#include <iostream>
#include <string.h>
using namespace std;
int main ()
{
string st = "Hello world";
return 0;
}
and
#include <string>
int main ()
{
std::string st = "Hello world";
return 0;
}
I tried compiling this code using minGW compiler on netbeans. It brings up the following error after the successful build.
RUN FAILED (exit value -1,073,741,511, total time: 93ms)
But it works clean when strings are not used. I would like to know what I am doing wrong here. Thanks in advance.
Use c++ strings and don't use using namespace std:
#include <string> //c++ string header
int main ()
{
std::string st = "Hello world";
return 0;
}
#include <string.h> is the old C-style string header and most likely isn't what you want to use here. See this question for more details: Difference between <string> and <string.h>?
Note: If you really wanted the old C-style strings then you really should be using #include <cstring> because this will put those functions into the std namespace and won't cause any namespace pollution that can lead to other undesirable outcomes.
Likely what happened was that you used the old style string header and didn't properly initialize those strings. The old C-style strings don't have a constructor and operator= defined like the std::string class.
Edit: After looking at the Netbeans forum this is a problem with Netbeans and not a c++ issue. Try changing the output to an external terminal in Netbeans. Or run the program directly from the command line. If these approaches don't fix the problem or are undesirable then make a post over on the Netbeans forum. Also have a look at this question: Program won't run in NetBeans, but runs on the command line!
Uss #include <string> instead of string.h
Related
I've been puzzled by this for a while. To test this out, I made a simple program that just creates a std::string variable and prints it out to the screen. However, it doesn't include <string.h>.
#include <iostream>
using namespace std;
int main()
{
string name = "Test";
cout << name << endl;
return 0;
}
What confuses me is that this program compiles and runs perfectly. Right now I'm using the clang compiler that came with the XCode Developer Tools. Is this intended behavior? I hope this question isn't too ridiculous since I just started learning C++.
The reason you do not need to include the #include <string.h> header file is because when you include the #include <iostream> header file it includes std::string.
However, do not rely on it. What may work on your compiler may not work on another. Always include the proper header files.
To edit your example this is how you should use it:
#include <iostream>
#include <string>
int main()
{
std::string name = "Test";
std::cout << name << std::endl;
return 0;
}
Also note: why you should not use using namespace std;.
Why does my program compile successfully if I don't include <string.h>?
Because you don't use any definition / declaration from <string.h>.
program compiles and runs perfectly ... Is this intended behavior?
It is incidental behaviour.
There are no guarantees that one standard header wouldn't include other standard headers. It just so happens that <iostream> included <string> in this particular version of the standard library. Since there is no guarantee for this, it would be a mistake to rely on such transitive inclusion.
I am trying to take a string and parse it into an int. I have read the many answers out there, and it seems that using stoi is the most up-to-date way. It appears to me that stoi uses std, but I am getting Function 'stoi' could not be resolved despitre using namespace std;
#include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include<stdlib.h>
using namespace std;
int main(int argc, char* argv[]) {
string line = "";
string five = "5";
int number = stoi(five); //Error here with stoi
return 0;
}
Any ideas what is causing this?
Update:
I am using Eclipse. My flags are: -c -fmessage-length=0 -std=c++11
If you are using GCC or MINGW, then this is the answer:
std::stoi doesn't exist in g++ 4.6.1 on MinGW
This is a result of a non-standard declaration of vswprintf on
Windows. The GNU Standard Library defines
_GLIBCXX_HAVE_BROKEN_VSWPRINTF on this platform, which in turn disables the conversion functions you're attempting to use. You can
read more about this issue and macro here:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37522.
If you're willing to modify the header files distributed with MinGW,
you may be able to work around this by removing the
!defined(_GLIBCXX_HAVE_BROKEN_VSWPRINTF) macro on line 2754 of
.../lib/gcc/mingw32/4.6.1/include/c++/bits/basic_string.h, and adding
it back around lines 2905 to 2965 (the lines that reference
std::vswprintf). You won't be able to use the std::to_wstring
functions, but many of the other conversion functions should be
available.
Please always provide platform and compiler information.
Toggle on C++11 support in your compiler flags. -std=c++11 for a recent gcc. For Eclipse, please refer to the corresponding question in the FAQ and this answer explains how to get rid of the remaining Eclipse warning.
If you are amenable to parsing an int another way, how about using an STL algorithm and a C++11 lambda expression?
#include <algorithm>
#include <iostream>
#include <string>
using namespace std;
int main() {
string str = "12345";
int num = 0;
for_each(str.begin(), str.end(), [&num](char c){ num = 10 * num + (c - '0'); });
cout << str << " = " << num << endl;
}
Hi I am new to C++ and Code::Block
I am trying to make a simple code to test it, using strings.
when I compile the code there is no problem, but when I try to debug it, Code::Block gives me the following warning:
Cannot open file:
File:../../../../../src/gcc-4.9.2/libgcc/unwind-sjlj.c
Info: "Multiple information windows with the same message have been
supressed."
Image of the error FYI:
Part of the code that gives me an error.
inside main function
#include <iostream>
#include <string>
int main ()
{
std::mystring("What's wrong with strings");
return 0;
}
I realise that this error only occurs when I try to debug a string or a file containing a string.
Any help would be appreciated.
some other information that might help:
Code::Block 16.01
Compiler MinGW gcc4.9.2
Windows 7 Professional 32 bits SP1
First of all, to use strings you must include the file header string. And the name of the type string is..std::string, not std::mystring.
#include <string>
int main(int argc, char** argv)
{
std::string mystring("Nothing's wrong with strings");
return 0;
}
#include <iostream>
using namespace std;
int main ()
{
string mystring = "Whats wrong with my string";
return 0;
}
If you write it in the following way, it should work.
It's safer to define strings like I showed it. It will be also easier for you if you add using namespace std in the beginning of every program if you are new to C++.
I am trying to take a string and parse it into an int. I have read the many answers out there, and it seems that using stoi is the most up-to-date way. It appears to me that stoi uses std, but I am getting Function 'stoi' could not be resolved despitre using namespace std;
#include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include<stdlib.h>
using namespace std;
int main(int argc, char* argv[]) {
string line = "";
string five = "5";
int number = stoi(five); //Error here with stoi
return 0;
}
Any ideas what is causing this?
Update:
I am using Eclipse. My flags are: -c -fmessage-length=0 -std=c++11
If you are using GCC or MINGW, then this is the answer:
std::stoi doesn't exist in g++ 4.6.1 on MinGW
This is a result of a non-standard declaration of vswprintf on
Windows. The GNU Standard Library defines
_GLIBCXX_HAVE_BROKEN_VSWPRINTF on this platform, which in turn disables the conversion functions you're attempting to use. You can
read more about this issue and macro here:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37522.
If you're willing to modify the header files distributed with MinGW,
you may be able to work around this by removing the
!defined(_GLIBCXX_HAVE_BROKEN_VSWPRINTF) macro on line 2754 of
.../lib/gcc/mingw32/4.6.1/include/c++/bits/basic_string.h, and adding
it back around lines 2905 to 2965 (the lines that reference
std::vswprintf). You won't be able to use the std::to_wstring
functions, but many of the other conversion functions should be
available.
Please always provide platform and compiler information.
Toggle on C++11 support in your compiler flags. -std=c++11 for a recent gcc. For Eclipse, please refer to the corresponding question in the FAQ and this answer explains how to get rid of the remaining Eclipse warning.
If you are amenable to parsing an int another way, how about using an STL algorithm and a C++11 lambda expression?
#include <algorithm>
#include <iostream>
#include <string>
using namespace std;
int main() {
string str = "12345";
int num = 0;
for_each(str.begin(), str.end(), [&num](char c){ num = 10 * num + (c - '0'); });
cout << str << " = " << num << endl;
}
I have been trying to debug this problem for a while and quite honestly, I just can't see what I'm doing wrong.
Why is there a syntax error?
#include <iostream>;
#include <time.h>;
#include <stdio.h>;
#include <stdlib.h>;
using namespace std;
class Problem3 {
public:
bool isPrime(long double num) {
srand(time(NULL));
return 0;
}
};
The error I'm getting is,
"Function 'srand' could not be resolved."
I'm well aware now that I don't need the semi-colons after 'include' statements
I'm using Eclipse CDT along with MinGW as my compiler
How I resolved the problem:
It had to do with the MinGW compiler I was using. Switching over to Visual Studio solved the problem.
; at the end of the #include directives are the problem in your code. #include directives don't need (wrong to place indeed) semicolons at the end unlike C++ statements.
[Warning] extra tokens at end of #include directive [enabled by default]
It seems any character after > in the directive causes this error/warning.
#include<iostream>a //error
Change to this:
#include <iostream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
class Problem3 {
public:
bool isPrime(long double num) {
srand(time(NULL));
return 0;
}
};
int main(){
cout<<"Hello Main";
}
EDIT:
Regarding the linker issue:
One suggestion is C++ expects types to be explicitly casted between types (more than C). So, use a cast to convert time_t which is returned by the time to unsigned int which is the input parameter type of srand. (And of course this might not be the problem with linker error)
Instead of using stdlib.h, try using <cstdlib>, try if it helps. Because it uses namespace.
Apart from that, I have seen this snippet here. Use that pattern if it helps.
#include <cstdlib>
#include <iostream>
#include <ctime>
using namespace std;
int main()
{
srand(time(0)); //use current time as seed for random generator
int random_variable = rand();
cout << "Random value on [0 " << RAND_MAX << "]: "
<< random_variable << '\n';
}
there is already question in SO check if that helps Eclipse Method could not be resolved in a simple program C++
Never use time() to initialize srand()..
EDIT:
Now it seems many people got this kind of problem. I found a question How do I fix Eclipse CDT Error “Function 'isdigit' could not be resolved. He is facing the same problem. The asker suggested a work around to this in his question edit.
Quoted from that question:
I now believe this to be a Code Analysis problem. A better solution is
to edit the Code Analysis options to make "Function could not be
resolved" be a warning instead of an error. That way you can see the
warnings in Problems view, but continue to work. If the function is
REALLY missing, the compiler will tell you! I also have a new theory,
that the problem is with the Code Analyzer following symlinks, because
all of the "missing" functions are in symlinked include files. Would
love any input on this theory.
Hope that points to solve the problem.
; should not be there after #include.
#include <iostream>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include files shoule not end with ;