I have some error can anyone help me in this

Question

error: incompatible types in assignment of 'std::__cxx11::string' {aka'std::__cxx11::basic_string<char>'} to 'char [100]'
error: cannot convert 'std::__cxx11::string' {aka 'std::__cxx11::basic_string<char>'} to 'const char*'

and I got the above two errors for these lines of codes

    string s1=asctime(localtime(&timetoday));;
    string r=s1.substr(4,6);
    ch=r;                        //char ch[100];(defined aleady)
    //1st error was in line just above this comment
    if(strcmp(r,"Dec 20")==0)
 //2nd error was in line just above this comment
    {
        cout<<"made my first try for creating this program";
    }
    else if(strcmp(r,"Dec 21")==0)
    {
        cout<<"Shortest day of the year";
    }

I'm trying to create a simple remainder program in C++ using code blocks.

may be from this line `ch = r;` , looks like you are mixing `C`and `C++`. `r` is `string` and `ch` is a `char` — IrAM, Dec 21 '20 at 06:27
`string`s have their own built-in comparison operators. Where possible go all in on `string` and use `string`s facilities. — user4581301, Dec 21 '20 at 06:31
Please don't add unrelated language tags. This question is about C++ with C++ code, so don't tag C. — Some programmer dude, Dec 21 '20 at 06:31
As for your problem, get [some good books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) and take some classes to learn C++ *properly*. — Some programmer dude, Dec 21 '20 at 06:32

Andreas Wenzel · Answer 1 · 2020-12-21T07:07:12.420

The problem is in the following line:

ch = r;

The variable ch is of type char[100], the variable r is of type std::string. These types are not compatible, you cannot assign an std::string to a char array.

You probably want to write the following instead:

strcpy( ch, r.c_str() );

However, it would be simpler not to use C-style strings at all, and instead use std::string everywhere, like this:

string s1=asctime(localtime(&timetoday));;
string r=s1.substr(4,6);
if( r == "Dec 20" )
{
    cout<<"made my first try for creating this program";
}
else if( r == "Dec 21" )
{
    cout<<"Shortest day of the year";
}

Another mistake in your program seems to be that you are calling strcmp twice, once like this:

strcmp(r,"Dec 20")

And once like this:

strcmp(ch,"Dec 21")

The second one is correct, but the first one is wrong, as you must pass a C-style string (a char array), and not a C++ style string (a std::string). You probably meant to write ch instead of r. Alternatively, if you want to keep using r, you can write r.c_str() instead, which will return a C-style string. But, as already stated above, the best solution would probably be to use std::string everywhere and not use strcmp at all, as it is only intended for C-style strings.

THANK YOU SIR/MADAM YOU SOLVED MY 1st ERROR. THANK YOU I CORRECTED MY MISTAKE. — RB Editz, Dec 21 '20 at 06:42

score 1 · Answer 2 · answered Dec 21 '20 at 06:30

1

The code is incomplete, i.e. ch is not defined, but you probably want to use r.c_str() in the first call to strcmp, and in the 2nd case r.c_str() instead of ch.

answered Dec 21 '20 at 06:30

Allan Wind

23,068
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score 0 · Answer 3 · answered Dec 21 '20 at 06:31

0

strcmp compares two cstrings(const char*), you are passing a std::string. try something like ``if(r == "Dec 20") ...```

answered Dec 21 '20 at 06:31

Tigermouthbear

11
3

THANK YOU SIR/MADAM YOU SOLVED MY 2nd ERROR. THANK YOU I CORRECTED MY MISTAKE. – RB Editz Dec 21 '20 at 06:42

score 0 · Answer 4 · answered Dec 21 '20 at 06:32

0

ch = r you are mixing string with char array or c with cpp . Why not make your life easy you can use std::copy in this way

 std::copy(r.begin(),r.end(),ch);

Happy Coding.

answered Dec 21 '20 at 06:32

Umar Farooq

418
2
14

score 0 · Answer 5 · edited Dec 11 '21 at 07:26

0

The variable ch is of kind char[100], the variable r is of kind std::string. These sorts are not compatible, you can not assign an std::string to a char array

edited Dec 11 '21 at 07:26

Amila Senadheera

12,229
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answered Dec 10 '21 at 23:55

omar KDB

21
2

This answer adds nothing new to the answers already posted. – zkoza Dec 12 '21 at 19:56

I have some error can anyone help me in this

5 Answers5