted), use strcmp.

if (strcmp (value, "0.3c") != 0)
{
    ...
}

answered Apr 22, 2012 at 19:28

Qaz

62.3k14 gold badges149 silver badges210 bronze badges

Comments

Eric Melski · Accepted Answer · 2012-04-22 19:29:15Z

0

It seems that SearchInfoString returns a char *, based on the way you use it with Com_Printf. Therefore you can just use strcmp() to compare value to "0.3c". For example:

if (strcmp(value, "0.3c") != 0)
{
    // Print warning
}

answered Apr 22, 2012 at 19:29

Eric Melski

16.9k3 gold badges40 silver badges54 bronze badges

Collectives™ on Stack Overflow

Comparing const char to a string

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related