I'm getting warnings when I compile something like this...
std::string something = "bacon";
sprintf("I love %s a lot", something.c_str());
Where it says "warning: deprecated conversion from string constant to 'char *'. I tried converting the text to be...
const char *
instead but I get a different error. I'm not committed to sprintf if there is a better option.
For sprintf to work, you need to provide an array of char big enough to write the result to as the first argument.
However, you can (and should!) just use the far easier operator+ for C++ strings:
std::string res = "I love " + something + " a lot";
sprintf("I love %s a lot", something.c_str);
In that code, you should call something.c_str() with proper function call () syntax.
Note also that the above use of sprintf() is wrong, since you didn't provide a valid destination string buffer for the resulting formatted string.
Moreover, for security reasons, you should use the safer snprintf() instead of sprintf(). In fact, with snprintf() you can specify the size of the destination buffer, to avoid buffer overruns.
The following compilable code is an example of snprintf() usage:
#include <stdio.h>
#include <string>
int main()
{
std::string something = "bacon";
char buf[128];
snprintf(buf, sizeof(buf), "I love %s a lot", something.c_str());
printf("%s\n", buf);
}
P.S.
In general, in C++ you may consider string concatenation using std::string::operator+, e.g.:
std::string result = "I love " + something + " a lot";
snprintf() is standard; sprintf_s() is Microsoft-specific. I think snprintf() has been implemented in Visual C++ since VS2015.It doesn't look like a correct use of sprintf. First parameter is supposed to be a char * with already a backing memory. For example:
char *str = malloc (BUFSIZ);
sprintf (str, "I love %s a lot", something.c_str);
c_str() needs to be a function call.
malloc in C++. Use new unless you absolutely need to use malloc(normally interfacing with a C api).
sprintfbe a buffer for the result?.c_str()not.c_str(which is how I know this isn't your real code).something.c_str()as a function.