C++ Using strcmp() in Class on Private Member Data

Question

I'm doing an assignment for class and am having problems compiling this code. I have used #include <string> in both the main .cpp file and the class .cpp file. The error is "'strcmp' is not a member of 'std'" but I get it whether I use std::strcmp() or strcmp().

Any thoughts on what I am doing wrong?

double temporary::manipulate()
{
    if(!std::strcmp(description, "rectangle"))
    {
    cout << "Strings compare the same." << endl;
        return first * second;
    }
    return -1;
}

Answer 1

You need to include <string.h> or <cstring> for strcmp or std::strcmp respectively. <string> is a C++ standard library required for std:string and other related functions.

Note that std::strcmp expects two const char* , not an std::string . If description is an std::string , you can get a pointer to the underlying data with the c_str() method:

if(!std::strcmp(description.c_str(), "rectangle"))

or just use the comparison operator. This is the more idiomatic solution:

if(description == "rectangle")

Answer 2

#include <cstring>即可使用此功能。

Answer 3

Standard C functions including strcmp in C++ are declared in header <cstring> . Header <string> defines standard class std::basic_string . So you need directive

#include <cstring>

Answer 4

Try

#include <cstring>

...

    if(!std::strcmp(description.c_str(), "rectangle"))