CJson - Insert missing quotes around strings

Question

I have a text file of format given below (this is just sample file, but actually file is big one with key, values). Some of the values for the key will have format in file (look for value of Port key in below file). This is input file for me.

I am converting this file into Json using CJson Library in C++. Since value corresponding to Port key is not a valid string or value, CJson gives error message saying "Insert missing quotes around strings". So I tried to convert Port value to string using below code. But I am unable to insert missing quotes around. Could you please help me how to "Insert missing quotes around strings".

Code I tried:

ifstream infile { "conf_file.conf" };
string file_contents{ istreambuf_iterator<char>(infile), istreambuf_iterator<char>() };
pParentJson = cJSON_Parse( (char*)file_contents.c_str() );
cJSON* pJsonObj = cJSON_GetObjectItem(pParentJson,"port");
char* pDataBuffer = cJSON_Print(pJsonObj);
cout<<pDataBuffer<<endl;

Text File

{
"port": <CbTcpPortVariable>
"IP" : "127.0.0.1"
"Message": "Hello"
}