Cannot convert ‘std::string’ to ‘const char*

Question

Hi can any one tell what wrong with this code ?.

 string s=getString(); //return string

    if(!strcmp(s,"STRING")){
         //Do something
    }

while compiling I am getting the error like

error: cannot convert ‘std::string’ to ‘const char*’ for argument ‘1’ to ‘int strcmp(const char*, const char*)’|

Answer 1

strcmp accepts const char* as argument. You can use c_str method:

if(!strcmp(s.c_str(),"STRING"))

Or just use overloaded operator== for std::string:

if(s == "STRING")

Answer 2

You need to use s.c_str() to get the C string version of a std::string, along the lines of:

if (!strcmp (s.c_str(), "STRING")) ...

but I'm not sure why you wouldn't just use:

if (s == "STRING") ...

which is a lot more readable.

Answer 3

You can use the c_str() method on std::string as in the other answers.

You can also just do this:

if (s == "STRING") { ... }

Which is clearer and doesn't pretend that you're writing C.

Answer 4

You must use c_str() and it should solve your problem.