I have a std::string such as 20040531, I want to format this as 2004.05.31.
Apart from the straight forward way of doing an std::insert at respective locations, is there a better way to do this using Boost?
PS. I cannot use other Boost calls to get date/time as this string is returned via a custom API. So this question is reduced to basic string formatting which may not sound exciting, but I am trying to learn Boost.
You could use boost::format...
#include <string>
#include "boost/format.hpp"
#include <iostream>
int main()
{
std::string a("20040531");
std::cout << boost::format("%1%.%2%.%3%")
% a.substr(0,4) % a.substr(4,2) % a.substr(6,2);
}
You specifically asked about doing this using Boost, but if you wanted to do this in C++ without introducing a dependency on Boost then you could just use a stream to achieve the same thing:
#include <sstream>
#include <string>
#include <iostream>
int main()
{
std::stringstream s;
std::string a("20040531");
s << a.substr(0,4) << '.' << a.substr(4,2) << '.' << a.substr(6,2);
std::cout << s.str();
}
Related
I have tried many things but they don't seem to work.
#include <iostream>
#include <locale>
using namespace std;
int main() {
setlocale(LC_ALL, "en-US.utf8");
std::string uni = u8"ユチエフー８";
std::cout << uni;
std::cin.get();
return 0;
}
Please note that I want utf-8/utf-32 to work not in just this situation but most of the situations without using things like wide characters.
My code is as follows.
#include "test.h"
#include "string"
#include "iostream"
using namespace std::string::find;
test::test(){
string str ("ffs test ffs");
string str2 ("test");
if (str.find(str2) != std::string::npos) {
std::cout << "found" << "\n";
} else {
std::cout << "not found" << "\n";
}
}
the issue I'm having is this, when trying to define a string in the C++ file qt states "unknown type name 'string'". Also on line 4 my 'import' highlights string as if it doesn't exist, despite it being an option the editor suggests to me while I'm typing it. What am I doing wrong here? Everything I find is to try and fix issues passing stuff to QStrings and nothing related to my issue as far as I can tell. I've tried both types of importing #include <thing> and #include "thing" on all the imports it doesn't seem to make a difference.
Use std::string instead of string.
#include "test.h"
#include <string>
#include <iostream>
test::test(){
std::string str ("ffs test ffs");
std::string str2 ("test");
if (str.find(str2) != std::string::npos) {
std::cout << "found" << "\n";
} else {
str::cout << "not found" << "\n";
}
}
Don't use using namespace (of course in your case, it wasn't a namespace, so that's another error), use <> for system headers.
After inclusion of the appropriate headers iostream, string etc, you can write:
using std::string;
This will bring in only string from the namespace std into your program.
And you can do this if you want to avoid typing std::string everywhere. You can do this for stream objects like cout, cin as well.
using std::cout;
using std::cin;
Use Scope operator :: in Your Code and Access manually to std class
std::string
it will help you !
Could any one help me to figure out which the following code cannot build successfully:
#include <iostream>
int main(void){
std::string str1("sfsfasfdsdf");
std::cout << str1 << std::endl;
return 1;
}
Thanks.
You have to include std::string header:
#include <string>
EDIT: According to #ShafikYaghmour's comments, include iostream sometimes brings in string, but it may not be the case for you if you only have the posted code.
I'm using boost::date_time and I got a time_t, that have been generated by a library using the time() function from the C standard library.
I'm looking for a way get a local time from that time_t. I'm reading the documentation and can't find any way to do this without providing a time zone, that I don't know about because it's dependant on the machine's locale, and I can't find any way to get one from it.
What am I missing?
boost::posix_time::from_time_t()
#include <ctime>
#include <ostream>
#include <iostream>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/date_time/local_time_adjustor.hpp>
#include <boost/date_time/c_local_time_adjustor.hpp>
boost::posix_time::ptime local_ptime_from_utc_time_t(std::time_t const t)
{
using boost::date_time::c_local_adjustor;
using boost::posix_time::from_time_t;
using boost::posix_time::ptime;
return c_local_adjustor<ptime>::utc_to_local(from_time_t(t));
}
int main()
{
using boost::posix_time::to_simple_string;
using boost::posix_time::from_time_t;
std::time_t t;
std::time(&t); // initalize t as appropriate
std::cout
<< "utc: "
<< to_simple_string(from_time_t(t))
<< "\nlocal: "
<< to_simple_string(local_ptime_from_utc_time_t(t))
<< std::endl;
}
For this task, I'd ignore boost::date_time and just use localtime (or localtime_r, if available) from the standard library.
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I tried this, but it didn't work.
#include <string>
string someString("This is a string.");
printf("%s\n", someString);
#include <iostream>
std::cout << someString << "\n";
or
printf("%s\n",someString.c_str());
You need to access the underlying buffer:
printf("%s\n", someString.c_str());
Or better use cout << someString << endl; (you need to #include <iostream> to use cout)
Additionally you might want to import the std namespace using using namespace std; or prefix both string and cout with std::.
You need #include<string> to use string AND #include<iostream> to use cin and cout. (I didn't get it when I read the answers). Here's some code which works:
#include<string>
#include<iostream>
using namespace std;
int main()
{
string name;
cin >> name;
string message("hi");
cout << name << message;
return 0;
}
You can't call "printf" with a std::string in parameter.
The "%s" is designed for C-style string : char* or char [].
In C++ you can do like that :
#include <iostream>
std::cout << YourString << std::endl;
If you absolutely want to use printf, you can use the "c_str()" method that give a char* representation of your string.
printf("%s\n",YourString.c_str())
If you'd like to use printf(), you might want to also:
#include <stdio.h>
While using string, the best possible way to print your message is:
#include <iostream>
#include <string>
using namespace std;
int main(){
string newInput;
getline(cin, newInput);
cout<<newInput;
return 0;
}
this can simply do the work instead of doing the method you adopted.