why do I get warning in this C code using fprintf?

Question

fprintf(pFile,msg.c_str());

why do I get a warning in Xcode :

Format string is not a string literal (potentially insecure)

I assume I get this warning to prevent attacks were msg contains some thing like %s which stream the stack to the screen until it gets to null termination. Is there any safe way to use fprintf in this case?

Answer 1

You can either give a format string,

fprintf(pFile, "%s", msg.c_str());

or use fputs,

fputs(msg.c_str(), pFile);