I'm trying to print a string the following way:
int main(){ string s("bla"); printf("%s \n", s); ....... } but all I get is this random gibberish.
Can you please explain why?
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4 Answers
Because %s indicates a char*, not a std::string. Use s.c_str() or better still use, iostreams:
#include <iostream> #include <string> using namespace std; int main() { string s("bla"); std::cout << s << "\n"; } 
3 Comments
user429400
I've tried it with std::cout and the compiler issues an error: binary '<<' : no operator found which takes a right-hand operand of type 'std::string'
pjc50
That's very strange. Which C++ implementation is this?
Marcelo Cantos
I've amended the code to be self-contained and compilable (and tested).
You need to use c_str to get c-string equivalent to the string content as printf does not know how to print a string object.
string s("bla"); printf("%s \n", s.c_str()); Instead you can just do:
string s("bla"); std::cout<<s; 
4 Comments
user429400
Thank... btw - why? printf does not know how to handle strings? Is there another method I can use?
user429400
I've tried it with std::cout and the compiler issues an error: binary '<<' : no operator found which takes a right-hand operand of type 'std::string'
Roman A. Taycher
printf does not know how to handle c++ std::string s, it works on c strings(array of char with \0 to mark the end of string), note that because of backwards compatibility c++ c++ string literals, ie just "bla" instead of string s("bla") are c strings and not objects of the c++ std::string class.
user429400
Oh, Ok, it makes sense:) Thank you.
I've managed to print the string using "cout" when I switched from :
#include <string.h> to
#include <string> I wish I would understand why it matters...
3 Comments
Cedric H.
From
include to include ? What do you mean ?
bk1e
The answer source included the data that Markdown removed. (BTW, @lazygoldenpanda, please don't post answers for things that should be comments or edits to the original question.)
Digikata
string.h is a standard C header. Headers for most C++ standard library items don't have a .h To access standard C headers in C++ code you should prefix a 'c'. e.g. <cstdlib> instead of <stdlib.h>. This is the intent of the C++ standards body to try to keep things non-colliding between C and C++.
